The air we breath is vulnerable to many contaminants and has during different times in our history experienced great amounts of pollution. In the 70's the skies in the U.S. (particularly California) were becoming muddled and many times had a greyish hue about it. Fortunately air regulations went into effect during the late 70's and early 80's which have helped to bring the blue skies back and have made our air easier to breath. Regardless air pollution still exists as we have millions of cars on the roads, planes in the skies and countless buildings and factories spewing pollution into our atmosphere. We've controlled the pollution to a degree, but dangerous chemicals still float about in our air which can cause any number of illnesses in human beings and other living animals and organisms.
Air pollution is also harmful to our ecosystem. It can kill plants and animals. Polluted air can muddled up our bodies of water thus poisoning fish. Air pollution can and has gone so far as to cause havoc in our ozone which creates climate change. For the past five years glaciers in Iceland have been melting away. As these glaciers melt they can cause much damage to the earth including tsunamis, tidal waves, excessive flooding, rise in temperature and mass destruction.