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Particulate matter in ambient air and mortality: toxicologic perspectives
Laura C Green1, Sarah R Armstrong
1Cambridge Environmental, 58 Charles Street, Cambridge, MA 02141, USA. Green@CambridgeEnvironmental.com
Regulatory Toxicology and Pharmacology : RTP
|November 19, 2003
Summary
Current U.S. air quality standards for fine particulate matter (PM2.5) may not be supported by evidence. Research suggests moderate PM2.5 concentrations are unlikely to cause significant disease or death.
Area of Science:
- Environmental Health
- Toxicology
- Epidemiology
Background:
- U.S. regulations on outdoor respirable particulate matter (PM), especially PM2.5, assume current levels cause mortality and illness.
- Reducing PM concentrations is believed to save lives.
Purpose of the Study:
- To evaluate the causal link between current ambient PM concentrations and mortality/morbidity.
- To assess the scientific evidence supporting U.S. PM regulations.
Main Methods:
- Review of toxicologic and clinical inhalation studies.
- Analysis of studies using concentrated ambient particles, diesel exhaust, and sulfate/nitrate salts.
- Evaluation of epidemiologic studies for confounding factors and consistency.
Main Results:
- Toxicologic data indicate U.S. ambient PM concentrations are too low to cause significant disease or death.
- Inhalation studies found no evidence that moderate PM concentrations are lethal.
- Epidemiologic studies have weak, inconsistent mortality risk estimates and fail to control for confounders.
Conclusions:
- The scientific evidence does not support the expectation that reducing ambient PM2.5 in the U.S. will save lives.
- Other justifications for regulating PM may exist, but current mortality/morbidity claims are not well-supported.