Dry deposition, or air pollution, contributes large amounts of nitrogen to watersheds . Coastal fogs are another source of nitrogen. Where the watershed covers a much larger area than does the estuary, atmospheric deposition onto the land surface rather than the estuary itself is more important. Pollution of the air we breathe is related to many factors. Climate, humidity, concentration of air pollutants in heavily industrial and densely populated areas, thermal inversion, stagnant air masses, seasonal and perennial airborne pollens, dust, moulds, spores and ozone are a few contributors to the problems we face in the air.
Allergies are pollutants typically caused by naturally occurring airborne particles.
For example, pollens in the spring and fall from grasses, weeds, trees and flowers. Perennial or chronic allergies are due to industrial pollutants, dust, dust mites, animal dander and the like. Ozone is the major contributor to the haze we see over our cities we call smog. Ozone is also created from arc welding, flour bleaching, deodorizing, emissions from copying equipment and photochemical air pollution. Ozone is a mucous membrane irritant and causes irritation of the nose, throat, eyes and lungs.