Turning on the A/C can be a huge relief on the hottest day of the year, but you may also wonder if the air circulating around the room might be doing more than just cooling you down. When it comes to air conditioning's effects on your body, it's overall a pretty positive picture, experts say.
"It stands to reason that air conditioning can affect human health, especially if the air conditioning system is not closely monitored and maintained regularly," Dr. Seema Sarin, M.D., director of lifestyle medicine at EHE Health, tells Bustle.
A/C can be good for your health in that it can make it easier to sleep when it's hot. "The best temperatures for sleeping are between 62 and 72F," Dr. Janette Nesheiwat, M.D., a family and emergency physician, tells Bustle. One study published in Energy & Buildings in 2017 found that people tend to roll over or show small signs of wakefulness when the fan switches on, but that it doesn't affect their sleep quality negatively.
Living and working in the heat isn't great for your brain. A study by Harvard in 2018 published in PLOS Medicine found that, in hot summers, students who lived in dormitories without A/C did worse on cognitive tests than those who had cool, refreshing central air — particularly in the afternoons, when the outside world began to cool but their dorms were still absolutely roasting. "When the body cannot cool off on its own, it can be dangerous in high temperatures," Nesheiwat says.
It has a lot of pluses, Sarin says, mainly in keeping you cool on sweltering days, but it can also have its drawbacks.
Suddenly going from sweltering heat to freezing air-conditioning, whether it's your house, work, or car, can be a strain on your body. One study published in Clinical & Translational Allergy in 2018 found that doing that transition regularly can harm your lungs, making you more vulnerable to respiratory illnesses. Nesheiwat points out that too much cold can be a bad thing. "Prolonged cold air can cause contracture of the muscles, which can lead to joint pain and aches, which can be exacerbated if you are dehydrated," she says. Too much freezing air can also make asthma worse and dry out the mucus membranes in your mouth and nose.
Sarin says that if you're experiencing dry skin, dry eyes, or dehydration, and you work and live in air-conditioned environments, central air may be affecting your health. "Many of these health symptoms are due to a lack of fresh air, lack of moisture in the air, or the recirculation of air in an environment that contains pollutants," she says. And it can be worse if you have allergies. Dr. Natasha Bhuyan, M.D., regional medical director for One Medical, tells Bustle that dust mites, pollen, dander, and mold can get trapped inside your A/C's filters and get released when it turns on. A/C has also been linked to coronavirus, but the relationship isn't crystal clear; one study published in Emerging Infectious Diseases in 2020 linked an outbreak in Guangzhou, China to the flow of air conditioning in a restaurant, but it's not known whether people should be concerned about exposure to the virus through these means.
If you use the A/C occasionally and make sure they're equipped with filters, though, your lungs may actually thank you. A study of long-term exposure to filtered air in Environmental International in 2018 discovered that it's a good way to filter out airborne pollution, and that's good for your heart and respiratory system. The American Academy of Allergy, Asthma and Immunology recommends changing the filters in your central A/C and in-room air conditioners at least once a month if you're prone to allergies.
Well-maintained, clean air conditioners with air filters look like they're good for your health. If they start smelling funky or you're getting a lot of runny noses, though, it could be time to clean the filters and adjust the settings to be a little less arctic.
Dr. Natasha Bhuyan, M.D.
Dr. Janette Nesheiwat, M.D.
Dr. Seema Sarin, M.D.
Cedeño Laurent, J. G., Williams, A., Oulhote, Y., Zanobetti, A., Allen, J. G., & Spengler, J. D. (2018). Reduced cognitive function during a heat wave among residents of non-air-conditioned buildings: An observational study of young adults in the summer of 2016. PLoS medicine, 15(7), e1002605. https://doi.org/10.1371/journal.pmed.1002605
Chuang, H. C., Ho, K. F., Lin, L. Y., Chang, T. Y., Hong, G. B., Ma, C. M., Liu, I. J., & Chuang, K. J. (2017). Long-term indoor air conditioner filtration and cardiovascular health: A randomized crossover intervention study. Environment international, 106, 91–96. https://doi.org/10.1016/j.envint.2017.06.008
D’Amato, M., Molino, A., Calabrese, G. et al. The impact of cold on the respiratory tract and its consequences to respiratory health. Clin Transl Allergy8, 20 (2018). https://doi.org/10.1186/s13601-018-0208-9
Lu, J., Gu, J., Li, K., Xu, C., Su, W., Lai, Z., Zhou, D., Yu, C., Xu, B., & Yang, Z. (2020). COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2020. Emerging infectious diseases, 26(7), 1628–1631. https://doi.org/10.3201/eid2607.200764
Morito, N., Tsuzuki, K., Mori, I., Nishimiya, H. (2017) Effects of two kinds of air conditioner airflow on human sleep and thermoregulation. Energy and Buildings. 138: 490 DOI: 10.1016/j.enbuild.2016.12.066