NRPP Radon Mitigation Specialist (RMS) Exam — Questions and Answers

Question 1: A mitigation system installed five years ago suddenly shows a significant drop in negative pressure. What is the most likely cause?

Radon levels naturally decreasing over time
Fan motor wear or bearing failure reducing fan performance (Correct answer)
Natural degradation of the concrete slab
Seasonal changes in outdoor temperature

Correct answer: Fan motor wear or bearing failure reducing fan performance

Fan motors and bearings degrade over time, causing reduced airflow and lower negative pressure, which is a common reason for gradual or sudden system performance decline.

Question 2: When testing a newly installed commercial SSD system, what instrument is used to verify negative pressure at each suction point?

Manometer or digital differential pressure gauge (Correct answer)
Anemometer
Geiger counter
Radon electret ion chamber

Correct answer: Manometer or digital differential pressure gauge

A manometer or digital differential pressure gauge measures the pressure differential between the sub-slab and the building interior to confirm depressurization.

Question 3: What does the term 'working level' (WL) measure in the context of radon?

The annual effective dose to building occupants
The concentration of radon progeny (decay products) in air (Correct answer)
The radon concentration in soil at the foundation
The mitigation system's sub-slab pressure differential

Correct answer: The concentration of radon progeny (decay products) in air

A working level (WL) is a unit measuring the concentration of short-lived radon progeny in air, defined as any combination releasing 1.3×10⁵ MeV of alpha energy per liter.

Question 4: When installing a sub-slab depressurization (SSD) system, what is the minimum recommended suction pit diameter?

12 inches
1 inch
6 inches
3 inches (Correct answer)

Correct answer: 3 inches

A suction pit of at least 3 inches in diameter is recommended to ensure adequate airflow communication beneath the slab.

Question 5: What is the primary purpose of performing a post-mitigation test rather than relying on system diagnostics alone?

To verify that actual indoor air radon levels have been reduced to acceptable concentrations (Correct answer)
To measure fan static pressure after installation
To document sub-slab aggregate permeability
To comply with state licensing renewal requirements

Correct answer: To verify that actual indoor air radon levels have been reduced to acceptable concentrations

System diagnostics confirm the fan and piping are functioning, but only an air quality test can verify that radon concentrations in breathing air have been reduced.

Question 6: What does a manometer reading of -5 Pa at the diagnostic hole indicate in an active SSD system?

The system is creating positive pressure under the slab
The fan has failed and needs replacement
Radon levels are at 5 pCi/L
The fan is drawing negative pressure successfully under the slab (Correct answer)

Correct answer: The fan is drawing negative pressure successfully under the slab

A negative Pa reading (below zero) confirms the SSD fan is successfully creating the intended negative pressure field beneath the slab.

Question 7: When is block wall depressurization (BWD) an appropriate radon mitigation technique?

In homes with poured concrete walls and high water tables
In all basement applications as a supplement to SSD
In homes with hollow masonry block foundation walls where radon enters through the block (Correct answer)
Only in commercial buildings with CMU construction

Correct answer: In homes with hollow masonry block foundation walls where radon enters through the block

BWD is specifically used when radon migrates through the hollow cores of concrete masonry unit (CMU) block foundation walls, creating suction inside the block cavities.

Question 8: Which condition would require an RMS to use a combination of sub-slab depressurization and block wall depressurization in a basement installation?

When the homeowner requests it for aesthetic reasons
When radon levels are below 2 pCi/L
When hollow block foundation walls are a primary radon entry pathway in addition to the slab (Correct answer)
When the fan is undersized

Correct answer: When hollow block foundation walls are a primary radon entry pathway in addition to the slab

Hollow block walls can harbor radon and must be depressurized separately when identified as a significant entry pathway alongside the slab.

Question 9: What is the minimum number of post-mitigation radon tests required before issuing a compliance certificate under most state programs?

Three consecutive short-term tests
No testing required
One short-term or long-term test (Correct answer)
Two simultaneous tests averaged

Correct answer: One short-term or long-term test

Most programs require at least one post-mitigation test to verify the system has reduced radon below the action level.

Question 10: When probing multiple diagnostic holes, what finding indicates that a second suction point is necessary?

All holes show equal negative pressure
One or more sections show no negative pressure response (Correct answer)
Radon levels drop after installing the first suction point
The fan is drawing too much current

Correct answer: One or more sections show no negative pressure response

Areas that show no pressure response are isolated from the suction point and require their own dedicated suction pit.

Question 11: An RMS is asked to provide a written proposal for a mitigation job. Which element is MOST critical to include?

The homeowner's credit score
Scope of work, cost, and post-mitigation testing plan (Correct answer)
A list of competing contractors
Neighborhood radon averages

Correct answer: Scope of work, cost, and post-mitigation testing plan

A professional proposal must clearly outline the work scope, pricing, and post-installation verification testing to set proper expectations.

Question 12: What type of radon test provides the most accurate long-term average?

Alpha track detector deployed for 91 days to 1 year (Correct answer)
A 48-hour charcoal canister test
An electronic radon detector running for 4 hours
A grab sample collected in 5 minutes

Correct answer: Alpha track detector deployed for 91 days to 1 year

Alpha track detectors deployed for 91 days to 1 year provide the most accurate long-term average radon concentration, accounting for seasonal and daily fluctuations.

Question 13: A mitigation fan is operating but post-mitigation radon tests show levels above 4 pCi/L. Which diagnostic step should be performed first?

Check for air bypasses such as open sumps, cracks, or uncapped drains (Correct answer)
Increase the fan exhaust height
Replace the fan immediately
Install additional fans in series

Correct answer: Check for air bypasses such as open sumps, cracks, or uncapped drains

Air bypasses allow soil gas to enter the living space even when the system is running, and are the most common cause of persistent elevated radon post-installation.

Question 14: What is the half-life of radon-222?

1 hour
100 years
30 seconds
3.8 days (Correct answer)

Correct answer: 3.8 days

Radon-222 has a half-life of approximately 3.8 days, meaning half of any given amount will decay into its progeny in that time period.

Question 15: When should a radon contractor perform a post-mitigation test?

Immediately after system installation, before occupants return
One year after installation during annual maintenance
Only if the occupant reports symptoms
At least 24 hours after system activation, following EPA/state protocols (Correct answer)

Correct answer: At least 24 hours after system activation, following EPA/state protocols

Post-mitigation testing should occur at least 24 hours after activation, following EPA-recommended protocols, to verify the system achieved the desired radon reduction.

Question 16: What is the purpose of a system failure warning device on a radon mitigation system?

To warn when outdoor radon levels are elevated
To indicate when the fan or system is no longer operating correctly (Correct answer)
To signal when the exhaust pipe becomes clogged
To alert occupants when radon levels exceed 4 pCi/L

Correct answer: To indicate when the fan or system is no longer operating correctly

A system failure warning device (visual or audible) alerts occupants when the mitigation system fan has stopped operating or system pressure has been lost.

Question 17: Which type of soil is most likely to be associated with high radon entry potential into a building?

Dense clay with low permeability
Coarse gravel or fractured rock with high permeability (Correct answer)
Silty loam with moderate moisture content
Organic peat with high moisture retention

Correct answer: Coarse gravel or fractured rock with high permeability

Coarse, permeable soils like gravel or fractured rock allow radon gas to migrate easily toward a building foundation, increasing entry potential.

Question 18: A smoke pencil or puffer is used during radon diagnostic testing primarily to:

Calibrate a continuous radon monitor
Test for carbon monoxide leaks in the gas line
Measure radon concentration in soil gas
Identify air pathways and verify airflow direction around the foundation (Correct answer)

Correct answer: Identify air pathways and verify airflow direction around the foundation

A smoke pencil visualizes airflow patterns to identify where soil gas may be entering and whether the system is drawing air effectively.

Question 19: What is the recommended approach when a commercial building has a combination of crawl space, basement, and slab-on-grade areas?

Use indoor air pressure equalization to serve all foundation types
Address only the highest radon area and monitor the rest
Install separate mitigation systems tailored to each foundation type (Correct answer)
Install one large fan connected to a manifold serving all areas

Correct answer: Install separate mitigation systems tailored to each foundation type

Each foundation type has different pressure dynamics and radon pathways; separate systems (SSD, SMD, BVS) designed for each area provide the most reliable mitigation.

Question 20: Which record must an RMS retain for a minimum period specified by their certifying body after completing a mitigation project?

Installation records, test results, and system diagrams (Correct answer)
Only the client invoice
Permits issued by local authorities only
Fan model numbers only

Correct answer: Installation records, test results, and system diagrams

Certification bodies require retention of full installation records including test data and system diagrams for quality assurance and dispute resolution.

Question 21: In a multi-zone SSD system, what component allows the contractor to balance airflow between suction points?

Inline HEPA filter
Adjustable gate valve or damper (Correct answer)
Pressure relief valve
Backflow preventer

Correct answer: Adjustable gate valve or damper

Adjustable gate valves or dampers allow the contractor to restrict or balance airflow at individual suction points within a multi-zone system.

Question 22: What does the term 'system failure warning device' refer to in a commercial radon mitigation system?

A visual or audible indicator that alerts occupants when the fan fails or loses pressure (Correct answer)
A CO detector wired to the fire panel
A shut-off valve that closes if radon exceeds 4 pCi/L
An HVAC interlock that stops the air handler if radon rises

Correct answer: A visual or audible indicator that alerts occupants when the fan fails or loses pressure

A system failure warning device (such as a manometer or alarm) alerts building managers when the mitigation fan loses suction or fails.

Question 23: Which diagnostic tool is used to measure the pressure differential between the basement air and the sub-slab soil to assess radon entry potential?

