Understanding Air Pollution
A Reference Guide To The Major Criteria Pollutants
Air pollution affects all living things. It causes health problems in humans and animals, damages plants, kills fish, pollutes water, eats away at infrastructure and reduces visibility. It can also lead to acid rain, global warming and smog.
Currently, there are air quality standards set on six criteria pollutants. These standards were established in the Clean Air Act Amendments of 1970. They are based on currently available scientific data and health studies.
EPA has taken many actions to improve air quality. National air quality levels measured at thousands of monitoring stations across the country have shown improvements over the past 20 years for all six principal pollutants. Since 1970, aggregate emissions of the six principal pollutants have been cut 48 percent. During the same time there have been great increases in U.S. gross domestic product, energy consumption, and vehicle usage.
Despite this improvement, approximately 146 million people live in counties where air was unhealthy at times because of high levels of at least one of the six principal air pollutants. The vast majority of areas that experienced unhealthy air did so because of one or both of two pollutants – ozone and particulate matter (PM).
Important efforts continue to be underway to control these pollutants include implementing more protective National Ambient Air Quality Standards (NAAQS) for ozone and PM and issuing rules to reduce emissions from on-road transportation and stationary combustion sources. (All of the following information was taken from the EPA web site.)
Six Criteria Pollutants
Of the six pollutants identified by the EPA as being important in controlling emissions levels, four can be considered related to mobile emissions control, and two are not:
- Mobile emissions related pollutants:
- Non-mobile (primarily stationary industrial) emissions related pollutants: