A new report from the US Environmental Protection Agency (EPA) provides compelling evidence to support the introduction of more rigorous exhaust emission standards for diesel engines (see CMAJ 2002;167 [5]:505).
The EPA report, Final Health Assessment Document for Diesel Engine Exhaust (www.epa .gov /epahome /recentadditions .htm), provides a comprehensive review of evidence surrounding the potential health effects caused by ambient exposure to the exhaust from diesel engines currently in use.
The evidence identifies health effects associated with both acute and chronic exposure to diesel exhaust. Short-term exposure can cause irritation (e.g., eye, throat, bronchi), neurophysiologic symptoms (e.g., light-headedness, nausea) and respiratory symptoms (e.g., coughing, phlegm). Chronic exposure to diesel emissions can produce dose-dependent inflammation and histopathologic changes in the lung. “[This] assessment concludes that long-term (i.e., chronic) inhalation exposure is likely to pose a lung cancer hazard to humans, as well as damage the lung in other ways depending on exposure.”
The EPA says the conclusions about potential health problems are based on engines built before the mid-1990s. “The health hazard conclusions, in general, are applicable to engines currently in use, which include many older engines. As new diesel engines with cleaner exhaust emissions replace existing engines, the applicability of the conclusions in this document will need to be re-evaluated.”
In a press statement, the EPA said standards that will take effect in 2007 will reduce emissions from diesel engines by up to 95%. The agency is also helping state and other agencies retrofit older diesel engines to make them run cleaner, and developing model programs to reduce emissions from idling engines. — Erica Weir, CMAJ