Radon continuous monitor
Smoke pencil
Blower door fan
Manometer or digital pressure gauge (Correct answer)

Correct answer: Manometer or digital pressure gauge

A manometer (digital or liquid) connected to a small probe hole through the slab measures the pressure difference between the sub-slab zone and the basement air, indicating the driving force for radon entry.

Question 24: What is the purpose of a diagnostic smoke test during commercial building radon mitigation planning?

To locate the radon fan exhaust point
To identify sub-slab communication pathways and air leakage routes (Correct answer)
To verify HVAC ductwork integrity
To test fire alarm system response to smoke

Correct answer: To identify sub-slab communication pathways and air leakage routes

Smoke tests help identify where sub-slab air communicates with the building interior and locate bypass pathways that can affect mitigation system performance.

Question 25: Which practice best protects an RMS when a client disputes the effectiveness of a mitigation system years after installation?

Photographs of the exterior pipe only
Verbal assurances given at the time of installation
Complete written installation records, pre/post test results, and signed client acknowledgments (Correct answer)
A general business receipt without technical details

Correct answer: Complete written installation records, pre/post test results, and signed client acknowledgments

Comprehensive written documentation — measurements, specifications, test results, and client signatures — is the professional's best defense in disputes.

Question 26: During diagnostic testing of a slab-on-grade home, a technician notices that a floor drain is open to the sub-slab area. What is the appropriate response?

Install the mitigation fan directly in the drain opening
Identify it as a potential radon bypass pathway and address it in the mitigation plan (Correct answer)
Ignore it because drains are sealed by water traps
Fill the drain with concrete permanently without further assessment

Correct answer: Identify it as a potential radon bypass pathway and address it in the mitigation plan

Open floor drains can be direct pathways for soil gas radon to enter the living space and must be addressed as part of a complete mitigation design.

Question 27: When performing a building pressure field extension test, a contractor drills a small hole and uses a device to measure air movement. What instrument is used?

Carbon monoxide detector
Digital manometer or incense stick (Correct answer)
Combustible gas sniffer
Continuous radon monitor

Correct answer: Digital manometer or incense stick

A digital manometer or incense stick/smoke puffer is used to detect air movement and measure pressure differential at the test hole.

Question 28: A mitigator places a post-mitigation test device in a storage closet in the basement. Why is this placement improper?

Closets are too small for accurate diffusion
The device must be placed in a frequently occupied area of the lowest livable level (Correct answer)
Storage areas have higher humidity that interferes with charcoal canisters
Closets often have gaps that allow outside air infiltration

Correct answer: The device must be placed in a frequently occupied area of the lowest livable level

Test devices must be placed in frequently occupied spaces because the purpose is to assess actual human exposure, not radon levels in unoccupied storage areas.

Question 29: Under AARST-ANSI standards, what is the minimum required warranty period an RMS must offer for a sub-slab depressurization system?

2 years
1 year (Correct answer)
5 years
6 months

Correct answer: 1 year

AARST-ANSI standards require a minimum one-year workmanship warranty on radon mitigation systems.

Question 30: What is the purpose of the diagnostic System Performance Check (SPC) that ANSI/AARST standards require after radon system installation?

To determine if a second fan is needed before any testing
To verify that the system is operating as designed by measuring pressure differentials and airflow (Correct answer)
To calculate the contractor's invoice for the homeowner
To satisfy EPA mandatory inspection requirements

Correct answer: To verify that the system is operating as designed by measuring pressure differentials and airflow

The SPC verifies system performance by measuring sub-slab pressure differentials and fan operation, confirming the system is functioning as designed before post-mitigation testing.

Question 31: What does a U-tube manometer permanently installed on a mitigation system allow a homeowner to monitor?

The indoor radon concentration level
Whether the fan is maintaining negative pressure in the suction pipe (Correct answer)
Fan motor operating temperature
The outdoor radon concentration

Correct answer: Whether the fan is maintaining negative pressure in the suction pipe

The U-tube manometer provides a visual indicator that the system is functioning by showing fluid displacement corresponding to negative pressure in the pipe.

Question 32: What is the purpose of a pressure field extension (PFE) test during a pre-mitigation diagnostic?

To measure radon levels in the air
To identify asbestos beneath the slab
To test the soil's moisture content
To determine how far negative pressure extends under the slab from a suction point (Correct answer)

Correct answer: To determine how far negative pressure extends under the slab from a suction point

The PFE test uses a vacuum and manometer to map how far suction can communicate under the slab, guiding pipe placement decisions.

Question 33: Which condition would most likely INCREASE radon entry in a commercial building with a sub-slab depressurization system already installed?

Suction point located near sump pit
HVAC system creating negative pressure relative to sub-slab (Correct answer)
Slab crack sealed with epoxy
Fan operating continuously

Correct answer: HVAC system creating negative pressure relative to sub-slab

If the building HVAC creates interior negative pressure greater than the SSD system's depressurization, radon can be pulled in through slab cracks and openings.

Question 34: What does 'building depressurization' mean in the context of radon entry, and how does it affect mitigation?

A measurement taken before and after fan installation
Natural conditions that make the building interior lower-pressure than the soil, increasing radon entry (Correct answer)
A deliberate step in the mitigation process that seals the building
The process of reducing indoor pressure with exhaust fans to test for leaks

Correct answer: Natural conditions that make the building interior lower-pressure than the soil, increasing radon entry

Building depressurization occurs when the interior becomes lower-pressure than surrounding soil, actively drawing radon inward; SSD systems counter this by making sub-slab pressure even lower.

Question 35: Where should the radon vent pipe exhaust be located?

Below the foundation level
Above the roofline, at least 10 feet from windows and openings (Correct answer)
At ground level on an exterior wall
Inside the garage

Correct answer: Above the roofline, at least 10 feet from windows and openings

The radon exhaust must terminate above the roof and at least 10 feet from any operable opening to prevent re-entry of radon into the building.

Question 36: A diagnostic test reveals very low sub-slab airflow despite a high-powered fan. What is the most likely cause?

The fan is oversized for the application
The sub-slab fill has very low permeability such as clay or fine sand (Correct answer)
The sub-slab gravel bed is too thick
The radon level is naturally below the action level

Correct answer: The sub-slab fill has very low permeability such as clay or fine sand

Low-permeability sub-slab materials like clay restrict air movement, resulting in poor pressure field extension regardless of fan power.

Question 37: Which type of continuing education activity typically qualifies for NRPP renewal credit?

General construction safety courses
Radon-specific technical training, conferences, or approved webinars (Correct answer)
HVAC installation training
General business accounting courses

Correct answer: Radon-specific technical training, conferences, or approved webinars

NRPP CE credits require radon-specific or directly relevant technical training, not general business or unrelated construction courses.

Question 38: Which soil characteristic most strongly promotes radon transport toward a building foundation?

Low porosity
High permeability (coarse gravel or sand) (Correct answer)
High clay content
High moisture content

Correct answer: High permeability (coarse gravel or sand)

Highly permeable soils such as coarse gravel and sand allow soil gas to move freely, greatly increasing the rate of radon transport to the building foundation.

Question 39: Which type of radon test device is considered a 'passive' measurement device?

Continuous radon monitor
Flow-through ionization chamber
Electret ion chamber (Correct answer)
Lucas cell scintillation device

Correct answer: Electret ion chamber

Electret ion chambers are passive devices that do not require power or active airflow to collect radon measurements.

Question 40: An RMS notices that a new competitor is undercutting prices by skipping diagnostic testing. What is the most constructive professional response?

Offer discounts only to clients who ask about the competitor
Educate clients on why diagnostics are essential for proper system design (Correct answer)
Report the competitor to the EPA immediately without investigation
Match the competitor's pricing by also skipping diagnostics

Correct answer: Educate clients on why diagnostics are essential for proper system design

Educating clients about the value of proper diagnostics distinguishes quality work and upholds professional standards without unfair competitive tactics.

Question 41: According to EPA guidelines, how long should a homeowner wait after installing a mitigation system before conducting a short-term post-mitigation test?

Immediately upon system startup with windows open
At least 24 hours but testing should be conducted under closed-house conditions (Correct answer)
30 days to allow the system to reach equilibrium
24 hours

Correct answer: At least 24 hours but testing should be conducted under closed-house conditions

Post-mitigation short-term tests should be conducted under closed-house conditions starting at least 24 hours after the system is installed and running.

Question 42: What ethical standards guide RMS professionals in their work?

Ethical standards are suggestions, not requirements
Ethics only apply when clients are watching
Integrity, objectivity, confidentiality, and professional competence in all engagements (Correct answer)
Maximizing personal profit is the primary ethical obligation

Correct answer: Integrity, objectivity, confidentiality, and professional competence in all engagements

Professional ethics require maintaining the highest standards of integrity, objectivity, and confidentiality while continuously developing competence.

Question 43: Which federal agency sets the occupational exposure limits for radon in mines and underground workplaces?

OSHA
MSHA (Correct answer)
EPA
CDC

Correct answer: MSHA

The Mine Safety and Health Administration (MSHA) sets and enforces radon exposure limits specifically for underground miners and mining operations.

Question 44: A building's 'air tightness' as measured by a blower door test is expressed in which unit relevant to radon assessment?

Pascals per square foot (Pa/ft²)
BTU per hour per square foot (BTU/hr/ft²)
Cubic feet per minute at 25 Pascals (CFM25)
Air changes per hour at 50 Pascals (ACH50) (Correct answer)

Correct answer: Air changes per hour at 50 Pascals (ACH50)

Blower door tightness is standardized as ACH50, the number of times the building volume is exchanged per hour when the house is depressurized to 50 Pascals, which correlates with radon dilution potential.

