CEM Air Quality Management & Monitoring 2 — Questions and Answers
Question 1: Which measurement approach is used in the EPA Federal Reference Method (FRM) for ambient PM2.5 monitoring?
- Flame ionization detection (FID)
- Gravimetric filter-based sampling (Correct answer)
- Chemiluminescence analysis
- Ultraviolet photometric detection
Correct answer: Gravimetric filter-based sampling
The EPA FRM for PM2.5 uses gravimetric filter-based samplers that physically collect particles on a pre-weighed filter, which is then re-weighed to determine mass concentration.
Question 2: Which EPA-approved method is primarily used to measure total particulate matter (filterable) emissions from a stationary source stack?
- EPA Method 9 (visible emissions)
- EPA Method 5 (particulate matter) (Correct answer)
- EPA Method 25A (total hydrocarbons)
- EPA Method 7E (NOx)
Correct answer: EPA Method 5 (particulate matter)
EPA Method 5 is the reference method for determining total particulate matter emissions from stationary sources by isokinetic sampling and gravimetric analysis.
Question 3: Continuous Emission Monitoring Systems (CEMS) are most commonly required for facilities subject to which Clean Air Act program?
- Minor source general permits
- Acid Rain Program (Title IV) and other major source requirements (Correct answer)
- Mobile source emission standards only
- Area source registration programs
Correct answer: Acid Rain Program (Title IV) and other major source requirements
CEMS are mandated for major sources under programs such as the Acid Rain Program (Title IV) and certain Title V requirements to provide continuous, real-time emission data.
Question 4: Which EPA-preferred regulatory dispersion model is used to estimate ground-level pollutant concentrations from stationary sources?
- AERMOD (Correct answer)
- SCREEN3
- CAL3QHC
- CALINE4
Correct answer: AERMOD
AERMOD is the EPA's preferred steady-state atmospheric dispersion model for regulatory air quality impact assessments from stationary sources, incorporating modern planetary boundary layer concepts.
Question 5: The 'bubble concept' in air quality regulation allows a facility to:
- Exceed permit limits during startup and shutdown events
- Average emissions across multiple emission points within a facility to meet an overall emission limit (Correct answer)
- Purchase emission offsets from facilities in other states
- Delay compliance schedules for new emission standards by five years
Correct answer: Average emissions across multiple emission points within a facility to meet an overall emission limit
The bubble concept treats all emission units at a facility as if they were enclosed in a single 'bubble,' allowing emissions trading among units as long as the total facility emissions meet the aggregate limit.
Question 6: What does 'opacity' measure in the context of visible emission monitoring?
- Concentration of sulfur dioxide in a stack gas stream
- The degree to which particulate emissions block the transmission of light (Correct answer)
- Temperature of exhaust gases exiting a stack
- Velocity of gas flow through an emission control device
Correct answer: The degree to which particulate emissions block the transmission of light
Opacity is a measure of how much emitted smoke or particulate matter reduces the transmission of light, serving as a surrogate indicator of particulate emission density under EPA Method 9.
Question 7: Under EPCRA Section 313, facilities must submit a Toxics Release Inventory (TRI) report detailing:
- Only accidental releases of extremely hazardous substances
- Annual releases and off-site transfers of listed toxic chemicals above threshold quantities (Correct answer)
- Monthly ambient air monitoring data for criteria pollutants
- Hazardous waste generation and disposal volumes only
Correct answer: Annual releases and off-site transfers of listed toxic chemicals above threshold quantities
EPCRA Section 313 requires covered facilities to annually report to EPA and states the quantities of listed toxic chemicals released to air, water, and land, and transferred off-site, above applicable reporting thresholds.
CEM Air Quality Management & Monitoring 2
Which measurement approach is used in the EPA Federal Reference Method (FRM) for ambient PM2.5 monitoring?