They consist of a wide range of organic and inorganic compounds distributed among the gaseous and particulate phases. These particles have hundreds of chemicals adsorbed onto their surfaces, including many known or suspected mutagens and carcinogens. The gaseous phase contains many irritants and toxic chemicals. Oxides of nitrogen, which are ozone precursors, are among the combustion products in the gaseous phase. There is a likelihood for humans to be exposed to diesel emissions or their atmospheric transformation products in both ambient and occupational settings.
Diesel emissions have the potential to cause adverse health effects.
These effects include cancer and other pulmonary and cardiovascular diseases. However, diesel engines are only one of many sources of ambient particulate matter and gaseous air pollutants. Therefore, it is difficult to measure the exposures from various sources, and to distinguish the potential health risks attributable to exposure to diesel exhaust from those attributable to other air pollutants. For over a decade, HEI has supported a broad-based research program to evaluate the health risks of diesel emissions, including investigations of carcinogenesis, modeling studies, and emissions characterization. The purpose of this Special Report is to examine what is known, not known, and still uncertain about the health risks of exposure to diesel emissions.