Question 45: During a block-wall depressurization diagnostic, what is primarily being assessed?

The structural integrity of the foundation wall
Whether hollow cores in block walls can be depressurized as a radon entry pathway (Correct answer)
Moisture levels in the masonry blocks
The R-value of the exterior wall insulation

Correct answer: Whether hollow cores in block walls can be depressurized as a radon entry pathway

Block walls with hollow cores can serve as radon entry and transport pathways; diagnostics assess whether those cores communicate and can be effectively evacuated.

Question 46: How soon after a sub-slab depressurization system is installed should post-mitigation testing begin?

At least 24 hours after installation with the system running (Correct answer)
Immediately after installation
90 days after installation
30 days after installation

Correct answer: At least 24 hours after installation with the system running

EPA guidelines recommend waiting at least 24 hours after system activation before conducting post-mitigation testing to allow radon levels to stabilize.

Question 47: What is the primary goal of health and safety regulations in radon mitigation?

To reduce the time spent on mitigation.
To increase the cost of mitigation systems.
To ensure safe and effective radon mitigation (Correct answer)
To eliminate the need for radon testing.

Correct answer: To ensure safe and effective radon mitigation

Health and safety regulations in radon mitigation are designed to protect both the occupants of the building and the mitigation specialists performing the work. These regulations ensure that mitigation systems are installed correctly, effectively reduce radon levels, and do not introduce new hazards. The overarching goal is to achieve safe indoor air quality while ensuring worker safety.

Question 48: A continuous radon monitor placed in a basement shows significantly higher readings at night than during the day. What is the most likely explanation?

Stack effect causing increased radon entry overnight (Correct answer)
Interference from outdoor radon sources
Device malfunction at lower temperatures
Battery voltage fluctuation affecting sensor accuracy

Correct answer: Stack effect causing increased radon entry overnight

The stack effect increases overnight when windows and doors are closed and temperature differentials drive soil gas (including radon) into the building.

Question 49: What physical property of radon makes it particularly dangerous indoors compared to outdoors?

It is heavier than air and cannot disperse in open spaces
It emits gamma radiation that penetrates building walls
It reacts chemically with building materials to form toxic compounds
It accumulates indoors due to limited dilution and ventilation (Correct answer)

Correct answer: It accumulates indoors due to limited dilution and ventilation

Indoors, radon accumulates because building envelopes restrict dilution by outdoor air, allowing concentrations to build up to harmful levels.

Question 50: When a radon mitigation fan is installed in the attic, what additional requirement typically applies to the electrical connection?

The fan must connect to a dedicated 20-amp circuit
A disconnect switch accessible from outside the attic is required
A GFCI outlet must be used due to potential moisture (Correct answer)
The fan wiring must use armored cable only

Correct answer: A GFCI outlet must be used due to potential moisture

Because attic environments can have moisture from condensation in the radon pipe, GFCI-protected outlets are typically required for fan installations in attic locations.

Question 51: When troubleshooting a system that has lost vacuum while the fan continues running, which component should be inspected first?

The exterior concrete slab surface
The radon test kit expiration date
The electrical panel breaker
The suction pipe for cracks, disconnections, or blockages (Correct answer)

Correct answer: The suction pipe for cracks, disconnections, or blockages

Physical disconnections, cracks, or obstructions in the suction pipe are the most common mechanical cause of vacuum loss in an otherwise running system.

Question 52: What is the most important factor when determining airflow rates in a radon mitigation system?

The cost of the system.
The size of the building.
The outdoor temperature.
The radon concentration levels in the building (Correct answer)

Correct answer: The radon concentration levels in the building

The primary goal of a radon mitigation system is to reduce radon to acceptable levels. Therefore, the initial radon concentration in the building is the most important factor in determining the required airflow rates. Higher initial radon levels may necessitate a more powerful fan or a more extensive depressurization field to achieve the desired reduction.

Question 53: What is the importance of peer review in radon mitigation?

Only management should review professional work
Peer review ensures quality, catches errors, provides learning opportunities, and maintains professional standards (Correct answer)
Peer review is unnecessary for experienced professionals
Peer review undermines professional confidence

Correct answer: Peer review ensures quality, catches errors, provides learning opportunities, and maintains professional standards

Peer review is a cornerstone of professional quality assurance, providing independent verification, knowledge sharing, and continuous improvement opportunities.

Question 54: What term describes the process by which radon-laden soil gas is pulled into a building due to indoor-outdoor pressure differences?

Diffusion
Adsorption
Emanation
Advection (Correct answer)

Correct answer: Advection

Advection is the bulk flow of soil gas driven by pressure gradients, and it is the dominant radon entry mechanism in most buildings when indoor pressure is lower than soil pressure.

Question 55: An RMS is subcontracting work to another certified mitigator. Who bears ultimate professional responsibility for the quality of the installation?

The subcontractor alone
NRPP or NRSB
The RMS who contracted with the client (Correct answer)
The client's real estate agent

Correct answer: The RMS who contracted with the client

The RMS who holds the contract with the client retains professional responsibility for ensuring the work meets applicable standards.

Question 56: What documentation best practices should RMS professionals follow?

Documentation can be completed months after the work
Maintain thorough, accurate, timely records that support findings, decisions, and compliance requirements (Correct answer)
Brief notes are always sufficient
Documentation is only needed for billing purposes

Correct answer: Maintain thorough, accurate, timely records that support findings, decisions, and compliance requirements

Comprehensive documentation provides an audit trail, supports decision-making, facilitates knowledge transfer, and demonstrates compliance with professional standards.

Question 57: Which AARST standard defines quality and qualifications for radon measurement professionals, used to benchmark RMS knowledge?

ANSI/AARST SGM-SF
ANSI/AARST MAMF
ANSI/AARST R-MMP (Correct answer)
ANSI/AARST MALB

Correct answer: ANSI/AARST R-MMP

ANSI/AARST R-MMP (Radon Measurement and Mitigation Professional) sets qualification standards for the field.

Question 58: Under ANSI/AARST SGM-SF-2017, which building component must never be used as the sole pathway for a sub-slab depressurization system?

Dirt crawl space floor
Gravel sub-base beneath the slab
Block wall interior cavities when they communicate with living space (Correct answer)
Poured concrete slab

Correct answer: Block wall interior cavities when they communicate with living space

Block wall cavities that open into living areas cannot serve as the sole depressurization pathway because pulling air through them may draw radon into living spaces rather than exhausting it.

Question 59: In a commercial building, where should the radon fan discharge point be located?

Into the HVAC return air plenum
Into the mechanical room for dilution
At least 10 feet above grade and away from windows and air intakes (Correct answer)
At grade level near the building perimeter

Correct answer: At least 10 feet above grade and away from windows and air intakes

Fan discharge must be directed away from occupied areas, windows, and air intakes—typically at least 10 feet above grade—to prevent re-entry of radon.

Question 60: What is the primary purpose of performing diagnostic testing before installing a radon mitigation system?

To verify the building's electrical capacity
To measure indoor air quality for other pollutants
To calculate the home's total square footage
To determine optimal sub-slab communication and suction point locations (Correct answer)

Correct answer: To determine optimal sub-slab communication and suction point locations

Diagnostic testing identifies where suction points should be placed by assessing sub-slab communication and soil permeability.

Question 61: Why is proper ventilation important in radon mitigation?

To reduce indoor air pollutants, including radon (Correct answer)
To enhance heating and cooling systems.
To prevent outdoor air from entering the building.
To increase the humidity levels.

Correct answer: To reduce indoor air pollutants, including radon

Proper ventilation is crucial in radon mitigation because it facilitates the exchange of indoor air with outdoor air. This process helps to dilute and remove accumulated radon gas, along with other indoor air pollutants. By bringing in fresh air and expelling contaminated air, ventilation effectively lowers the concentration of radon within the building.

Question 62: What minimum vertical height above the roofline must a radon mitigation exhaust pipe terminate according to EPA guidelines?

36 inches
12 inches (Correct answer)
24 inches
6 inches

Correct answer: 12 inches

EPA guidelines specify the exhaust pipe must terminate at least 12 inches above the roofline to ensure adequate dispersion of radon.

Question 63: Radon gas enters the human body primarily through which mechanism?

Direct gamma radiation from soil
Ingestion of contaminated water
Skin absorption
Inhalation of air containing radon and its progeny (Correct answer)

Correct answer: Inhalation of air containing radon and its progeny

Radon and its short-lived alpha-emitting progeny are inhaled and deposit energy directly onto bronchial epithelial cells.

Question 64: What is the purpose of a short-circuit test in sub-slab depressurization diagnostics?

To test the electrical wiring of the mitigation fan
To test the battery backup of the system alarm
To measure how fast radon decays in soil
To identify locations where outdoor air is entering the sub-slab and reducing system efficiency (Correct answer)

Correct answer: To identify locations where outdoor air is entering the sub-slab and reducing system efficiency

A short-circuit test identifies locations where atmospheric air enters the sub-slab zone, reducing the system's ability to maintain sufficient negative pressure.

Question 65: What is the importance of professional networking in radon mitigation?

Networking only benefits entry-level professionals
Building relationships with peers enables knowledge sharing, professional development, and career advancement (Correct answer)
Networking is a waste of time for established professionals
Only online networking has value

Correct answer: Building relationships with peers enables knowledge sharing, professional development, and career advancement

Professional networks provide opportunities for knowledge exchange, mentorship, collaboration, and staying informed about industry trends and opportunities.

Question 66: What is the primary pathway through which radon enters most U.S. residential buildings?

