Created in the atmosphere when oxides of nitrogen combine with reactive organic gases in the presence of sunlight. These reactive organic gases are primarily generated by auto emissions, but industrial emissions as well. Once in the lungs, ozone generates a free radical, an oxygen atom, that irritates lung tissue—causing or exacerbating asthma, emphysema, respiratory disease and, over time, reduced lung capacity. Animal studies also indicate that ozone either causes or exacerbates cancers.
Everyone knows carbon monoxide as a colorless, odorless gas that comes out of the tailpipes of cars which, by blocking the delivery of oxygen to the blood, can kill you. But carbon monoxide in smaller doses causes dizziness, impairs central nervous system functioning, deprives the heart muscles of oxygen—leading to heart attacks, and is also a reproductive toxin.