What is Visible Air Pollution?

The ambiance is almost entirely made up of invisible gases. Most major air pollutant are invisible, but large amounts of them concerted in areas that cities can be seen as smog. An often visible air contaminants are particulate matter, especially when it surfaces of buildings and other structure have been open to the elements to it for long periods or when it is present in large quantity. Particulate matter consists of tiny particles of solid and / or drops of liquid.Natural sources include volcanic ash, pollen and dust blown by the blustery weather.