Health effects of particles in ambient air.

A summary of a critical review by a working group of the German commission on Air Pollution Prevention of VDI and DIN of the actual data on exposure and health effects (excluding cancer) of fine particulate air pollution is presented. EXPOSURE: Typical ambient particle concentrations for PM10 (PM2.5) in Germany are in the range of 10-45 (10-30) microg/m3 as annual mean and 50-200 (40-150) microg/m3 as maximum daily mean. The ratio of PM2.5/PM10 generally amounts between 0.7 and 0.9. HEALTH EFFECTS: During the past 10 years many new epidemiological and toxicological studies on health effects of particulate matter (PM) have been published. In summary, long-term exposure against PM for years or decades is associated with elevated total, cardiovascular, and infant mortality. With respect to morbidity, respiratory symptoms, lung growth, and function of the immune system are affected. Short-term studies show consistant associations of exposure to daily concentrations of PM with mortality and morbidity on the same day or the subsequent days. Patients with asthma, COPD, pneumonia, and other respiratory diseases as well as patients with cardio-vascular diseases and diabetes are especially affected. The strongest associations are found for PM2.5 followed by PM10, with no indication of a threshold value for the health effects. The data base for ultra fine particles is too small for final conclusions. The available toxicological data support the epidemiological findings and give hints as to the mechanisms of the effects. CONCLUSION: The working group concludes that a further reduction of the limit values proposed for 2005 will substantially reduce health risks due to particulate air pollution. Because of the strong correlation of PM10 with PM2.5 at most German sites there is no specific need for limit values of PM2.5 for Germany in addition to those of PM10.

Fine particles and human health--a review of epidemiological studies.

Adverse health effects of exposure to particles have been described in numerous epidemiological studies. Health endpoints thoroughly studied are all cause and cause-specific mortality, and hospital admissions. Older studies focussed on associations with PM10 (then named fine particles). During the last decade, PM2.5 was increasingly emphasised, and the term "fine particles" was restricted to this size fraction. Currently, ultrafine particles (UF, PM0.1) are discussed to be another important fraction which should be characterised by particle number instead of particle mass. However, data on UF exposure and health effects are still limited. The mechanisms by which particles influence human health are only poorly understood. Under discussion is the role of particle size and particle composition. The risk assessment of coarse particles (i.e. the size fraction between 2.5 and 10 microm) suffers from inconsistent findings. The question of causality is not completely answered. However, it is widely accepted that PM is some kind of container including components which are toxicologically relevant and others which might be seen mainly as indicators. Thus, the local mix may influence the toxicological potency of PM, and results from studies carried out in one region may not necessarily be consistent with results gained elsewhere. Recently, reanalyses of epidemiological studies performed by the Health Effects Institute (HEI) qualitatively confirmed the original results. New insight in the influence of socioeconomic factors extended the knowledge on health effects of particles. To some extent, the slope of the dose response relationships from time-series analyses needed downward adjustment due to some problems with statistical analysis programmes. Nevertheless, the whole body of knowledge supports the role of PM as a type of air pollution with great influence on human health.