Is Air Conditioning Bad for You?
The biology and ideology of home cooling.
Photograph by Lisa F. Young/Thinkstock.
To read Part 1 of the case against the case against air conditioning, click here.
A few weeks ago, an academic journal called Weather, Climate and Society posted a curious finding about how Americans perceive the heat and cold. A team of researchers at the University of Oklahoma asked 8,000 adults living across the country to state both their political leanings and their impressions of the local weather. Are you a liberal or a conservative? Have average temperatures where you live been rising, falling, or staying about the same as previous years? Then they compared the answers to actual thermostat readings from each respondent's ZIP code. Would their sense of how it feels outside be colored by the way they think?
Yes it would, the study found. So much so, in fact, that the people surveyed all but ignored their actual experience. No matter what the weather records showed for a given neighborhood (despite the global trend, it had gotten colder in some places and warmer in others), conservatives and liberals fell into the same two camps. The former said that temperatures were decreasing or had stayed the same, and the latter claimed they were going up. "Actual temperature deviations proved to be a relatively weak predictor of perceptions," wrote the authors. (Hat tip to Ars Technica for finding the study.)
People's opinions, then, seem to have an effect on how they feel the air around them. If you believe in climate change and think the world is getting warmer, you'll be more inclined to sense that warmth on a walk around the block. And if you tend to think instead in terms of crooked scientists and climate conspiracies, then the local weather will seem a little cooler. Either way, the Oklahoma study suggests that the experience of heat and cold derives from "a complex mix of direct observation, ideology, and cultural cognitions."
It's easy to see how these factors might play out when people make grand assessments of the weather that rely on several years' worth of noisy data. But another complex mix of ideology and culture affects how we experience the weather from moment to moment—and how we choose to cope with it. In yesterday's column, I discussed the environmental case against air conditioning, and the belief that it's worse to be hypothermic than overheated. But there are other concerns, too, that make their rounds among the anti-A/C brrr-geoisie. Some view air conditioning itself as a threat to their comfort and their health.
The notion that stale, recycled air might be sickening or dangerous has been circulating for as long as we've had home cooling. According to historian Marsha E. Ackermann's Cool Comfort: America's Romance With Air-Conditioning, the invention of the air conditioner set off a series of debates among high-profile scholars over whether it was better to fill a building with fresh air or to close it off from the elements altogether. One side argued for ventilation even in the most miserable summer weather; the other claimed that a hot, damp breeze could be a hazard to your health. (The precursor to the modern air conditioner, invented by a Floridian named John Gorrie, was designed according to the latter theory. Gorrie thought his device would stave off malaria and yellow fever.)
The cooling industry worked hard to promote the idea that A/C makes us more healthy and productive, and in the years after World War II it gained acceptance as a standard home appliance. Still, marketers worried about a lingering belief in the importance of fresh air, and especially the notion that the "shock effect" of moving too quickly from warm to cold would make you sick. Some of these fears would be realized in a new and deadly form of pneumonia known as Legionnaires' disease. In the summer of 1976, around 4,000 members of the Pennsylvania State American Legion met for a conference at the fancy, air-conditioned Bellevue Stratford Hotel in Philadelphia, and over the next month, more than 180 Legionnaires took ill. The bacteria responsible for their condition were found to be propagating in the hotel's cooling tower. Twenty-nine people died from the disease, and we finally had proof that air conditioning posed a mortal danger to America.
A few years later, a new diagnosis began to spread around the country, based on a nebulous array of symptoms including sore throats and headache that seemed to be associated with indoor air. Epidemiologists called the illness "Sick Building Syndrome," and looked for its source in large-scale heating and cooling ducts. Even today, the particulars of the condition—and the question of whether or not it really exists—have not been resolved. But there is some good evidence for the idea that climate-control systems can breed allergenic mold or other micro-organisms. For a study published in 2004, researchers in France checked the medical records of 920 middle-aged women, and found that the ones who worked in air-conditioned offices (about 15 percent of the total pool) were almost twice as likely to take sick days or make a visit to an ear-nose-throat doctor.
This will come as no surprise to those who already shun the air conditioner and worship in the cult of fresh air. Like the opponents of A/C from a hundred years ago, they blame the sealed environment for creating a miasma of illness and disease. Well, of course it's unhealthy to keep the windows closed; you need a natural breeze to blow all those spores and germs away. But their old-fashioned plea invites a response that's just as antique. Why should the air be any fresher in summer than winter (when so few would let it in)? And what about the dangers that "fresh air" might pose in cities where the breeze swirls with soot and dust? A 2009 study in the journal Epidemiology confirmed that air conditioning can help stave off the effects of particulate matter in the environment. Researchers checked the health records of senior citizens who did or didn't have air conditioners installed in their homes and found that those who were forced to leave their windows open in the summer—and suck down the dirty air outside—were more likely to end up in the hospital for pollution-related cardiovascular disease. Other studies have found similar correlations between a lack of A/C on sooty days and hospitalization for chronic obstructive pulmonary disease and pneumonia.