The first studies conducted to evaluate a possible association between air pollution and mortality date back to the serious events that occurred in the Mosa Valley, Belgium (1930), in the small city of Donora ("killer fog" incident of 1948) and in London (1952). The latter episode led to the introduction of air pollution control policies. Following the introduction of air pollution control measures in economically advanced cities in the 60s and 70s, the concentration levels of pollutants reached were believed, for many years, to be risk free. However, despite improvements in air quality achieved by many industrialized countries the negative effects of air pollution remain today an important public health problem. Among all air pollutants, particulate matter is the type of air pollution that causes the most numerous and serious effects on human health, because of the broad range of diverse toxic substances it contains,. For this reason, when assessing human health risk, PM10 may be considered to be a reliable indicator of the impact of global air pollution. Various epidemiologic studies conducted in the last 10 years, such as the Air Pollution and Health-European Approach (APHEA) project, the National Morbidity, Mortality and Air Pollution (NMMAPS) Study and Italian Meta-analysis of Studies on the short-term effects of Air pollution (MISA), have shown that current ambient concentrations of PM10 may lead to increased mortality and morbidity. Various studies have reported mean increases in mortality below 1% for 10 ?g/mc increases of ambient PM10. Studies have also underscored the role of particulate matter in aggravating cardiorespiratory diseases and consequently increasing hospital admissions. Air quality standards have been recently revised by legislation. The EU has issued a directive that sets limiting values and, where appropriate, threshold values, for the different air pollutants.