Is Air-Conditioning Bad For You?

If you're blessed enough to have air-conditioning in your house, at some point in the summer you've probably parked your body directly in front of your A/C unit and wondered if it's possible to overdose on cold air. Sure, not having air-conditioning could be dangerous (or unthinkable) on sweltering days. But is blasting the A/C bad for you?

Not necessarily, says Clifford Bassett, MD, founder and medical director of Allergy and Asthma Care of New York, author of The New Allergy Solution. In fact, if you're someone who has indoor allergies, having A/C could actually help filter out some of the pollen, mold, and pollution that's in the air, which could make your symptoms more tolerable, Dr. Bassett says.

It can be helpful to find an A/C system that actually has a special anti-allergen filter built-in, says Denisa Ferastraoaru, MD, attending physician, Allergy and Immunology, Montefiore Health System. Dr. Bassett adds that you should make a point to actually clean your air-conditioner's filter according to the instructions that come with it. "If you're not on top of it, and don't change the filter, you could have dust mites, mold, or pollen just sitting there," he says.

Air-conditioners can also help decrease the humidity in the air, which can be helpful for people who have asthma or mold allergies, Dr. Bassett says. "In the summer, humidity can be problematic for some people," he says. But again, you have to actually clean your A/C so you don't grow more mold, according to the Allergy and Asthma Foundation of America.

In some cases, if you live in an apartment building, the air might be recirculated through the ducts from one apartment to another, Dr. Ferastraoaru says. "Potentially bringing different allergens — dust, cat, and dog dander — which may worsen your symptoms," she says. So you might want to get an air purifier if your A/C is aggravating your allergy symptoms.

When you're in your office building or out running errands, there's not a whole lot you can do to control whether or not the air-conditioning is clean. In very extreme cases, the water in air conditioning units for large buildings can contain a type of bacteria called Legionella, according to the Centers for Disease Control. And if humans come into contact with Legionella — via the A/C, plumbing, or faucets — it can cause Legionnaires disease, according to the CDC.

According to the CDC, there were 6,000 cases of Legionnaires in the U.S. in 2015. To give you a sense of the severity, one in 10 people who get sick from Legionnaires will die, but most healthy people who are exposed to the bacteria won't end up getting Legionnaires at all, according to the CDC. Although it sounds really scary, the good news is that home and car air-conditioners don't use water to cool the air, so they aren't at risk, according to the CDC.

But what about the extreme temperature change? You know, when you go from the sweltering outdoors into your freezing office — does that have any health ramifications? Many large buildings will keep the air-conditioning very high (meaning: very cold), which can make people uncomfortable, particularly when it's so hot outside. But even though it can be annoying to dress for two varying climates, it's actually not bad to go from one extreme temperature to another. "Normally, the human body is able to adjust its temperature based on the environment temperature," Dr. Ferastraoaru says.

For some people with nasal allergies or sinus issues, though, the change in temperature or humidity can irritate their nasal membranes, Dr. Bassett says. And that irritation or inflammation could case a runny nose, or rhinitis, which isn't a huge deal, he says. People with other chronic medical problems, such as diabetes or a spinal injury, or who take certain medications might also not be able to adjust to the temperature fluctuations as easily, Dr. Ferastraoaru says.

The bottom line: Air-conditioning is not bad for you, and in some cases it could actually be good for you. According to the CDC, air-conditioning is the number one protective factor against heat-related illnesses and death, so it's not something you should skimp on if you have access and can afford it. Intense heat is more than just an annoying environmental factor you have to deal with in the summer, and it can impact your health in serious ways. So, go ahead and crank your A/C till the end of summer — it's cool.