Which statement best describes CO2's status with respect to criteria pollutants under NAAQS?

Which statement best describes CO2's status with respect to criteria pollutants under NAAQS?

• A. CO2 is not designated as a criteria pollutant under the NAAQS.
• B. CO2 is a criteria pollutant with a specific ambient limit.
• C. CO2 is a criteria pollutant with the same limits as O3.
• D. CO2 is a criteria pollutant requiring LAER.

Answer: (A)

Under the NAAQS, only a fixed list of pollutants is tracked as criteria pollutants, with ambient standards set for those substances. Carbon dioxide isn’t on that list, so there’s no NAAQS ambient limit or related control requirement for CO2 within this program. LAER (the lowest achievable emission rate) and similar NSR/PSD controls apply to criteria pollutants, not to CO2 under the NAAQS framework. So CO2 isn’t designated as a criteria pollutant under NAAQS, which is why the correct statement is that CO2 is not designated as a criteria pollutant under the NAAQS.

Under the NAAQS, only a fixed list of pollutants is tracked as criteria pollutants, with ambient standards set for those substances. Carbon dioxide isn’t on that list, so there’s no NAAQS ambient limit or related control requirement for CO2 within this program. LAER (the lowest achievable emission rate) and similar NSR/PSD controls apply to criteria pollutants, not to CO2 under the NAAQS framework. So CO2 isn’t designated as a criteria pollutant under NAAQS, which is why the correct statement is that CO2 is not designated as a criteria pollutant under the NAAQS.