CEA Air Emission Monitoring & Control 3 — Questions and Answers
Question 1: Which control technology is most effective for removing fine particulate matter (PM2.5) from industrial exhaust streams?
- Cyclone separator
- Wet scrubber using water spray only
- Fabric filter (baghouse) (Correct answer)
- Gravity settling chamber
Correct answer: Fabric filter (baghouse)
Fabric filters (baghouses) achieve collection efficiencies exceeding 99% for fine particulate matter, outperforming mechanical separators and simple wet scrubbers for PM2.5.
Question 2: Under the EPA's New Source Performance Standards (NSPS), what regulatory concept triggers applicability when a facility makes a 'major modification'?
- Prevention of Significant Deterioration (PSD) review (Correct answer)
- New Source Review (NSR) only for non-attainment areas
- Title V operating permit revision
- Emergency variance from the state air agency
Correct answer: Prevention of Significant Deterioration (PSD) review
A major modification at a major stationary source in an attainment area triggers PSD review under the NSPS framework, requiring BACT analysis and air quality impact assessment.
Question 3: An environmental auditor reviewing a facility's CEMS records finds that the monitor was out of service for 12% of the operating hours in a quarter. What is the likely regulatory concern?
- The facility exceeds the maximum 5% downtime allowance under 40 CFR Part 75
- The missing data must be substituted using conservative default values per QA/QC protocols
- Both A and B are likely concerns (Correct answer)
- No concern; monitors are allowed unlimited downtime if repairs are documented
Correct answer: Both A and B are likely concerns
Excess monitor downtime above the allowed threshold (typically 5% under Part 75) is a violation, and missing data periods require substitution with conservative values, making both regulatory concerns valid.
Question 4: What does the opacity standard of 20% (6-minute average) primarily regulate under EPA Method 9?
- The concentration of PM10 in ambient air
- The visual obscuration caused by particulate-laden exhaust from a stack (Correct answer)
- The sulfur content of fuel burned in the boiler
- The efficiency of electrostatic precipitators
Correct answer: The visual obscuration caused by particulate-laden exhaust from a stack
EPA Method 9 visual opacity is a surrogate measure of particulate emissions, assessing the degree to which stack exhaust obscures light as observed by a trained, certified observer.
Question 5: Which of the following best describes Selective Catalytic Reduction (SCR) as an NOx control technology?
- It removes NOx by injecting ammonia or urea into the flue gas upstream of a catalyst (Correct answer)
- It reduces NOx by recirculating cooled flue gas back to the combustion zone
- It converts NOx to nitrogen and water using a non-thermal plasma
- It absorbs NOx in a caustic scrubbing solution
Correct answer: It removes NOx by injecting ammonia or urea into the flue gas upstream of a catalyst
SCR systems inject ammonia (or urea that hydrolyzes to ammonia) into exhaust gas, where it reacts with NOx over a catalyst to produce harmless nitrogen gas and water vapor.
Question 6: What is the significance of the 'Class I area' designation under the Clean Air Act for an air quality permit applicant?
- The area is in nonattainment for ozone and requires offsets
- Visibility and air quality receive the highest level of protection, imposing stricter PSD increment limits (Correct answer)
- The applicant is exempt from BACT requirements if located outside the area
- Emissions from Class I areas are not counted toward regional emission inventories
Correct answer: Visibility and air quality receive the highest level of protection, imposing stricter PSD increment limits
Class I areas (such as national parks and wilderness areas) have the most stringent PSD increment limits to preserve air quality and visibility, affecting nearby source permit conditions.
Question 7: During a source test, a facility's measured NOx emission rate is 0.10 lb/MMBtu. The permit limit is expressed as 0.15 lb/MMBtu. Which statement is correct?
- The facility is in noncompliance and must install additional controls
- The facility is in compliance with 33% margin below the permit limit (Correct answer)
- The test must be repeated because the result is more than 20% below the limit
- Compliance cannot be determined without concurrent CO measurements
Correct answer: The facility is in compliance with 33% margin below the permit limit
Measured NOx of 0.10 lb/MMBtu is below the permit limit of 0.15 lb/MMBtu, demonstrating compliance with approximately a 33% margin.
CEA Air Emission Monitoring & Control 3
Which control technology is most effective for removing fine particulate matter (PM2.5) from industrial exhaust streams?