Sunday, February 13, 2005

Ozone Kills at Levels Permitted by EPA

BrooklynDodger posts yet another study showing that air pollution permitted by current EPA limits – in this case ozone – causes directly observed increases in deaths in community studies. Key comments of the investigators extracted from the full text are:

"A 10-ppb increase in daily ozone would correspond to an additional 319 … annual premature deaths for New York City and 3767 … premature deaths annually for the 95 urban communities, based on mortality data from 2000. This value is probably an underestimate of the total mortality burden from such an increase in ozone because it accounts for only the short-term effects. Further, we found a relationship between mortality and ozone at pollution levels below the current regulatory standard."

The new EPA limit for ozone is 80 ppb; most communities included in this study had exposure below the EPA limit.

So if EPA and the Administration accepted the results, they would conclude that current regulatory approaches allow too much exposure. Compliance with the NAAQS rule for ozone will still leave behind excess deaths. New source performance rules which might administratively require better control are certainly needed.

This study was accepted through peer review by a top ranked US medical journal – Journal of the American Medical Association – and co authored by a leading epidemiologist.

These studies depend on advanced statistical techniques. These techniques have been extensively reviewed and survived concerted attack by industry.


Ozone and Short-term Mortality in 95 US Urban Communities, 1987-2000

Michelle L. Bell, PhD; Aidan McDermott, PhD; Scott L. Zeger, PhD; Jonathan M. Samet, MD; Francesca Dominici, PhD

JAMA. 2004;292:2372-2378.

Context Ozone has been associated with various adverse health effects, including increased rates of hospital admissions and exacerbation of respiratory illnesses. Although numerous time-series studies have estimated associations between day-to-day variation in ozone levels and mortality counts, results have been inconclusive.

Objective To investigate whether short-term (daily and weekly) exposure to ambient ozone is associated with mortality in the United States.

Design and Setting Using analytical methods and databases developed for the National Morbidity, Mortality, and Air Pollution Study, we estimated a national average relative rate of mortality associated with short-term exposure to ambient ozone for 95 large US urban communities from 1987-2000. We used distributed-lag models for estimating community-specific relative rates of mortality adjusted for time-varying confounders (particulate matter, weather, seasonality, and long-term trends) and hierarchical models for combining relative rates across communities to estimate a national average relative rate, taking into account spatial heterogeneity.

Main Outcome Measure Daily counts of total non–injury-related mortality and cardiovascular and respiratory mortality in 95 large US communities during a 14-year period.
Results A 10-ppb increase in the previous week’s ozone was associated with a 0.52% increase in daily mortality (95% posterior interval [PI], 0.27%-0.77%) and a 0.64% increase in cardiovascular and respiratory mortality (95% PI, 0.31%-0.98%). Effect estimates for aggregate ozone during the previous week were larger than for models considering only a single day’s exposure. Results were robust to adjustment for particulate matter, weather, seasonality, and long-term trends.

Conclusions These results indicate a statistically significant association between short-term changes in ozone and mortality on average for 95 large US urban communities, which include about 40% of the total US population. The findings indicate that this widespread pollutant adversely affects public health.

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