Through the electrical wiring system
Through cracks and openings in the foundation and slab (Correct answer)
Through the roof and attic
Through exterior walls above grade

Correct answer: Through cracks and openings in the foundation and slab

Radon, a soil gas, enters buildings primarily through cracks in foundation walls, floor-wall joints, sump pits, and other openings in the lowest structural level in contact with soil.

Question 67: If a mitigation system test pipe shows no pressure differential when the fan is running, what should be checked first?

The exterior paint on the exhaust pipe
The date of the original radon test
The indoor humidity level
Whether the suction pit properly connects to the sub-slab environment (Correct answer)

Correct answer: Whether the suction pit properly connects to the sub-slab environment

No pressure differential typically means the suction pipe is not properly connected to the sub-slab space, or the suction pit opening is blocked or sealed.

Question 68: Which condition might cause a post-mitigation test to show artificially LOW radon levels that do not reflect true long-term exposure?

The mitigation fan running at a higher-than-normal flow rate
Unusually warm outdoor temperatures reducing the stack effect (Correct answer)
Heavy rainfall saturating soil and driving radon indoors
High barometric pressure during test period

Correct answer: Unusually warm outdoor temperatures reducing the stack effect

Warm outdoor temperatures reduce the indoor-outdoor temperature differential, weakening the stack effect and decreasing radon entry, which can produce atypically low short-term test results.

Question 69: When routing the radon mitigation pipe through conditioned living space, what is required?

The pipe must be insulated with foam wrap
The pipe diameter must be reduced to 2 inches
The pipe must be painted to match interior walls
All pipe joints must be gas-tight and the pipe must be clearly labeled (Correct answer)

Correct answer: All pipe joints must be gas-tight and the pipe must be clearly labeled

Pipes routed through living space must have gas-tight joints and be labeled 'Radon Reduction System' to prevent accidental disconnection.

Question 70: When an RMS discovers an active sump pump pit during a pre-mitigation inspection, what is the primary compliance concern?

Sump pits are outside the scope of radon mitigation
The pit can be a major radon entry pathway requiring sealing or special treatment (Correct answer)
The pit will void the homeowner's warranty
The sump pump may interfere with electrical wiring

Correct answer: The pit can be a major radon entry pathway requiring sealing or special treatment

Sump pits communicate directly with the sub-slab environment and must be addressed to prevent them from bypassing the mitigation system.

Question 71: If diagnostic testing reveals that two sections of a basement have isolated sub-slab conditions with no interconnection, what mitigation design is most appropriate?

Recommend a natural ventilation approach as an alternative
Seal the entire basement floor with an epoxy coating
Design separate suction points or systems for each isolated section (Correct answer)
Install one oversized fan to handle both sections simultaneously

Correct answer: Design separate suction points or systems for each isolated section

Isolated sub-slab sections each need their own suction point to ensure adequate depressurization is achieved throughout the entire foundation.

Question 72: After post-mitigation testing confirms success, where should the test report and baseline results be kept?

Retained by both the homeowner and the mitigation contractor for future reference (Correct answer)
Discarded after the mitigation warranty period expires
Stored exclusively at the testing laboratory
Filed only with the state radon office

Correct answer: Retained by both the homeowner and the mitigation contractor for future reference

Both the homeowner and contractor should retain copies of test reports to support future home sales, warranty claims, and system performance comparisons.

Question 73: What qualifications are needed for advanced radon mitigation practice?

No additional qualifications beyond initial certification
Advanced practice requires no formal credentials
Advanced certifications, specialized training, demonstrated experience, and ongoing professional development (Correct answer)
Only a college degree in any subject

Correct answer: Advanced certifications, specialized training, demonstrated experience, and ongoing professional development

Advanced practice requires building upon foundational knowledge through specialized certifications, targeted training, and demonstrated competence in specific areas.

Question 74: Why does soil gas entry typically exceed outdoor air infiltration as a radon source, even though both enter through similar openings?

Outdoor radon decays before reaching the foundation
Outdoor air contains no radon at all
Soil gas has radon concentrations hundreds to thousands of times higher than outdoor air (Correct answer)
Soil gas enters under positive pressure while outdoor air enters under negative pressure

Correct answer: Soil gas has radon concentrations hundreds to thousands of times higher than outdoor air

Soil gas radon concentrations commonly range from 10,000 to 100,000 pCi/L, while outdoor air averages about 0.4 pCi/L, so even small volumes of soil gas entry significantly elevate indoor levels.

Question 75: A state radon program audit reveals an RMS installed a system without obtaining the required building permit. What is the most likely consequence?

A written warning with no further action
Potential license suspension and requirement to obtain retroactive permits (Correct answer)
No consequence if the system is functioning correctly
Automatic NRPP decertification

Correct answer: Potential license suspension and requirement to obtain retroactive permits

Operating without required permits can lead to license suspension, fines, and remediation requirements under state contractor law.

Question 76: ANSI/AARST standards require that an RMS contractor performing work in an occupied home provide occupants with what document before work begins?

A waiver releasing the contractor from all liability
A copy of the contractor's tax ID
A copy of the state radon map
A pre-work disclosure explaining the scope, materials, and any disturbances (Correct answer)

Correct answer: A pre-work disclosure explaining the scope, materials, and any disturbances

Pre-work disclosures ensure occupants are informed of what to expect, including dust, noise, or temporary disruptions.

Question 77: A contractor is installing an SSD system in a home with a sump pump pit. What should be done with the sump pit?

Install the suction point as far as possible from the sump pit
Remove the sump pump and fill the pit with gravel
Seal the sump pit cover gas-tight and use it as a suction point or install a separate suction pit (Correct answer)
Use the sump pit as the suction point without modification

Correct answer: Seal the sump pit cover gas-tight and use it as a suction point or install a separate suction pit

A sump pit can serve as a suction point if sealed with a gas-tight cover, since it already provides access to the sub-slab area.

Question 78: When must an RMS disclose to a client that they have a financial interest in a specific radon test device brand they are recommending?

Only in commercial projects
Always, as a conflict of interest disclosure is required before the recommendation (Correct answer)
Only when the client specifically asks
Disclosure is not required if the device is EPA-listed

Correct answer: Always, as a conflict of interest disclosure is required before the recommendation

Ethical standards and most certification codes require disclosure of financial conflicts of interest before making recommendations that could benefit the contractor.

Question 79: What is the standard pipe size for most residential sub-slab depressurization systems?

4-inch PVC
3-inch PVC (Correct answer)
1.5-inch PVC
2-inch PVC

Correct answer: 3-inch PVC

3-inch PVC Schedule 40 is the standard pipe size for most residential SSD systems, providing adequate airflow with minimal resistance.

Question 80: How does continuing education benefit RMS professionals?

Only beginners benefit from additional training
Continuing education is purely optional with no benefits
Continuing education is not needed after certification
It ensures practitioners stay current with evolving standards, technologies, and best practices (Correct answer)

Correct answer: It ensures practitioners stay current with evolving standards, technologies, and best practices

Professional fields evolve constantly — continuing education ensures practitioners maintain competence and stay current with industry developments.

Question 81: Floor-wall joints in poured concrete basements are common radon entry points because they:

Are made of a more porous concrete mix
Contain no reinforcing steel to block gas flow
Often have shrinkage gaps where the floor slab meets the foundation wall (Correct answer)
Are exposed directly to outdoor soil pressure

Correct answer: Often have shrinkage gaps where the floor slab meets the foundation wall

As concrete cures and settles, a small gap commonly forms at the joint between the floor slab and the foundation wall, providing a continuous pathway for soil gas entry.

Question 82: Radon entry through building materials (e.g., concrete, granite countertops) is classified as which type of entry mechanism?

Diffusion from the material itself (Correct answer)
Convective transport
Advection from outdoor air
Pressure-driven infiltration

Correct answer: Diffusion from the material itself

When radon emanates from radioactive decay within building materials and migrates through pore spaces into indoor air, the mechanism is diffusion driven by concentration gradients.

Question 83: Which metric recorded during post-mitigation diagnostics most directly indicates adequate sub-slab depressurization?

CO2 levels in the crawl space
Negative pressure differential between sub-slab and indoor air (inches of water column) (Correct answer)
Radon decay product concentration in basement air
Fan RPM reading from the motor label

Correct answer: Negative pressure differential between sub-slab and indoor air (inches of water column)

A negative pressure differential (measured in inches of water column) between the sub-slab and the living space confirms the system is actively pulling soil gas away from the building.

Question 84: How can natural ventilation systems contribute to radon mitigation?

It improves indoor air quality by allowing air exchange (Correct answer)
It creates an air-tight building environment.
It reduces the building's heating efficiency.
It increases indoor humidity levels.

Correct answer: It improves indoor air quality by allowing air exchange

Natural ventilation systems, such as opening windows and doors, allow for passive air exchange between the indoor and outdoor environments. This exchange helps dilute indoor radon concentrations by bringing in fresh air and expelling radon-laden air. While less controlled than active systems, it can contribute to overall indoor air quality improvement and radon reduction, especially in conjunction with other methods.

Question 85: Which type of test device is considered the gold standard for post-mitigation confirmation testing?

Electret ion chamber (E-PERM)
Long-term alpha track detector (ATD) (Correct answer)
Continuous radon monitor (CRM)
Short-term charcoal canister

Correct answer: Long-term alpha track detector (ATD)

Long-term alpha track detectors provide a 90-day or longer average, which is the most reliable measure of actual radon exposure after mitigation.

Question 86: Radon-220, also known as thoron, originates from the decay of which isotope?

Radium-226
Plutonium-239
Uranium-235
Thorium-232 through Radium-224 (Correct answer)

Correct answer: Thorium-232 through Radium-224

Thoron (Rn-220) is produced via the thorium-232 decay chain: Th-232 → … → Ra-224 → Rn-220.

