-Nitrogen Oxide is acidic. The source is lighting activity and internal combustion engines. It has variety of harmful effects which are forming acid rain when dissolves in rain water & corrodes metal structures & buildings & harmful to crops & marine life. It also cause breathing difficulties.
-Sulfur Dioxide is acidic. The source is volcanoes eruption and combustion of fossil fuels. It has the same harmful effects with nitrogen oxide.
-Carbon Monoxide is neutral. The source is incomplete combustion of carbon containing substances. It may be poisonous that causes blind with red blood cells to form stable compound and cut off oxygen supply in the body.
-Oxide is neutral. The source react with sunlight on air containing hydrocarbons and nitrogen oxides. It cause breathing difficulties.
-Methane is neutral. It's a vegetation decay that causes global warming.
-Unburnned Hydrocarbon is neutral. It's a combustion of fossil fuels that causes global warming.