Air pollution is a serious problem in our society these days. We come across it indoors, when people have been smoking, and outdoors, where motor vehicle exhaust pollutes the air. For years scientists have been warning us that polluted air is a hazard to our health. It seems these warning are not being taken acutely enough. The truth is that air pollution is growing worse, especially in compactly populated societies. We must for that reason take instantaneous action to progress the quality of air we breathe.