Sulphur dioxide mixes with water vapour producing sulphuric acid in the atmosphere. It precipitates along with rain causing acid rain.
Carbon dioxide traps heat and doesn't let it escape. It leads to a gradual increase in tempertaure. This is called greenhouse effect.
Increased levels of carbon monoxide interferes with the ability of red blood cells to distribute O2 (oxygen) which deprives human body of oxygen.
Chlorofluorocarbons (CFC's) once released into the atmosphere, accumulate in the stratosphere, where they contribute to the depletion of the ozone layer.