Question 87: During post-mitigation testing, a continuous radon monitor (CRM) is used. What advantage does a CRM offer over a passive device?

CRMs can be mailed to a laboratory for more accurate analysis
CRMs are less expensive and easier to deploy
CRMs do not require closed-house conditions
CRMs provide hourly data allowing detection of system anomalies during the test period (Correct answer)

Correct answer: CRMs provide hourly data allowing detection of system anomalies during the test period

Continuous monitors record radon levels at regular intervals, making it possible to identify periods of elevated levels that may indicate system problems or protocol violations.

Question 88: A technician finds the system manometer shows good negative pressure, but actual airflow through the fan appears low. Which diagnostic tool would best measure actual airflow?

A smoke detector held near the exhaust
An anemometer or flow meter placed in the exhaust pipe (Correct answer)
A digital multimeter measuring fan voltage
A radon charcoal canister test kit

Correct answer: An anemometer or flow meter placed in the exhaust pipe

An anemometer measures actual air velocity in the exhaust pipe, which combined with pipe cross-sectional area yields the volumetric airflow through the system.

Question 89: How does creating a sealed environment contribute to radon mitigation?

It creates an airtight environment that prevents radon from entering (Correct answer)
It prevents natural airflow in the building.
It has no impact on radon mitigation.
It decreases the efficiency of the ventilation system.

Correct answer: It creates an airtight environment that prevents radon from entering

Creating a sealed environment, particularly in the foundation, is a fundamental component of radon mitigation. By sealing cracks, openings, and penetrations in the slab and walls, pathways for radon gas to enter the building from the soil are blocked. This reduces the amount of radon that can infiltrate, making other mitigation efforts more effective.

Question 90: In a block wall foundation, radon mitigation is complicated because:

Block walls absorb radon and release it slowly
Block walls cannot support SSD system pipes
Radon cannot enter through block walls at all
The hollow cores create multiple pathways for radon to travel (Correct answer)

Correct answer: The hollow cores create multiple pathways for radon to travel

Hollow concrete block cores create interconnected channels throughout the wall that allow radon to migrate and make pressure field extension more complex.

Question 91: Why do radon concentrations in a home typically fluctuate significantly from hour to hour and day to day?

Radon half-life varies with temperature
Wind speed, indoor HVAC operation, and occupant behavior continuously change the driving pressures and ventilation rates (Correct answer)
The rate of radium decay in soil changes throughout the day
Soil moisture is the only variable affecting radon, and it changes slowly

Correct answer: Wind speed, indoor HVAC operation, and occupant behavior continuously change the driving pressures and ventilation rates

Dynamic factors including wind pressure on the building envelope, HVAC cycling, opening of doors and windows, and stack effect changes all continuously alter the pressure differentials and air exchange rates that control radon entry and dilution.

Question 92: A post-mitigation test is conducted in a home with a basement and an attached garage. Where should the test device NOT be placed?

In the basement laundry area used daily
In the attached garage (Correct answer)
In the basement bedroom used nightly
In the basement family room near the TV

Correct answer: In the attached garage

Garages are not considered livable space and often have separate ventilation; placing a device there would not reflect occupant exposure and would likely yield an invalid low result.

Question 93: Hollow concrete block foundation walls are especially problematic for radon because they:

Contain radium deposits that emit radon directly
Block sub-slab depressurization systems from working
Absorb moisture, increasing radon emanation
Create internal voids that act as conduits for soil gas flow (Correct answer)

Correct answer: Create internal voids that act as conduits for soil gas flow

The hollow cores of concrete block walls provide interconnected channels through which soil gas can travel laterally along the wall and enter at any opening, including mortar cracks.

Question 94: How do RMS professionals contribute to organizational success?

They only perform routine tasks with no strategic impact
By applying specialized knowledge to solve problems, reduce risks, improve processes, and drive strategic outcomes (Correct answer)
Professional expertise has minimal organizational value
Only executives contribute to organizational success

Correct answer: By applying specialized knowledge to solve problems, reduce risks, improve processes, and drive strategic outcomes

Certified professionals bring specialized expertise that directly contributes to organizational goals through problem-solving, risk reduction, process improvement, and strategic decision support.

Question 95: A mitigation contractor installs an SSD system but the post-mitigation test shows only marginal reduction (e.g., from 12 pCi/L to 6 pCi/L). What is the FIRST troubleshooting step?

Add indoor air purifiers with HEPA filters to reduce radon decay products
Check system performance indicators and verify the fan is operating and creating adequate negative pressure (Correct answer)
Replace the fan with a higher-capacity unit immediately
Recommend long-term testing and wait six months before any changes

Correct answer: Check system performance indicators and verify the fan is operating and creating adequate negative pressure

Verifying that the fan is operating and the system performance indicator shows proper negative pressure is the first diagnostic step before any hardware changes.

Question 96: When performing a diagnostic communication test (pressure field extension test) under a slab, an RMS professional is evaluating:

The thickness of the concrete slab
The radon concentration at various depths
The moisture content of the soil
Whether a single suction point can depressurize the entire sub-slab area (Correct answer)

Correct answer: Whether a single suction point can depressurize the entire sub-slab area

A communication test determines if negative pressure can extend from the suction point throughout the sub-slab aggregate.

Question 97: What is the recommended minimum distance between a radon exhaust pipe termination and a window, door, or other opening into the building?

12 inches
24 inches (Correct answer)
10 feet
6 inches

Correct answer: 24 inches

EPA and most state guidelines require the exhaust termination to be at least 10 feet from any window, door, or opening to prevent re-entry of exhausted radon.

Question 98: Which statement about radon in well water is accurate?

Radon in groundwater always exceeds safe limits
Radon does not dissolve in water and is not a concern for private wells
Radon in water poses the same risk as airborne radon at the same concentration
Radon can be released from water during use (showering, dishwashing) and contribute to indoor air radon (Correct answer)

Correct answer: Radon can be released from water during use (showering, dishwashing) and contribute to indoor air radon

When radon-bearing water is agitated during household use, radon off-gasses into indoor air, typically contributing about 1/10,000 of the water concentration to indoor air levels.

Question 99: Which AARST standard section addresses the requirement for sealing all visible cracks and openings as part of a radon mitigation installation?

Fan selection criteria
Sealing and covering requirements (Correct answer)
Diagnostic testing protocol
System performance verification

Correct answer: Sealing and covering requirements

AARST standards include a sealing section requiring contractors to seal visible entry points to enhance system effectiveness.

Question 100: A radon test is invalidated if the certified radon professional suspects tampering. Which CRM data pattern most clearly indicates test interference?

Concentrations that vary between 2 pCi/L and 6 pCi/L
Readings that are consistently higher than the area average
Radon values that gradually increase overnight
An unexplained gap in hourly data during the test period (Correct answer)

Correct answer: An unexplained gap in hourly data during the test period

A gap in the continuous hourly data record indicates the device may have been moved, powered off, or otherwise tampered with, invalidating the test.

Question 101: A real estate transaction requires disclosure of a previous radon test. The test result was 3.8 pCi/L. Which statement best describes the seller's disclosure obligation?

No disclosure needed since the level is below 4 pCi/L
Federal law mandates disclosure only if mitigation was performed
Only results above 10 pCi/L require disclosure
Disclosure requirements depend on state law; many states require disclosing all known test results regardless of level (Correct answer)

Correct answer: Disclosure requirements depend on state law; many states require disclosing all known test results regardless of level

Real estate radon disclosure laws vary by state; many require sellers to disclose all known radon test results to buyers, regardless of whether the level exceeds the EPA action guideline.

Question 102: Which organization provides national proficiency program (NPP) certification for radon measurement professionals in the United States?

EPA Office of Radiation Programs
AARST-NRPP and NRSB (Correct answer)
OSHA Safety Standards Division
National Institute of Standards and Technology (NIST)

Correct answer: AARST-NRPP and NRSB

AARST-NRPP (National Radon Proficiency Program) and NRSB (National Radon Safety Board) are the two EPA-recognized certification bodies for radon measurement professionals.

Question 103: When marketing mitigation services, which practice is considered unethical under professional standards?

Listing professional certifications and credentials
Describing the types of systems installed
Advertising post-mitigation test guarantees with specific numeric targets (Correct answer)
Publishing client testimonials with permission

Correct answer: Advertising post-mitigation test guarantees with specific numeric targets

Guaranteeing specific post-mitigation radon levels is unethical because results vary with building conditions beyond the contractor's control.

Question 104: Under OSHA regulations, what personal protective equipment is required for workers core drilling through a concrete slab with potential silica exposure?

Hearing protection only
Chemical-resistant gloves and apron
N95 respirator at minimum; P100 or supplied-air respirator depending on silica levels (Correct answer)
Safety glasses only

Correct answer: N95 respirator at minimum; P100 or supplied-air respirator depending on silica levels

OSHA's silica standard (29 CFR 1926.1153) requires respiratory protection when cutting or drilling concrete, with P100 or supplied-air respirators for higher exposure tasks.

Question 105: Which condition most severely limits the effectiveness of a single-suction-point SSD system?

Low sub-slab permeability with isolated aggregate pockets (Correct answer)
High indoor radon concentrations above 10 pCi/L
Building height greater than two stories
Exterior temperatures below freezing

Correct answer: Low sub-slab permeability with isolated aggregate pockets

When sub-slab material has low permeability or is divided into isolated pockets, a single suction point cannot extend its pressure field throughout the entire area.

Question 106: Which safety measure should be taken when sealing radon entry points in a building?

Seal all cracks with paint only.
Work without any protective gear.
Ensure proper ventilation and use non-toxic sealants (Correct answer)
Use toxic sealants for better adhesion.

