Air Pollution - Natural Causes Page
(all photographs by J. Gerencher)

Nature also introduces solids, liquids, and gases into the atmosphere.  Volcanic eruptions and forest fires are two obvious sources of such "pollutants."  People with allergies will be aware of spores and pollen as well.  Below are some others that may not have come immediately to mind.

In the left photo below, lava flows enter the sea and create hydrochloric acid fumes by chemically reacting with the salt water.  The people in the picture provide a sense of scale.  Island of Hawaii.

The right photograph above shows that downwind the hydrochloric acid fume clouds descend to land surface, from the upper left to the center of the right picture.  The land is barren of vegetation because of young age of the lava, but also because of the toxic effects of the acidic mist that is deposited on the surface downwind of the lava flow/sea interface.  People in the picture provide some sense of scale.  Island of Hawaii.

Great Smoky Mountains named for haze
due to tree hydrocarbon emissions.
North Carolina / Tennessee