CMAQ
CMAQ is an acronym for the Community Multi-scale Air Quality Model,[1][2] a type of atmospheric dispersion model developed by the US EPA to address regional air pollution problems. (For example, a multi-state area where ozone or fine particulate levels exceed the US health standards.) Secondary formation of air pollution occurs when air pollution forms by chemical reactions in the atmosphere. For example, ozone forms in the atmosphere when nitrogen oxides interact with volatile organic compounds in the presence of sunlight. Ammonium sulfate is a fine particle that is formed when ammonia and sulfur dioxide react in the atmosphere.[3] Meteorological conditions such as subsidence inversions, decrease the amount fresh air available for dilution of air emissions, and increase the rate of production of secondary air pollutants. CMAQ has the capability to accurately predict air pollution concentrations resulting from secondary formation. Like any air dispersion model, CMAQ inputs air pollutant emissions and meteorological data and outputs air pollutant concentrations. Its particular strength is in assessing the efficacy of regional emissions control strategies in reducing regional air pollution levels.