AQS Study Guide 2026
Everything you need to pass the AQS exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 AQS Exam Format at a Glance
📚 AQS Topics to Study (69)
✍️ Sample AQS Questions & Answers
1. Which NESHAP provision requires sources to conduct periodic compliance demonstrations using performance tests or monitoring at the frequency specified in the applicable standard?
40 CFR Part 63 NESHAPs specify periodic performance test (stack test) requirements to demonstrate ongoing compliance with HAP emission limits.
2. Which federal regulation requires facilities storing hazardous chemicals above threshold quantities to submit Risk Management Plans that include air quality emergency scenarios?
CAA Section 112(r) established the Risk Management Program requiring RMPs for facilities with listed chemicals above threshold quantities.
3. The mixing height (mixing layer depth) primarily determines what for air quality assessments?
Mixing height defines the vertical extent of the atmospheric boundary layer available for pollutant dilution, directly influencing ground-level concentrations.
4. Which audit type involves an independent organization submitting a known-concentration sample to a laboratory without the laboratory knowing the true value?
A Performance Evaluation Audit (PEA) — also called a blind audit — submits certified reference samples to a laboratory without disclosing the true values, testing actual analytical performance under normal conditions.
5. A company receives a Notice of Violation (NOV) from EPA for exceeding a NSPS limit. What is the maximum civil penalty per day of violation under the Clean Air Act?
The CAA authorizes civil penalties up to $25,000 per day per violation, adjusted for inflation—the current amount is approximately $70,117 per day as of recent updates.
6. A facility installs a biofilter to control odorous hydrogen sulfide (H₂S) emissions. The biofilter's performance depends most critically on maintaining:
Sulfur-oxidizing bacteria require adequate moisture and tolerate low pH, but severe acidification from sulfuric acid byproducts must be controlled to sustain microbial activity.