Beijing Car Pollution by Iowahawk
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment, into the atmosphere.
Most cities throughout the world experience dense concentrations of motorized emissions comprising particulate matter, lead, carbon monoxide, nitrogen oxides, and volatile organic compounds that react in the presence of sunlight to form ground-level ozone which poses risks to human health and plant life. Fine particulates, often associated with vehicular emissions, can cause health problems such as premature mortality and morbidity, as well as significant economic damage, and are thus of special concern in the developing world.
Read more in the gTKP Urban Mobility Topic Information Sheet on Air Pollution and Urban Mobility.