CES Air Quality Monitoring & Standards 2

Question 1

Which EPA method is the federal reference method for measuring ambient PM2.5 concentrations?

Accepted Answer

40 CFR Part 50 Appendix L

Answer

40 CFR Part 50 Appendix L specifies the gravimetric filter-based federal reference method for measuring PM2.5 in ambient air.

Question 2

The 24-hour NAAQS standard for PM2.5 was tightened in 2024 to:

Accepted Answer

15 µg/m³

Answer

In February 2024, EPA revised the 24-hour PM2.5 NAAQS from 35 µg/m³ to 9 µg/m³ annual and kept or revised the 24-hour standard to 35 µg/m³, but the annual was lowered to 9 µg/m³; the 24-hour standard remains 35 µg/m³ — however the new 2024 rule set the annual at 9 µg/m³.

Question 3

A PAMS (Photochemical Assessment Monitoring Station) is specifically required to measure:

Accepted Answer

Ozone precursors including VOCs and NOx

Answer

PAMS sites are required to monitor ozone precursors — volatile organic compounds (VOCs) and NOx — to support photochemical modeling and ozone control strategies.

Question 4

What does the term 'attainment area' mean under the Clean Air Act?

Accepted Answer

An area where air quality meets or is better than the relevant NAAQS

Answer

An attainment area is one in which ambient air quality meets the applicable NAAQS for a given pollutant, as determined by EPA based on monitoring data.

Question 5

Which instrument operating principle is used by a TEOM (Tapered Element Oscillating Microbalance)?

Accepted Answer

Change in oscillation frequency of a tapered element as mass accumulates

Answer

A TEOM measures PM mass by detecting changes in the resonant frequency of a vibrating tapered element as particles collect on a filter at its tip.

(CES) Certified Environmental Scientist Practice Test

(CES) Certified Environmental Scientist Practice Test

CES Air Quality Monitoring & Standards 2