AQS Cheat Sheet 2026

The 30 highest-yield AQS facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. When should a risk register be updated? → Continuously as new risks emerge and existing risks change
2. Why is staying current with industry developments important for Air Quality Specialist professionals? → To provide the best possible service using current knowledge and practices
3. Stage II vapor recovery systems at gasoline service stations are designed to capture which pollutant during vehicle refueling? → Volatile organic compounds (VOCs) / gasoline vapors
4. Which EPA program specifically regulates stationary source emissions of ozone-depleting substances under Title VI of the Clean Air Act? → Stratospheric Ozone Protection Program
5. What is the primary advantage of using a continuous emissions monitoring system (CEMS) over periodic stack testing? → CEMS provide real-time, 24/7 emissions data for operational control and compliance
6. The Emergency Response Planning Guidelines (ERPGs) are developed and published by which organization? → American Industrial Hygiene Association (AIHA)
7. What is a common indoor source of air pollution? → Tobacco smoke
8. Under EPA 40 CFR Part 75, a SO2 CEMS must complete a Relative Accuracy Test Audit (RATA) at what minimum frequency? → Annually
9. Residential wood combustion is regulated primarily because it emits significant amounts of which pollutant? → Fine particulate matter (PM2.5)
10. Green infrastructure elements like urban trees and vegetated roofs help mitigate urban air quality primarily by: → Removing PM and ozone through dry deposition and stomatal uptake
11. During natural attenuation monitoring for a BTEX plume, which field parameter most directly indicates active aerobic biodegradation? → Decreasing dissolved oxygen near the contaminant source
12. How does tree planting help improve air quality? → Absorb air pollutants and CO2
13. Which section of the Clean Air Act governs the permitting of major sources through the Title V Operating Permit Program? → Title V (Sections 501-507)
14. In EPA Method 18, what technique is used to measure volatile organic compound concentrations in stationary source emissions? → Flame ionization detection after gas chromatographic separation
15. Which EPA document (40 CFR Part 58 Appendix A) establishes network design and QA requirements for the SLAMS ambient air monitoring network? → Quality Assurance Requirements for SLAMS, PAMS, and NCore Monitoring
16. What is a benefit of switching from coal to natural gas in power generation? → Reduces air pollutant emissions
17. What role does solar radiation play in ground-level ozone formation? → It provides energy to drive photochemical reactions between NOx and VOCs
18. In a bioventing system for petroleum hydrocarbon remediation, the primary goal of air injection is to: → Supply oxygen to stimulate indigenous aerobic microorganisms
19. Which industrial process is the dominant anthropogenic source of sulfur dioxide (SO2) emissions in the United States? → Fossil fuel combustion at electric utilities
20. What are National Ambient Air Quality Standards (NAAQS) designed to do? → Limit pollutants to safe levels
21. What is the primary use of a continuous emissions monitoring system (CEMS)? → Measure stack emissions in real time
22. Multi-phase extraction (MPE) is advantageous over standard SVE at sites where: → Low-permeability soils trap both NAPL and dissolved phase near the water table
23. In air dispersion modeling, 'effective stack height' is defined as the sum of the physical stack height plus: → Plume rise due to momentum and buoyancy of exhaust gases
24. In source apportionment studies using receptor modeling, what type of data input does a Chemical Mass Balance (CMB) model require? → Ambient receptor concentrations and chemical source profiles of emission sources
25. UV fluorescence technology is the Federal Reference Method (FRM) measurement principle used for which criteria pollutant? → Sulfur dioxide (SO2)
26. What should a practitioner do when regulations conflict with employer policies? → Follow the regulation, as legal requirements supersede employer policies
27. Which CAA section establishes the operating permit program requiring large sources to obtain comprehensive Title V permits? → Section 502
28. What role do scrubbers play in air pollution control? → Capture pollutants from exhaust gases
29. Building downwash in air dispersion modeling occurs when stack emissions are captured by the aerodynamic wake created by: → The source building or nearby structures
30. What is the most important principle in professional Air Quality Specialist practice? → Maintaining competence through continuous learning and adherence to standards