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Air Quality Monitoring & Standards Flashcards

7 cards from real CES practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. The Air Quality Index (AQI) is calculated using which set of pollutants?

    Answer: PM2.5, PM10, O3, CO, SO2, NO2

    The AQI is computed for six pollutants: PM2.5, PM10, ground-level ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide, with the highest sub-index reported.

  2. In dispersion modeling, the Pasquill-Gifford stability classes range from A to F, where class A represents:

    Answer: Extremely unstable daytime conditions

    Pasquill-Gifford class A denotes extremely unstable atmospheric conditions (strong insolation, low wind speed), leading to rapid vertical mixing and dilution of pollutants.

  3. Which monitoring siting criterion in 40 CFR Part 58 Appendix E specifies the minimum distance a monitor must be from a roadway to measure neighborhood-scale PM2.5?

    Answer: 25 meters

    For neighborhood-scale PM2.5 monitoring, 40 CFR Part 58 Appendix E requires the probe inlet to be at least 25 meters from the nearest road edge to avoid direct traffic emission impacts.

  4. What is a 'design value' in the context of NAAQS compliance?

    Answer: The statistically derived ambient concentration used to compare against a NAAQS

    A design value is the ambient air quality statistic — derived from monitoring data per EPA-specified averaging and calculation procedures — compared against the NAAQS to determine attainment status.

  5. Continuous Emission Monitoring Systems (CEMS) for SO2 at large point sources must meet performance specifications under:

    Answer: 40 CFR Part 75

    40 CFR Part 75 establishes the continuous emission monitoring requirements and performance specifications for SO2, NOx, and CO2 at electric generating units and other large sources.

  6. Which chemical reaction is primarily responsible for the formation of ground-level ozone in urban areas?

    Answer: NOx + VOCs + sunlight → O3

    Ground-level ozone forms when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight through a series of photochemical reactions.

  7. A Summa canister used in Method TO-15 must be certified to what vacuum level before field deployment?

    Answer: Less than 0.5 mm Hg absolute

    TO-15 Summa canisters must be cleaned and evacuated to less than 0.5 mm Hg absolute pressure to ensure no residual contamination before sampling ambient VOCs.