How can air pollution cause breathing problems?

Air pollution can aggravate arterial and respiratory problems. A report in the British Medical Journal found that changes in the level of air pollutants -- specifically, ozone and black smoke, a major source of PM2.5 (particulate matter, in the 2.5 micron range or smaller) -- led to an increase in the rates of deaths from all causes, primarily because of an increase of as much as 5 percent in cardiovascular and respiratory aging. Air quality may also have a significant effect on the development of asthma, a disease that affects as many as 20 million Americans.

Recent data show how air pollution produces asthma, and it's quite surprising. Small air particles from the polluted air get deep into the lungs. Even though the immune system responds, the particles impair immune function. That impairment allows infections to occur, which results in asthma. So, pollution doesn't directly produce asthma but, instead, produces immune dysfunction that allows infections to succeed in damaging the lung, which in turn leads to asthma. Asthma rates are increasing in intensely urban areas, such as the inner-city areas of New York and Chicago, suggesting that poor air quality's ability to trigger the onset of asthma is a concern that actually can and does affect and age large numbers of us. Air quality also affects the number of sinus infections and respiratory illnesses that people suffer.