Which of the following is NOT a criteria air pollutant?
Methane is an important greenhouse gas and a precursor in atmospheric chemistry, but it is not one of the conventional criteria air pollutants regulated through ambient concentration standards. Lead, carbon monoxide, and ground-level ozone are criteria pollutants because widespread exposure and documented health or environmental effects justify routine monitoring and legally defined limits. Sound classification links the source, atmospheric fate, exposure route, and mechanism of toxicity rather than relying only on the pollutant's name. Effective management combines cleaner fuels, emission sta
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology