Gases fill the atmosphere such as ozone, sulfer dioxide, nitrogen dioxide, and carbon monoxide. Some things that create air pollution are factories, volcanoes, wildfires, exhaust from vehicles, dust, pollen, and mold spores. All of this stuff can also cause acid rain.
There is a solution to air pollution, and that solution is decreasing the use of fossil fuels in transportation, manufacturing and electricity generation which contributes to better human and environmental health and also slows down global warming.
My city has used the solution to air pollution and everything is back to normal again.