globail warming,deforestration
the major source is the burning of fossil fuels
factories and cars
Natural air pollution sources include: volcanoes (SO2, CO2, ash) forest fires (CO2) Pine forests (turpenes) dust storms (particlate) anaerobic decomposition (methane) lightning (ozone, NOx) ozone...
The largest source of human-caused air pollution is the burning of fossil fuels. 90% of air pollution is from power plants and automobiles.