The filters are identified by codes such as an N, R or P, which indicate the level of oil resistance offered by the filter. One of the two common types of respirators is the air-purifying respirator. These respirators should be used only where there is sufficient oxygen. Air-purifying respirators remove airborne contaminants as air enters the respirator through chemical cartridges or mechanical filters. The chemical cartridges are filled with activated carbon, which has a very high absorption capacity for gases and vapors.
Mechanical filters provide protection by trapping particulate matter in the fibrous filter material.
It has a fan that pulls air through the filters and circulates it over the wearer's face. Air-purifying respirators vary widely in price. The second basic type of respirator is the atmosphere-supplying respirator. This kind of respirator supplies an independent source of breathable air and is used in conditions where oxygen is deficient or the applicator is exposed to high concentrations of very toxic pesticides in enclosed areas. Breathable air is supplied to the wearer from an independent source through an air line, or the wearer carries oxygen in a tank.