Air pollution mask. Cyclist wearing an air pollution mask. The main source of air pollution in cities is from car exhausts. Cars produce harmful gases such as nitrogen oxides, sulphur oxides, carbon monoxide and ozone. They also emit unburnt hydrocarbons, lead fumes and partially burnt microscopic particles of soot. Using a filter, masks like this help to remove the larger pollutants, but gases will still have an effect. It has been shown that there is a higher incidence of bronchitis in areas with heavy air pollution.
Model release available. Property release not required.