The major danger from air pollution is one of health. Most of us know that carbon monoxide in a closed garage can kill us but fewer know of the indirect dangers. For air pollution affects the health of millions who are unaware of its threat. In the absence of precise and overwhelming medical findings, there has been a reluctance to state that air pollution is a cause of lung and circulation diseases or cancer. Medical experts point out that on the basis of current information, they cannot tell whether a pollutant causes a disease. They do, however, admit that air pollution places an additional load on those suffering from other diseases. And they agree that many pollutants severely restrict the oxygen carrying qualities of our blood, reducing our ability to fight other diseases.