ABSTRACT

This chapter exclusively deals with the gaseous components of the air pollutants. The three major groups of gaseous air pollutants by historical importance, concentration, and overall effects on plants and animals (including people), are sulphur dioxide, oxides of nitrogen and ozone. Sulphur dioxide and nitric oxide are primary pollutants — they are emitted directly from sources. Catalytic control of air pollutants has been given a prime role in the reduction of motor vehicle emissions; there are also many industrial process emissions that can be reduced by catalytic conversion. Gaseous air pollutants such as organics are captured on the surface of a bed of porous material (the adsorbent) through which the gas flows. There are many air pollutants that may be important in particular situations: fluorine; heavy metals; formaldehyde; and asbestos. Asbestos covers a range of mineral fibres released from building thermal insulation and brake linings. Inhalation of the fibres can result in potentially fatal lung disorders.