‘Criteria pollutants’ is the name given to a group of emissions including carbon monoxide (CO), nitrogen oxides (NOX), nonmethane volatile organic compounds (NMVOCs), and sulfur dioxide (SO2). Due to their contribution to the formation of urban smog and in the case of SO2, acid rain, these pollutants are regulated by the Clean Air Act. These gases have an indirect effect on global warming by reacting with other chemicals in the atmosphere to form those compounds that are greenhouse trace gases. They also contribute to the formation of tropospheric ozone, which has negative effects on human health.
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Sources |
Emission Processes |
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Carbon Monoxide 57% of criteria pollutant emissions
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CO is produced and released when carbon- containing fuels are combusted incompletely. Remember that carbon- containing fuels include natural gas, coal and petroleum products such as gasoline. These are burned during the production of electricity and for transportation purposes. |
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Nitrogen Oxides 16% of criteria pollutant emissions |
Lightning and fires can create this group of pollutants naturally. NOX can also be created by combustion of fossil fuels and by nitrous oxide in the stratosphere. |
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Sulfur Dioxides 14% of criteria pollutant emissions |
Sulfur dioxides are created and released during the combustion of fossil fuels and the metals industry. |
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Nonmethane Volatile Organic Compounds (NMVOCs) 13% of criteria pollutant emissions |
NMVOCs are mainly emitted from transportation vehicles, industrial processes, and the use of organic solvents. NMVOCs include propane, butane, and ethane. |
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