Air conditioning linked to fewer heart-related hospitalizations.

Bell, ML, K Ebisu, RD Peng and F Dominici. 2009. Adverse health effects of particulate air pollution: modification by air conditioning. Epidemiology doi:10.1097/EDE.0b013e3181aba749.

“No pleasure, no rapture, no exquisite sin greater than central air” goes the quote from the movie Dogma. It turns out that there might just be a scientific basis to that sentiment.

A report published online in the journal Epidemiology finds that communities that have more homes with central air conditioning have proportionately fewer older people who are hospitalized for heart and circulatory problems related to air pollution.

The perceived health benefit was specific for central air conditioning, not window units, and was mainly seen in the summer, which is when air conditioning is typically in full use, rather than in the winter.

When breathed in, small particles in air pollution can irritate lungs, increase asthma symptoms and lead to more severe heart and cardiovascular diseases. The central air conditioning filters the particles from the indoor air and most likely does a better job of it than window units, the authors surmise.

The scientists gathered information on particulate air pollution, cardiovascular and respiratory-related hospital admissions in people age 65 or older and the proportion of homes with air conditioning in communities across the United States. They estimated for each community the extent of hospitalizations related to breathing air that contains microscopic particles of pollution.

They found that in areas with more central air conditioning, relatively fewer older people were admitted to the hospital for cardiovascular problems connected to particulate air pollution. More specifically, for each 20 percent increase in households with air conditioning, the cardiovascular-related hospitalizations due to air pollution were reduced by 43 percent.

This trend did not hold true for respiratory-related hospitalizations due to air pollution.

But, a vicious cycle of energy demand, air conditioning use and air pollution can develop, the researchers explain. More air conditioning use requires more energy. Generating energy leads to air pollution and contributes to global warming, possibly spurring higher use of air conditioning.

So, for the short term, the use of air conditioning may offer the elderly a health benefit. But, it is not clear if long term pollution and climate problems associated with central air conditioning will ultimately lessen that benefit. This may be of particular concern for elderly people who do not have air conditioning.

This study looked at overall rates of particulate air pollution, air conditioner use and hospitalizations for each community. In other words, it looked at the group as a whole rather than comparing individuals. The conclusions would be stronger if air conditioner use, exposure to air pollution, hospitalizations and specific details about health problems were obtained for every person in the group and compared.