The Clean Air Act (CAA) is the comprehensive federal law that regulates air emissions from stationary and mobile sources. Among other things, this law authorizes the EPA to establish the National Ambient Air Quality Standards (NAAQS) to protect public health and welfare and to regulate emissions of hazardous air pollutants.
The Clean Air Act was last amended in 1990 and requires the EPA to set National Ambient Air Quality Standards (NAAQS) for wide-spread pollutants from numerous and diverse sources considered harmful to public health and the environment. The Clean Air Act established two types of (NAAQS). Primary standards set limits to protect public health, and Secondary standards set limits to protect public welfare. The Clean Air Act requires periodic review of the science upon which the standards are based and to revise the standard as dictated by the scientific analysis.
EPA defines an area or county meeting a given NAAQS standard as an "attainment area" for that standard. If it doesn't meet the standard, it is designated as a "non-attainment area".
The statements and/or data contained on this Web Site are for informational purposes only and not represented to be error free. While every effort is made to ensure this information is up-to-date and accurate, official information can be found on the Web sites of the US Environmental Protection Agency, California Air Resources Board and/or other appropriate regulatory agencies. This Web Site should not be used as a substitute for competent legal advice from a licensed professional attorney in your state or jurisdiction.
Nitrogen dioxide (NO2) is one of a group of highly reactive gasses known as "oxides of nitrogen," or "nitrogen oxides (NOx)." NO2 can be formed
naturally by lightening strikes, from plants and soil, however it is also formed through the internal combustion process that uses air as the oxidant.
Ozone is found in two regions of the Earth's atmosphere, in the upper regions where it prevents damaging ultraviolet light
from reaching the Earth's surface, and ground level . Both ground level and upper region ozone has the same chemical
The 8-hour ozone standard was last revised in 2008 from .084 to.075 parts per million. EPA undertook the process of
EPA Ozone (O3) Home Page:
Particulate matter is a term used to describe a mixture of a complex group of fine airborne solid particles and liquid droplets (aerosols) which includes components of nitrates, sulfates, elemental carbon, organic carbon compounds, acid aerosols, trace metals, and geological material.
On December 14th, 2012 the EPA concluded a revision of the PM2.5 fine particle standard. The results of the revision include:
EPA Particulate Matter Home Page: