B

A type of hydrocarbon, such as benzene or toluene, added to gasoline in order to increase octane. Some aromatics are toxic.

 

The taking up or assimilation of one substance by another, where the two substances chemically combine.

The adhesion of a thin film of liquid or gas to a solid substance.

A colloidal system in which the dispersed phase is composed of either solid or liquid particles, and in which the dispersion medium is some gas, usually air. Generally less than one micrometer in size.

Any air pollutant for which an NAAQS does not exist (i.e. excluding ozone, carbon monoxide, PM-10, sulfur dioxide, nitrogen dioxide) that may reasonably be anticipated to cause cancer, developmental effects, reproductive dysfunctions, neurological disorders, heritable gene mutations or other serious or irreversible chronic or acute health effects i [..]

The growth of a particle by collision with and assimilation of other particles. Ordinarily, the connotation is that all particles are solid.

The composition of air with respect to quantities of pollutants therein; used most frequently in connection with "standards" against which the contribution of the particular source can be compared.

Area An area considered to have air quality as good as or better than the NAAQS as defined in the Clean Air Act. An area may be an attainment area for one pollutant and a non-attainment area for others.