Indoor Air Quality (IAQ) and Allergens
What this domain tests
IAQ and allergens tests whether you can identify sources, evaluate ventilation and filtration, and recommend controls in the right order: source control, ventilation, then air cleaning.
Core rules
- Common indoor allergens include dust mites, pet dander, cockroach allergen, pollen, and mold. Dust mites and mold need moisture control; pets and pests need source and cleaning controls.
- ASHRAE 62.1-style ventilation supplies outdoor air for occupants. CO2 is a ventilation indicator, not a direct toxin measure. High CO2 suggests inadequate outdoor air if occupancy and calibration are known.
- Filtration uses MERV ratings; higher MERV captures more particles but must match fan capacity and pressure drop.
- Keep indoor RH roughly 30-50% where possible. Excess humidity supports mites and mold; over-drying causes discomfort.
- Combustion appliances need venting and CO alarms. VOCs and formaldehyde come from furnishings, cleaners, and building materials.
- Investigate occupant complaints with interviews, walkthroughs, moisture and CO/CO2 measurements, and HVAC inspection.
Worked example
A classroom reports stuffiness; CO2 reads 1,800 ppm with 30 students. Reasoning: this is a ventilation indicator. Check outdoor-air damper, fan operation, and occupancy schedule before blaming a pollutant. Increasing outdoor air and verifying airflow is the first control; a portable purifier is supplemental.
Traps
- Treating an air purifier as a substitute for ventilation or source control.
- Interpreting a single CO2 reading without occupancy or calibration data.
- Ignoring combustion safety and CO.
- Recommending humidity below 30% or above 50% without justification.
- Assuming all odors are mold.