AQS AQS Indoor Air Quality 2 — Questions and Answers
Question 1: Biological contaminants in indoor air quality include all of the following EXCEPT:
- Mold spores
- Dust mite allergens
- Radon gas (Correct answer)
- Legionella bacteria
Correct answer: Radon gas
Radon is a radioactive gas, not a biological contaminant; mold, dust mites, Legionella, and pollen are examples of biological (microbial and allergen) indoor air contaminants.
Question 2: The primary control strategy for reducing mold growth in buildings is:
- Increasing temperature to 85°F
- Controlling moisture and relative humidity below 60% (Correct answer)
- Installing HEPA filters
- Applying biocide sprays monthly
Correct answer: Controlling moisture and relative humidity below 60%
Mold requires moisture to grow; maintaining indoor relative humidity below 60% (ideally 30–50%) and promptly addressing water intrusion is the most effective mold prevention strategy.
Question 3: HEPA filters used in air purifiers are required to remove at least what percentage of particles ≥ 0.3 micrometers?
- 95%
- 97%
- 99.97% (Correct answer)
- 90%
Correct answer: 99.97%
By definition, a HEPA (High Efficiency Particulate Air) filter must capture at least 99.97% of airborne particles with a diameter of 0.3 micrometers or larger.
Question 4: What is the purpose of a blower door test in the context of indoor air quality?
- Measuring radon levels
- Quantifying building air leakage to assess infiltration and ventilation (Correct answer)
- Detecting carbon monoxide sources
- Determining HVAC filter efficiency
Correct answer: Quantifying building air leakage to assess infiltration and ventilation
A blower door test depressurizes a building to measure its air leakage rate (expressed in ACH50 or CFM50), informing decisions about ventilation adequacy and contaminant infiltration pathways.
Question 5: Legionella pneumophila, the bacterium causing Legionnaires' disease, most commonly spreads indoors through:
- HVAC duct particulates
- Aerosolized water droplets from contaminated cooling towers or hot water systems (Correct answer)
- Direct person-to-person contact
- Contaminated food preparation surfaces
Correct answer: Aerosolized water droplets from contaminated cooling towers or hot water systems
Legionella thrives in warm water systems (cooling towers, hot water tanks, decorative fountains) and becomes an inhalation hazard when contaminated water is aerosolized into fine droplets.
Question 6: The EPA's Indoor Air Plus label program encourages construction practices that address:
- Only radon and carbon monoxide
- A comprehensive set of indoor pollutant sources including moisture, combustion, radon, pests, and ventilation (Correct answer)
- Outdoor air pollution entering buildings
- Workplace OSHA chemical exposure limits only
Correct answer: A comprehensive set of indoor pollutant sources including moisture, combustion, radon, pests, and ventilation
EPA Indoor airPLUS is a voluntary new-home construction program with specifications covering moisture control, combustion safety, radon mitigation, pest management, HVAC filtration, and ventilation.
AQS AQS Indoor Air Quality 2
Biological contaminants in indoor air quality include all of the following EXCEPT: