The health effects of air pollution have been subject to intense study in recent years. Exposure to pollutants such as
airborne particulate matter and ozone has been associated with increases in mortality and hospital admissions due to
respiratory and cardiovascular disease. These effects have been found in short-term studies, which relate day-to-day
variations in air pollution and health, and long-term studies, which have followed cohorts of exposed individuals over
time. Effects have been seen at very low levels of exposure, and it is unclear whether a threshold concentration exists
for particulate matter and ozone below which no effects on health are likely. In this review, we discuss the evidence
for adverse effects on health of selected air pollutants.