Correct answer: Ensure proper ventilation and use non-toxic sealants

When sealing radon entry points, it's important to use materials that are effective and safe. Non-toxic sealants prevent the introduction of harmful chemicals into the indoor environment. Proper ventilation during application helps dissipate any fumes and ensures a safe working atmosphere, protecting both the installer and future occupants.

Question 107: Which federal agency provides the primary regulatory framework and guidance documents that AARST standards are designed to complement?

EPA (Correct answer)
FEMA
CDC
OSHA

Correct answer: EPA

The U.S. Environmental Protection Agency (EPA) sets radon action levels and guidance that AARST standards are aligned with.

Question 108: During troubleshooting, a technician measures higher-than-expected negative pressure but still finds elevated radon levels. What is the most plausible explanation?

There is a radon source not addressed by the system such as radon in well water or an isolated sub-slab section (Correct answer)
The manometer is malfunctioning
Outdoor radon levels are unusually high
The fan is not powerful enough

Correct answer: There is a radon source not addressed by the system such as radon in well water or an isolated sub-slab section

When system vacuum is confirmed but radon persists, an unconnected radon source such as radon-bearing well water or an isolated sub-slab zone is a key suspect.

Question 109: What is a common mistake during radon testing that could result in inaccurate readings?

Placing devices on high shelves.
Placing devices in a well-ventilated area.
Placing devices in the center of a room.
Placing devices near windows, vents, or drafty areas (Correct answer)

Correct answer: Placing devices near windows, vents, or drafty areas

Placing radon testing devices near windows, vents, or drafty areas can lead to inaccurate readings because these locations can dilute radon concentrations. Such conditions do not represent the typical indoor air quality and can result in artificially low measurements. For accurate results, devices should be placed in undisturbed, representative areas of the lowest lived-in level.

Question 110: When should a contractor perform follow-up diagnostic verification after initial system installation?

After two years of system operation
Only when the fan fails or makes noise
Only if the homeowner specifically requests it
As part of post-installation verification before final sign-off on the job (Correct answer)

Correct answer: As part of post-installation verification before final sign-off on the job

Post-installation diagnostic checks confirm proper pressure field extension and system function before the technician certifies the job as complete.

Question 111: A contractor is bidding a commercial SSD project in a multi-tenant office building. Who must be notified before core drilling begins?

Building owner, tenants in affected areas, and local building authority if a permit is required (Correct answer)
Only the building owner
State radon program coordinator only
EPA regional office

Correct answer: Building owner, tenants in affected areas, and local building authority if a permit is required

Core drilling in occupied commercial buildings requires notifying the owner, affected tenants to minimize disruption, and the local authority having jurisdiction if a permit is required.

Question 112: According to ANSI/AARST MAH-2017, what is the minimum horizontal distance a radon fan exhaust must be from an operable window or door on the same or adjacent building?

12 inches
6 inches
10 feet (Correct answer)
20 feet

Correct answer: 10 feet

ANSI/AARST MAH-2017 requires radon exhaust discharge points to be at least 10 feet horizontally from any operable window, door, or gravity air intake to prevent re-entry.

Question 113: Which epidemiological studies provided the primary evidence linking radon to lung cancer and established risk coefficients used by EPA?

Underground miner cohort studies (uranium and hard-rock miners) (Correct answer)
Studies of residential radon in European homes
Animal inhalation studies with laboratory rats
Hospital patient retrospective studies

Correct answer: Underground miner cohort studies (uranium and hard-rock miners)

Risk coefficients for radon-induced lung cancer are primarily derived from decades-long cohort studies of underground miners with high radon exposures.

Question 114: When evaluating a sub-slab depressurization system for adequate coverage, what measurement is taken at multiple locations across the slab?

The temperature of soil gas beneath the slab
The pressure differential between the sub-slab and the building interior (Correct answer)
The moisture content of the sub-slab gravel
The slab thickness at each test point

Correct answer: The pressure differential between the sub-slab and the building interior

Pressure differential measurements at multiple points confirm that the negative pressure zone extends across the entire sub-slab area requiring coverage.

Question 115: An RMS discovers during a post-mitigation test that radon levels remain above 4 pCi/L. What is the most appropriate professional response?

Issue the client a passing report since the system is installed
Contact the state radon office only
Advise the client that further reduction is impossible
Reassess the system design and recommend corrective action (Correct answer)

Correct answer: Reassess the system design and recommend corrective action

If post-mitigation levels exceed the EPA action level, the specialist must evaluate system performance and implement corrective measures.

Question 116: What is the primary purpose of post-mitigation testing performed after a radon mitigation system installation?

To confirm indoor radon levels have been reduced to or below the EPA action level of 4 pCi/L (Correct answer)
To check pipe joint integrity with a smoke test
To satisfy insurance requirements for the contractor
To verify the fan is operating at its rated CFM

Correct answer: To confirm indoor radon levels have been reduced to or below the EPA action level of 4 pCi/L

Post-mitigation testing verifies that the system has successfully reduced radon levels to or below the EPA's action level of 4 pCi/L.

Question 117: A homeowner asks a radon contractor if their neighbor's high radon levels legally obligate them to test. What is the correct response?

No, but the contractor must report the neighbor's result to the EPA
No, radon levels vary significantly between adjacent properties and no law mandates testing based on neighbors' results (Correct answer)
Yes, state law always requires testing within 50 feet of a confirmed high-radon property
Yes, federal law requires testing when a neighbor's levels exceed 4 pCi/L

Correct answer: No, radon levels vary significantly between adjacent properties and no law mandates testing based on neighbors' results

Radon concentrations can vary dramatically between adjacent homes due to soil conditions and building characteristics; no federal or common state law mandates testing based on a neighbor's results.

Question 118: Which foundation type is BEST suited for sub-slab depressurization without major modifications?

Slab-on-grade with gravel or permeable fill beneath (Correct answer)
Basement with poured concrete walls and no sub-slab material
Crawl space with exposed soil
Pier-and-beam construction

Correct answer: Slab-on-grade with gravel or permeable fill beneath

Slab-on-grade with permeable sub-slab material (gravel) allows easy air movement, making SSD highly effective with minimal modification.

Question 119: Which radon test placement rule applies during post-mitigation testing in a home with a finished basement?

Test in the bedroom with the highest occupancy
Test in the lowest livable area of the home (Correct answer)
Test only on the first floor above grade
Test at the geometric center of the house

Correct answer: Test in the lowest livable area of the home

Post-mitigation testing should be conducted in the lowest livable level to capture worst-case radon concentrations where occupants spend time.

Question 120: What is the purpose of a U-tube manometer in a radon mitigation system?

To balance air pressure across zones
To indicate fan operating pressure differential (Correct answer)
To monitor crawl space humidity
To measure radon gas concentration

Correct answer: To indicate fan operating pressure differential

A U-tube manometer installed in the pipe indicates the pressure differential, confirming the fan is operating and creating suction.

Question 121: In a commercial building with a hollow block foundation wall, what mitigation technique targets radon accumulating inside the block cavities?

Sub-slab depressurization through core holes in the slab
Positive pressurization of the building interior
Sealing the exterior of the block wall with waterproof membrane
Block wall depressurization using suction applied to the block cores (Correct answer)

Correct answer: Block wall depressurization using suction applied to the block cores

Block wall depressurization applies suction directly to hollow block cores to intercept radon before it enters the occupied space.

Question 122: A client asks an RMS to certify a mitigation system installed by an uncertified contractor. What should the RMS do?

Sign the documentation if the system appears functional
Charge a fee and provide the certification
Consult with the contractor first before deciding
Refuse and explain ethical and legal obligations (Correct answer)

Correct answer: Refuse and explain ethical and legal obligations

Certifying work not performed under the RMS's supervision violates professional ethics and potentially state regulations.

Question 123: A school building has radon levels of 6.2 pCi/L in occupied classrooms. According to EPA guidance, what action is recommended?

Increase ventilation only and retest in one year
Re-test in 90 days before deciding
Mitigate the building as soon as possible (Correct answer)
Post radon warnings and continue monitoring

Correct answer: Mitigate the building as soon as possible

EPA recommends mitigation when school radon levels exceed 4 pCi/L in frequently occupied areas.

Question 124: When radon decays inside the lung, its progeny deposit alpha energy predominantly in which cell layer?

Pleural mesothelial cells
Alveolar type II pneumocytes
Basal cells and secretory cells of the bronchial epithelium (Correct answer)
Pulmonary capillary endothelium

Correct answer: Basal cells and secretory cells of the bronchial epithelium

Basal and secretory cells in the bronchial epithelium are the at-risk target cells because they are close to the airway surface where progeny deposit.

Question 125: Which scenario would most likely trigger a mandatory re-inspection under NRPP quality assurance protocols?

A homeowner painting over the system label
A post-mitigation test result above 4 pCi/L after system optimization (Correct answer)
A test conducted during unusually cold weather
A fan replaced with an identical model under warranty

Correct answer: A post-mitigation test result above 4 pCi/L after system optimization

A post-mitigation level above the EPA action level after optimization attempts indicates the system is not achieving compliance and requires re-evaluation.

Question 126: In building science, 'air barrier continuity' is important for radon control because gaps in the air barrier:

Increase radium deposits near the foundation
Increase the rate of radon decay to progeny
Reduce the effectiveness of radon test kits
Allow pressure-driven soil gas to bypass intended entry resistance points (Correct answer)

Correct answer: Allow pressure-driven soil gas to bypass intended entry resistance points

A discontinuous air barrier creates unintended pathways where pressure-driven soil gas can move freely into conditioned spaces, undermining both passive and active radon mitigation strategies.

