Air Quality (Outdoor [Ambient] and Indoor)

Ambient air pollution consists of a complex mixture of gases, particulate matter, and liquids. The air pollutants include the six criteria pollutants, toxic air pollutants, and greenhouse gas emissions, which affect human health, the environment including the various ecosystems, and the stratospheric ozone layer. The Clean Air Act protects the stratospheric ozone layer by phasing out the production and release of chemicals that can cause ozone layer problems. The US Environmental Protection Agency (EPA) through its National Air Toxics Assessment Program conducts a comprehensive evaluation of the major 33 air toxics found in the ambient air of the United States. The broad response is that the Clean Air Act has helped build the economy and create jobs while reducing pollution to protect the health of citizens and the environment. The air toxics were found throughout the Portland region and were especially high in highly populated areas, near busy roads in areas where there was substantial business and industrial activity.