Exposure to coarse air pollution not associated with hospital admission for respiratory diseases

There were 3.7 million cardiovascular disease and 1.4 million respiratory disease admissions from January 1999 through December 2005. A 10-µg/m3 increase in PM10-2.5 was associated with a 0.36 percent increase in cardiovascular disease admissions on the same day and this association was statistically significant. However, when adjusted for PM2.5, this association was no longer statistically significant (0.25 percent). A 10-µg/m3 increase in PM10-2.5 was associated with a nonstatistically significant unadjusted 0.33 percent increase in respiratory disease admissions and a nonstatistically significant 0.26 percent increase in respiratory disease admissions when adjusted for PM2.5. The unadjusted associations of PM2.5 with cardiovascular and respiratory disease admissions were 0.71 percent for same-day exposure and 0.44 percent for exposure 2 days before hospital admission.

There were no statistically significant differences in the regional average effects of PM10-2.5 for either outcome. There were no significant associations of PM10-2.5 or PM2.5 and cause-specific cardiovascular disease and respiratory disease outcomes.

“The National Ambient Air Quality Standard (NAAQS) for particulate matter proposed by the U.S. Environmental Protection Agency (EPA) in 2005 would have replaced the daily PM10 standard with a daily PM10-2.5 standard, but that proposed standard was not retained in the final proposal because of a need for further evidence. Currently, national evidence concerning the health risks of short-term exposure to PM10-2.5 is limited, although there is long-standing recognition of how size influences patterns of deposition within the respiratory tract. We did not find statistically significant associations between same day PM10-2.5 concentration and emergency hospital admissions for cardiovascular or respiratory diseases when we adjusted for PM2.5,” the authors write.

“Nevertheless, we recommend that these findings be considered when the NAAQS for particulate matter is next reviewed, and that the monitoring of PM10 continue so that further studies can be performed.”

(JAMA. 2008;299[18]:2172-2179. Available pre-embargo to the media at www.jamamedia.org)

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