Question 127: What is the purpose of sealing slab penetrations and expansion joints in a commercial mitigation project?

To comply with ADA accessibility standards
To reduce radon entry pathways and improve system efficiency (Correct answer)
To meet structural engineering requirements
To increase sub-slab pressure uniformity

Correct answer: To reduce radon entry pathways and improve system efficiency

Sealing penetrations and joints reduces bypass pathways that allow radon-laden soil gas to enter the building, improving overall mitigation effectiveness.

Question 128: What unit of measurement is used for radon concentration in the United States?

Becquerels per cubic meter (Bq/m³) only
Milligrams per liter (mg/L)
Picocuries per liter (pCi/L) (Correct answer)
Parts per million (ppm)

Correct answer: Picocuries per liter (pCi/L)

The United States uses picocuries per liter (pCi/L) as the standard unit for measuring radon concentration in air, while most other countries use becquerels per cubic meter.

Question 129: How should RMS professionals handle conflicts of interest?

Only financial conflicts matter
Disclose potential conflicts, recuse when appropriate, and always prioritize the client's best interests (Correct answer)
Conflicts of interest are normal and need not be addressed
Keep conflicts hidden to avoid complications

Correct answer: Disclose potential conflicts, recuse when appropriate, and always prioritize the client's best interests

Conflicts of interest must be identified, disclosed, and managed transparently to maintain professional integrity and client trust.

Question 130: A radon contractor is asked to provide a written estimate for a mitigation system. According to professional ethics and ANSI/AARST standards, the estimate should include:

Scope of work, system components to be installed, warranty terms, and post-mitigation testing provisions (Correct answer)
A federally standardized price based on EPA fee schedules
Only labor costs; materials are billed separately after installation
Only the final price with no itemization required

Correct answer: Scope of work, system components to be installed, warranty terms, and post-mitigation testing provisions

Professional standards and consumer protection principles require that written estimates include scope of work, materials, warranties, and provisions for post-mitigation testing so clients understand what is being provided.

Question 131: Under the Clean Air Act, radon is regulated as an indoor air pollutant primarily through which mechanism?

National Ambient Air Quality Standards (NAAQS)
Title IV acid rain program provisions
Voluntary guidance programs and state-level regulations rather than federal NAAQS (Correct answer)
Hazardous Air Pollutant (HAP) emission limits for buildings

Correct answer: Voluntary guidance programs and state-level regulations rather than federal NAAQS

Unlike outdoor pollutants, indoor radon is addressed through EPA voluntary guidance, public education, and state regulatory programs rather than binding federal NAAQS under the Clean Air Act.

Question 132: What does a failing post-mitigation test indicate?

The building is permanently unsafe
The system may need additional suction points or sealing (Correct answer)
Radon mitigation is impossible for this building
The test device was defective

Correct answer: The system may need additional suction points or sealing

A post-mitigation test showing radon at or above 4 pCi/L indicates the system needs optimization: additional suction points, better sealing, or a more powerful fan.

Question 133: An RMS is working in a state with no radon-specific licensing law. Which standards should still govern their work?

EPA model standards and ASTM E2121 along with their national certification body requirements (Correct answer)
No standards apply without state law
Only local building codes
The contractor's own internal procedures

Correct answer: EPA model standards and ASTM E2121 along with their national certification body requirements

In states without specific radon laws, EPA model standards and ASTM E2121 plus certification body requirements still apply as the professional standard of care.

Question 134: According to EPA and AARST guidelines, which type of foundation requires the most complex diagnostic assessment before selecting a mitigation approach?

Crawlspace with plastic sheeting
Block wall foundation (Correct answer)
Poured concrete slab
Basement with exposed soil floor

Correct answer: Block wall foundation

Block wall (hollow block) foundations have interconnected cavities that complicate pressure field extension and require careful diagnostics.

Question 135: A post-mitigation test result of 1.8 pCi/L is obtained in December. The homeowner asks if they should retest in summer. What is the best advice?

Summer retesting is appropriate since seasonal lows in winter can mask higher annual averages (Correct answer)
No retest is needed since the result is below 4 pCi/L
Retest only if the mitigation fan fails
Summer results are always lower so retesting would be unnecessary

Correct answer: Summer retesting is appropriate since seasonal lows in winter can mask higher annual averages

Radon levels can vary significantly by season; winter tests in cold climates often reflect elevated stack effect and may not represent typical annual exposure, making a follow-up test useful.

Question 136: Under EPA guidelines, what is the maximum acceptable radon level in a home before mitigation is strongly recommended?

8 pCi/L
4 pCi/L (Correct answer)
10 pCi/L
2 pCi/L

Correct answer: 4 pCi/L

The EPA recommends mitigation when radon levels are at or above 4 pCi/L.

Question 137: During a pressure field extension test, a manometer is inserted into a diagnostic hole. What result indicates good sub-slab communication?

No pressure change at the diagnostic hole
A negative pressure reading similar to that at the suction pit (Correct answer)
A positive pressure reading at the diagnostic hole
A reading of exactly zero pascals

Correct answer: A negative pressure reading similar to that at the suction pit

A negative pressure reading at the diagnostic hole similar to the suction pit pressure confirms the sub-slab is well-interconnected.

Question 138: A pressure differential of -5 Pascals between a basement and the soil beneath it would be expected to:

Push indoor air into the soil, preventing radon entry
Increase radon entry by driving soil gas inward (Correct answer)
Have no meaningful effect on radon entry
Reduce radon entry compared to pressure equilibrium

Correct answer: Increase radon entry by driving soil gas inward

A negative indoor-to-soil pressure differential of even a few Pascals is sufficient to drive advective soil gas flow through foundation openings, significantly increasing radon entry.

Question 139: A crawl space mitigation system shows adequate fan operation, but radon levels remain elevated. Which diagnostic finding is MOST likely?

The soil in the crawl space is too dry
The fan exhaust is too close to a window
The vapor barrier has holes, gaps, or is not properly sealed to walls and piers (Correct answer)
The fan is placed too close to the ground

Correct answer: The vapor barrier has holes, gaps, or is not properly sealed to walls and piers

An incomplete vapor barrier allows radon to bypass the system and enter the living space through gaps or unsealed edges.

Question 140: A home with a crawlspace has significantly elevated radon on the first floor. The MOST likely dominant entry pathway is:

Emanation from the wood framing members
Advection of soil gas through openings in the crawlspace floor into the crawlspace air, then into the living area (Correct answer)
Infiltration of outdoor air through first-floor windows
Diffusion through the wood subfloor from radon in the crawlspace

Correct answer: Advection of soil gas through openings in the crawlspace floor into the crawlspace air, then into the living area

Soil gas with high radon concentration enters the crawlspace through openings in the bare soil or through penetrations, accumulates in the crawlspace, and then migrates through gaps in the subfloor into the living space above.

Question 141: How should a post-mitigation test device be positioned relative to the floor?

Between 20 inches and 6 feet above the floor in the breathing zone (Correct answer)
On the floor directly against the exterior wall
Adjacent to the sump pump to detect point-source radon
At ceiling level to capture rising radon gas

Correct answer: Between 20 inches and 6 feet above the floor in the breathing zone

Test devices must be placed in the breathing zone, between 20 inches and 6 feet above the floor, to accurately represent human exposure.

Question 142: What is the primary purpose of the diagnostic assessment performed before designing a radon mitigation system?

To satisfy local permit requirements only
To determine the appropriate sub-slab communication and entry points (Correct answer)
To estimate contractor profit margin
To identify asbestos in the home

Correct answer: To determine the appropriate sub-slab communication and entry points

Diagnostic testing assesses sub-slab communication and soil conditions to guide effective system design.

Question 143: A commercial SSD system's fan is mounted on the rooftop. What is a key advantage of this placement?

Easier access for homeowner maintenance
Lower electrical consumption due to cooler temperatures
Discharge is already at or above roofline, away from occupied zones (Correct answer)
Reduced noise in mechanical rooms

Correct answer: Discharge is already at or above roofline, away from occupied zones

Rooftop fan placement ensures the radon discharge is above occupied levels and away from air intakes, eliminating the need for extended vertical exhaust piping.

Question 144: According to ASTM E2121, what is the maximum allowable indoor air pressure difference created by an SSD system relative to the sub-slab area?

All suction points must maintain exactly -10 Pa
The standard requires no specific limit on indoor-to-sub-slab pressure difference (Correct answer)
SSD systems are prohibited from creating any basement pressure change
The system must not depressurize the basement by more than 1 Pa relative to outdoors

Correct answer: The standard requires no specific limit on indoor-to-sub-slab pressure difference

ASTM E2121 focuses on sub-slab negative pressure extension but does not set a specific maximum limit on indoor-to-sub-slab pressure difference; instead it requires diagnostic verification of effectiveness.

Question 145: The EPA classifies radon as a Group A carcinogen because it is:

Not classifiable due to insufficient data
Known to cause cancer in humans based on sufficient evidence (Correct answer)
Suspected but not confirmed to cause cancer in humans
Possibly carcinogenic based only on animal studies

Correct answer: Known to cause cancer in humans based on sufficient evidence

Group A carcinogens have sufficient human epidemiological evidence linking them to cancer, as established by miner studies.

Question 146: An RMS contractor discovers the post-mitigation test result is 3.2 pCi/L. Per AARST performance standards, the appropriate next step is to:

Declare success and close the job
Install a second fan immediately without retesting
Recommend additional mitigation measures to reach below 2 pCi/L (Correct answer)
Wait 1 year and retest

Correct answer: Recommend additional mitigation measures to reach below 2 pCi/L

A result of 3.2 pCi/L is above the 2 pCi/L performance goal, so additional measures should be discussed with the client.

