Air conditioners save lives, especially as the summer time has been getting way hotter over the past couple of years. Many areas — like North America and Europe — are known to experience at least a temperature of 104° F and sometimes a lot more. Without air conditioning that could be lethal.
This may make it seem like air conditioning is really good, yes, it may be great for the hot summer days, but is it exactly healthy? It turns out it may not be.
Lack of air conditioning can be a death sentence
Summer days have gotten increasingly hot in places like Dallas, Texas, for instance, where people are prepared for temperatures of at least 104° F (40° C) and even much higher, already five people have died from the summer heat. In Philadelphia, the figure is even higher, 25. However, in places that have little or no summer cooling at all, however, the effects of summer heat are almost unimaginably devastating.

Air conditioning can be a life or death necessity for some people. But it can also be a source of minor illness for many others, especially the most vulnerable who need cooling the most. People who spend most of the summer in air conditioned homes and offices, could face health consequences. The researchers at Cardiff University in Wales and the New York University Langone Medical Center tell us, are at increased risk for colds and other upper respiratory infections in summer months.
Colds Not Caused By Cold
Repeated exposure to cold air after coming in from severe heat is not, Dr. Ujwala Kaza at New York University is quoted as telling the New York Times, the cause of summer colds. Summer colds are caused by colds viruses, just as are winter colds. Air conditioning, however, makes infection more likely.Increased rates of upper respiratory infection in air conditioned offices is a well known phenomenon. A study published in 1998 in the journal International Archives of Occupational and Environmental Health found that "sick building syndrome," which the authors interpreted as the use of air conditioning rather than natural ventilation in offices in northeastern France, could triple the number of summer colds among office workers. A study published in 2004 in the International Journal of Epidemiology, found that women who work in air conditioned offices in Paris saw doctors about colds and flu more often and also had more skin problems.
One reason for increased infection in air conditioned homes and offices is very simple. The process of cooling air dries it out.
Lower humidity in homes and offices dries out the sinuses, nasal passages, and throat. Tiny fissures open in the mucous membranes as they lose moisture, providing easy entry to viruses and bacteria, and reducing circulation of the bloodstream and immune system to fight infection.
Also, dirty filters can harbor the viruses that cause colds. Researchers at the Harvard University of Public Health have found that as the carbon dioxide content of the air inside an air conditioned building increases, more and more rhinoviruses survive in the air. Clean filters admit more oxygen from outdoors to fight the virus, while dirty filters provide just enough of an air barrier to keep the virus healthy and infectious.
Air Conditioning and Vitamin D Deprivation
A more insidious effect of spending the summer indoors to escape the heat may be vitamin D deprivation. Vitamin D deficiency is usually associated with limited exposure to sunlight during winter, but people in hot-summer areas who have air conditioning are actually more susceptible to vitamin D deficiency than people who live farther north where summer sun is welcome.

In the United States, vitamin D deficiency is especially severe in the Southeast, and especially among persons of African-American descent. The darker the skin, the less vitamin D it makes from sunlight. African-Americans in the American Southeast are not only more likely to suffer summer colds and flu, they are also more likely to suffer osteoporosis, kidney disease, and cancer, in part due to vitamin D deprivation.
What can you do to prevent the negative effects of air conditioning on your health without running the risk of heat stroke? Here are five simple remedies.
1. If you simply cannot stand the heat, stay indoors, but take a vitamin D supplement. For as little as US $0.10 a day, you can get the vitamin D your body needs to maintain the immune system and build healthy bones.
2. Make sure you clean the air filters for your air conditioner at least once a month, or as often as the manufacturer recommends. Bacteria that cause sinus infections can live in air filters, and viruses that cause colds and flu thrive in the slightly higher carbon dioxide levels that build up when outside air comes in through dirty filters.
3. Avoid dry air indoors. You don't want to create an environment conducive to the growth of mold, but neither should indoor air be so dry that your skin and sinuses dry out. Use a home humidifier or a vaporizer, like the vaporizer used to treat colds, only to prevent colds. Humidifying the air protects not just your upper respiratory tract but also your skin.
4. Dust regularly. Don't just use a dry cloth or feather duster to clean dusty surfaces. Dry cloths and feather dusters only send the dust back into the air to settle somewhere else. Dust with a product that catches dust and throw it away after use. This minimizes contact with the viruses that cause colds, the bacteria that cause sinus infections, and the allergens that can trigger hay fever and asthma.
5. Try to get at least 20 minutes of sun every day. It is OK to get sun in the morning until about 10 o'clock even without sunblock, and if you use sunblock, your skin cannot absorb the ultraviolet rays it needs to make vitamin D. Make sure at least your hands and face are exposed to the sun. If your religion requires you to cover your face when you leave your home, get some sunlight in a private location daily.
- O'Connor A, Really? The Claim: Air Conditioning Can Cause Colds, New York Times, 25 July 2011.
- Preziosi P, Czernichow S, Gehanno P, Hercberg S. Workplace air-conditioning and health services attendance among French middle-aged women: a prospective cohort study. Int J Epidemiol. 2004 Oct, 33(5):1120-3. Epub 2004 Aug 19.
- Teculescu DB, Sauleau EA, Massin N, Bohadana AB, Buhler O, Benamghar L, Mur JM. Sick-building symptoms in office workers in northeastern France: a pilot study. Int Arch Occup Environ Health. 1998 Jul, 71(5):353-6.
- Photo courtesy of Atomic Taco on Flickr: www.flickr.com/photos/atomictaco/3760550287/