Strong evidence has accumulated from epidemiological and observational studies for a close association between several different air pollutants and adverse health effects, particularly for the residents of metropolitan areas. Although our understanding of the pathophysiological mechanisms involved remains incomplete, there are abundant data which link short-term exposure to air pollution, due to high concentrations of particulate and gaseous matter, toxic metals and aldehydes, with a significant increase in acute cardiopulmonary mortality, particularly in certain high-risk subsets of the population and with an acute increase in hospital admissions for cardiovascular and pulmonary diseases. Furthermore, there is also convincing evidence that prolonged exposure to elevated levels of air pollutants is responsible for chronic ill effects that significantly reduce overall life expectancy. Thus, it is of paramount importance for regulatory agencies to force the implementation of relevant regulations and quality standards in order to protect the health of the population at large. Specific guidelines should also apply for activity restriction for vulnerable and high-risk persons, such as the very young and the elderly, and those with known cardiopulmonary disease or diabetes mellitus
