Ozone and Survival in Four Cohorts with Potentially Predisposing Diseases

Abstract

Rationale: Time series studies have reported associations between ozone and daily deaths. Only one cohort study has reported the effect of long-term exposures on deaths, and little is known about effects of chronic ozone exposure on survival in susceptible populations. Objectives: We investigated whether ozone was associated with survival in four cohorts of persons with specific diseases in 105 United States cities, treating ozone as a time varying exposure. Methods: We used Medicare data , and constructed cohorts of persons hospitalized with chronic conditions that might predispose to ozone effects: chronic obstructive pulmonary disease, diabetes, congestive heart failure, and myocardial infarction. Yearly warm-season average ozone was merged to the individual follow-up in each city. We applied Cox proportional hazard model for each cohort within each city, adjusting for individual risk factors, temperature, and city-specific long-term trends. Measurements and Main Results: We found significant associations with a hazard ratio for mortality of 1.06 (95% confidence interval [CI], 1.03-1.08) per 5-ppb increase in summer average ozone for persons with congestive heart failure; of 1.09 (95% CI, 1.06-1.12) with myocardial infarction; of 1.07 (95% CI, 1.04-1.09) with chronic obstructive pulmonary disease; and of 1.07 (95% CI, 1.05-1.10) for diabetics. We also found that the effect varied by region, but that this was mostly explained by mean temperature, which is likely a surrogate of air conditioning use, and hence exposure. Conclusions: This is the first study that follows persons with specific chronic conditions, and shows that long-term ozone exposure is associated with increased risk of death in these groups.

A rapid assessment of the impact of hazard reduction burning around Sydney, May 2016

“…Some analyses found associations with respiratory mortality and some with all-cause and cardiopulmonary mortality. However, the Zanobetti & Schwartz (2011) study together with toxicological studies (see Question B1) provide further support for the effects of long-term exposures to ozone.…”

“…Since 2005, several cohort analyses (Table 1) have been published; together they suggest an effect of long-term exposure to ozone on mortality, at least for respiratory or cardiorespiratory mortality, especially in people with potential predisposing conditions (Lipfert et al, 2006;Krewski et al, 2009;Jerrett et al, 2009a;Smith KR et al, 2009;Zanobetti & Schwartz, 2011). Generally, these studies do not include ozone exposure from cohort entry to death, and some use limited monitoring data.…”

“…Thus, it seems unlikely that only respiratory deaths are driving the association. To eliminate potential confounding by factors that vary across cities, Zanobetti & Schwartz (2011) studied year-to-year variations in 8-hour mean daily ozone concentrations around the long-term trend in relation to variations in mortality around the mortality trend. Their study focused on cohorts of potentially vulnerable individuals and was limited to the months of May through September.…”

“…Smith KR et al (2009) found associations between ozone and cardiopulmonary mortality to be robust to inclusion of sulfate in a two-pollutant model. Zanobetti & Schwartz (2011) used a metric of mean ozone from May to September, and a mean of "Spring and Autumn". Their findings suggest that long-term exposure to ozone elevates the risk of mortality in different subgroups of susceptible populations (those suffering from congestive heart failure, myocardial infarction, diabetes and chronic obstructive pulmonary disease).…”

Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer

“…A further study by Jerrett et al (2009) using the same cohort found unstable risk estimates for ozone and all-cause, cardiopulmonary and cardiovascular mortality, with only respiratory mortality being associated with ozone after adjustment for PM 2.5 . For a more detailed discussion of these and other recent cohort studies (Smith et al, 2009;Zanobetti and Schwartz, 2011;Lipsett et al, 2011) than space here permits, the reader is referred to the REVIHAAP report.…”