Question 147: A post-mitigation test result shows 3.8 pCi/L. What is the most appropriate next step?

Discuss system optimization options with the homeowner (Correct answer)
Remove the mitigation system
Declare the system fully compliant
Issue a clearance certificate immediately

Correct answer: Discuss system optimization options with the homeowner

At 3.8 pCi/L the level is just below the EPA action level but still above the 2 pCi/L goal, so optimization should be discussed.

Question 148: Which condition would DECREASE the sub-slab communication necessary for a sub-slab depressurization system to work effectively?

Crushed stone fill beneath the slab
Slab poured directly on native clay soil with no aggregate (Correct answer)
High soil permeability
Coarse gravel drainage layer under the slab

Correct answer: Slab poured directly on native clay soil with no aggregate

Clay soils directly beneath a slab have very low permeability and resist air movement, limiting the extension of a depressurization field from a single suction point.

Question 149: What is a sub-slab depressurization system?

A system that seals cracks in the foundation.
A system that increases pressure under the building.
A system that vents radon from beneath the building using pipes (Correct answer)
A system that filters air in the basement.

Correct answer: A system that vents radon from beneath the building using pipes

A sub-slab depressurization system is a specific type of active radon mitigation system. It involves installing a suction pipe through the concrete slab floor into the gravel or soil beneath. A fan connected to this pipe draws radon-laden air from under the slab and exhausts it safely outside, preventing it from entering the living space.

Question 150: How soon after activating an active radon mitigation system should post-mitigation testing begin?

One year after installation
At least 24 hours after activation, with minimum 48-hour test (Correct answer)
Immediately upon activation
Testing is not required

Correct answer: At least 24 hours after activation, with minimum 48-hour test

Post-mitigation testing should begin at least 24 hours after system activation to allow conditions to stabilize, with a minimum test duration of 48 hours.

Question 151: During winter in cold climates, radon levels in basements often increase because:

Windows and doors are closed, reducing dilution ventilation (Correct answer)
Radium concentration in soil increases in cold weather
Soil becomes more permeable when frozen
Radioactive decay rates increase at lower temperatures

Correct answer: Windows and doors are closed, reducing dilution ventilation

In winter, buildings are tightly closed to conserve heat, which reduces natural ventilation and allows radon to accumulate to higher concentrations.

Question 152: In a commercial basement with a sump pump, what special consideration applies during SSD installation?

The sump pit may serve as a suction point but must be covered with an airtight lid penetrated by the suction pipe (Correct answer)
The sump pump must be relocated outside the building
The sump pit should be permanently sealed before any SSD work begins
No mitigation is required if a sump pump is present

Correct answer: The sump pit may serve as a suction point but must be covered with an airtight lid penetrated by the suction pipe

Sump pits can be effective suction points, but the pit must be sealed with an airtight cover penetrated only by the suction pipe to prevent radon from bypassing the system.

Question 153: Which document should be provided to the client after post-mitigation testing is completed?

A contractor invoice with radon levels noted in the margin
A written report including test results, device information, testing conditions, and mitigation system details (Correct answer)
An oral summary of findings during a follow-up phone call
Only the fan manufacturer's warranty

Correct answer: A written report including test results, device information, testing conditions, and mitigation system details

Best practice and many state regulations require a written post-mitigation report documenting all test parameters, device data, and results for the client's records.

Question 154: What does Working Level Month (WLM) measure?

Radon flux from soil measured monthly
The maximum permissible exposure level per month
Cumulative radon progeny exposure over time (1 WLM = 1 WL for 170 hours) (Correct answer)
Monthly average radon concentration in pCi/L

Correct answer: Cumulative radon progeny exposure over time (1 WLM = 1 WL for 170 hours)

One WLM equals exposure to 1 WL of radon progeny for 170 hours (one working month), used to quantify cumulative occupational dose.

Question 155: A homeowner reports that their mitigation fan has become noticeably loud after years of quiet operation. What should the technician inspect?

The exterior finish on the exhaust pipe
The indoor radon concentration level
The crawl space vapor barrier integrity
Fan bearings, motor mounts, and pipe connections for wear, vibration, or looseness (Correct answer)

Correct answer: Fan bearings, motor mounts, and pipe connections for wear, vibration, or looseness

Increased fan noise after quiet operation typically indicates bearing wear, loose motor mounts, or vibrating pipe connections requiring inspection and repair.

Question 156: Which condition would require a contractor to install more than one suction point in a sub-slab depressurization system?

The home has a finished basement
Sub-slab communication testing shows vacuum doesn't extend across all areas from a single point (Correct answer)
The fan selected has a CFM rating above 50
The homeowner requests multiple points for redundancy

Correct answer: Sub-slab communication testing shows vacuum doesn't extend across all areas from a single point

When diagnostic testing reveals that one suction point cannot create adequate pressure differential throughout the entire sub-slab area, additional suction points must be added.

Question 157: What should a contractor do if sub-slab diagnostic testing reveals water-saturated gravel or soil beneath the slab?

Evaluate whether soil depressurization is feasible or consider alternative methods (Correct answer)
Drill additional suction holes to allow water drainage before testing
Increase the fan size to compensate for increased resistance
Proceed with SSD as normal since water does not affect vacuum

Correct answer: Evaluate whether soil depressurization is feasible or consider alternative methods

Water-saturated sub-slab conditions severely limit suction field extension, so the contractor must evaluate alternative approaches such as drainage improvement or different mitigation strategies.

Question 158: What is the recommended safety measure when working with radon mitigation systems in confined spaces?

No special safety measures are required.
Proper ventilation and monitoring are crucial (Correct answer)
Workers should wear protective suits only.
The space should be sealed off completely.

Correct answer: Proper ventilation and monitoring are crucial

Confined spaces can accumulate hazardous gases, including radon, and have limited oxygen. Proper ventilation ensures a continuous supply of fresh air, while monitoring for oxygen levels and hazardous gases protects workers from asphyxiation or exposure to dangerous concentrations. These measures are vital for preventing serious injury or death in such environments.

Question 159: What is the primary reason for drilling multiple diagnostic test holes across a basement floor before finalizing suction point placement?

To map sub-slab communication and identify isolated areas requiring additional suction points (Correct answer)
To measure slab thickness at different points across the floor
To measure radon concentration directly beneath the slab at each location
To check for underground utility pipes or wiring before drilling

Correct answer: To map sub-slab communication and identify isolated areas requiring additional suction points

Mapping sub-slab communication through multiple test holes ensures final suction point locations will provide adequate pressure field coverage throughout the entire foundation.

Question 160: When a mitigation contractor installs a system in a state with a radon licensure program, compliance with state regulations:

Only applies to commercial buildings
Is required in addition to meeting AARST standards (Correct answer)
Is optional if AARST standards are followed
Supersedes all federal guidance

Correct answer: Is required in addition to meeting AARST standards

State licensure requirements are mandatory and must be met alongside national AARST/EPA standards.

Question 161: What is the EPA recommended action level for radon in the United States?

1 pCi/L
4 pCi/L (picocuries per liter) (Correct answer)
20 pCi/L
10 pCi/L

Correct answer: 4 pCi/L (picocuries per liter)

The EPA recommends that homeowners take action to reduce radon levels at or above 4 pCi/L, while also noting that reducing levels below 2 pCi/L is difficult to achieve.

Question 162: What is the primary health risk associated with radon exposure, according to the US Surgeon General and EPA?

Cardiovascular disease
Central nervous system disorders
Kidney damage
Lung cancer (Correct answer)

Correct answer: Lung cancer

The US Surgeon General and EPA identify lung cancer as the primary health risk from radon exposure, making it the second leading cause of lung cancer in the United States after smoking.

Question 163: How does an active radon mitigation system work?

It filters the radon from the indoor air.
It increases the airflow inside the building.
It creates negative pressure to vent radon outside (Correct answer)
It stores radon in a safe place.

Correct answer: It creates negative pressure to vent radon outside

An active radon mitigation system, typically an active soil depressurization system, works by using an electric fan to create a continuous negative pressure (vacuum) beneath the building's foundation. This negative pressure draws radon gas from the soil before it can enter the home and then vents it safely to the outdoors, usually above the roofline.

Question 164: Which respiratory protection is considered the minimum for a radon mitigation specialist working in a crawl space with high radon levels and possible mold?

N95 filtering facepiece respirator
Powered air-purifying respirator (PAPR)
Half-face APF-10 respirator with P100 filters (Correct answer)
No respirator is needed for short-duration tasks

Correct answer: Half-face APF-10 respirator with P100 filters

A half-face respirator with P100 particulate filters provides adequate protection against mold spores and particulate hazards encountered in crawl space environments.

Question 165: Radon-222 has a half-life of approximately 3.8 days. If a sealed container starts with 800 pCi, how much remains after 7.6 days?

50 pCi
100 pCi
400 pCi
200 pCi (Correct answer)

Correct answer: 200 pCi

7.6 days equals two half-lives: 800 → 400 → 200 pCi.

Question 166: The ANSI/AARST standard for mitigation in multifamily housing is designated as:

ANSI/AARST CC-1000
ANSI/AARST SGM-SF
ANSI/AARST MAMF (Correct answer)
ANSI/AARST MAH

Correct answer: ANSI/AARST MAMF

ANSI/AARST MAMF specifically addresses radon mitigation practices for multifamily buildings.

NRPP Radon Mitigation Specialist (RMS) Exam

The NRPP Radon Mitigation Specialist exam certifies professionals in the design, installation, and verification of radon mitigation systems for residential and commercial buildings, based on ANSI-AARST standards SGM-SF and MAH.

165

Questions

180 min

Time Limit

70%

To Pass

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