Ozone Linked to Higher Death Rates in Large U.S. Multi-City Study
Short-term increases in ozone were found to increase total non-accidental mortality and deaths from cardiovascular and respiratory causes in a large 14-year study of residents of 95 U.S. cities.
The relationship between mortality and ozone was evident even on days when pollution levels were below the current regulatory standard of 80 ppb averaged over 8 hours.
Researchers from Yale and Johns Hopkins University used analytical methods and databases developed for the National Morbidity, Mortality, and Air Pollution Study (NMMAPS) to conduct their investigation.
On average across the 95 urban communities, researchers found a 0.5% increase in daily mortality when there was a 10-ppb increase in the previous week’s ozone concentration. The results indicate a substantial public health burden from ozone air pollution. Study authors estimated that a 10 ppb increase in daily ozone would correspond to an additional 3,767 annual premature deaths in the 95 cities, but this is probably an underestimate because it only considers short-term effects.
The ozone concentrations were not correlated with PM10 in the communities studied. The analysis provided strong evidence against confounding of the effects of these two pollutants. Further, the ozone and mortality results did not appear to be confounded by temperature.
The researchers conclude: “Our findings, interpreted in the context of the already extensive epidemiologic and toxicologic evidence on ozone toxicity, indicate that this widespread pollutant adversely affects mortality, in addition to other health effects that have been associated with ozone.”
Bell ML, McDermott A, Zeger SL, Samet JM, Dominici F. Ozone and short-term mortality in 95 US urban communities, 1987-2000. JAMA 2004; 292:2372-2378.
The National Library of Medicine [www.ncbi.nlm.nih.gov] offers the abstract online.
