Ozone and short-term mortality in 95 US urban communities, 1987-2000.
BACKGROUND
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.


METHODS
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.


METHODS
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.
Bell
Michelle L
ML
School of Forestry and Environmental Studies, Yale University, New Haven, Conn 06511, USA. michelle.bell@yale.edu
McDermott
Aidan
A
Zeger
Scott L
SL
Samet
Jonathan M
JM
Dominici
Francesca
F
D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis / Q000706:statistics & numerical data; D006801:Humans; D009026:Mortality; D010126:Ozone / Q000009:adverse effects* / Q000032:analysis; D014481:United States / Q000453:epidemiology; D014505:Urban Population / Q000706:statistics & numerical data*; D014887:Weather
D010126:Ozone