Types of Air Pollutants Read pages 27-35 in your study guide. Read through the section on each individual pollutant making sure you know the major sources, atmospheric processes and means for removal of these pollutants in the earth's atmosphere. Particles produced by combustion are much smaller than those produced by mechanical means and so have longer residence times in the atmosphere. Make sure to visit the Particulate Matter Home Page with links to all sorts of things related to PM in the atmosphere. Photochemical Oxidants Photochemical oxidants are produced due to photochemical smogs.
Plants are very sensitive to ozone and PANs.
100 ppb ozone is enough to cut the rate of photosynthesis by more than half. Large areas of cop plants have been affected in this way because the products of photochemical smogs drift up to 150 km or more from their source to rural areas. Background levels are less than 0.1 ppm. Hydrocarbons Hydrocarbons are best considered as methane and non-methanic hydrocarbons. Methane Methane is produced almost entirely by micro-organisms under anaerobic conditions such as those prevailing in wetlands and in the stomachs of ruminant animals.