The chilling way your air conditioner could be making you sick

You might want to stick to a fan on those ultra-hot summer days (Thinkstock)
You might want to stick to a fan on those ultra-hot summer days (Thinkstock)

Recent record-breaking temperatures, heat waves and wildfires raging across much of the country have sent us fleeing inside to the cool, clear relief of the air conditioner. These refreshing fans go beyond helping us beat the heat; they are lifesavers for the elderly and infirm by not only keeping them cool, but by filtering out airborne pollutants that can drift in through open windows.

“They do quite a bit to improve air quality and protect health during [excessive] heat and smog, and for wildfire smoke, which can affect breathing,” says Dr. Bonnie Henry, deputy provincial health officer for the B.C. Ministry of Health in Victoria. “Well-maintained A/Cs can filter out pollens and irritants as well as insects, and they can reduce the risk of dehydration.”

But there’s another side to air conditioners that’s not so cool: Older, damaged or poorly-installed or maintained units in your home, car and workplace can become contaminated and potentially harmful, making you sick or exacerbating existing health problems. At the very least, they can dry out your skin, prompting you to reach for the moisturizer all day long. “They can also have a drying effect on the lining of the nose and throat, especially if they are set too cold and humidity is low,” says Dr. Henry. “And that can lead to an irritation cough or increased susceptibility to infections in some people.”

A/Cs can also aggravate low blood pressure, arthritis and neuritis, an inflammation of the optic nerve.

At the very worst, poorly maintained, installed or damaged air conditioners can be life-threatening. “There have been some outbreaks of the bacteria legionella [which can cause legionnaires’ disease, a serious respiratory illness that leads to pneumonia] related to building chillers in particular that are not well-maintained,” says Dr. Henry.

Dr. Mark Mendell, an epidemiologist with the California Department of Public Health, has studied the health effects of air conditioning systems and says contaminated units can worsen asthma and allergies. He says the process of cooling hot air creates a lot of moisture and condensation, which must be channeled away. If your unit is damaged, poorly maintained or designed, it can become a breeding ground for bacteria, fungi and mould, circulating germs and micro-organisms that cause breathing problems. In fact, researchers at Louisiana State Medical Center found eight types of mould living inside 22 out of 25 the cars they tested.

And while “sick building syndrome” is not as common a problem as it was in the 1970s and ‘80s due to Canadian Standards Association guidelines regarding maintenance standards of heating, ventilating and air-conditioning (HVAC) systems, says Dr. Henry, those who are very sensitive or have existing conditions, and who spend long hours in artificially cooled environments can still suffer from nasal congestion, breathing problems, headaches, fatigue and irritated skin caused by micro-organisms growing in the units.

“Proper maintenance of the A/C, ensuring the temperature is not too cold, and that humidity sits around 60-70 per cent help,” says Dr. Henry. “As well, buildings should be ventilated regularly by having the air exchanged with fresh air. And people who are sick should stay away and/or cover their mouth when they cough to avoid the recirculated air carrying the virus to others.”

In addition, says Dr. Henry, spending many hours in an air-conditioned environment affects how your body adjusts to the heat over time, making you less tolerant of hot summer temperatures. Also, constantly moving from cool indoor air to hot outside air puts a lot of stress on the body.

From an environmental standpoint, while hydrochlorofluorocarbons (HCFC-22) have replaced the ozone-destroying chlorofluorocarbon (CFC) refrigerant of the 1990s, they are still considered ozone-depleting, according to Environment Canada, and will be phased out by 2020 to meet The Montreal Protocol.

Dr. Stan Cox, senior scientist at The Land Institute in Salina, Kan., and author of Losing Our Cool: Uncomfortable Truths About Our Air-Conditioned World, says in his website of the same name,, “Turning buildings into refrigerators burns fossil fuels, which emits greehouse gases, which raises global temperatures, which creates a need for — you guessed it — more air-conditioning.” He acknowledges the health benefits of A/Cs during extreme heat, but says we shouldn’t justify using them everyday for months on end. He says we should return to our pre-air conditioned world: flip on the fan, embrace the slower pace of summer, take a siesta, or reduce work hours — even close the office occasionally. What a cool idea.

How to maintain your cool

If your air conditioner can save your life, you’ll need to save the life of your air conditioner. Here are some tips from Natural Resources Canada for maintaining it and using it judiciously.

  • If you can, cut down on your costs and consumption by using your air conditioner only when absolutely necessary. To keep cool air in and hot air out, caulk and weatherstrip your windows to seal air gaps, and insulate your exterior walls. Use awnings, blinds and drapes to block direct sunlight, but don’t cover the unit’s vents with drapes, carpets or furniture. Plant deciduous trees on the south and west sides of your house for shade. Use your kitchen range fan when cooking and bathroom fan while showering to reduce moisture buildup. Use energy-efficient appliances and lighting to reduce heat emissions.

  • Mount your unit on a north-facing or shaded wall.

  • Is it necessary to cool the entire house or just one or two rooms? Designating as few spaces as possible as “cool rooms” will save money and energy.

  • Use the highest setting (25.5°C is recommended) for comfort. If you’re not using the room for an extended period, turn it up to 28°C and completely off if the room is unoccupied for 24 hours or more. Never use your A/C with an open window or exterior door.

  • Clean the coil and air filters at least once a year, before the cooling season, to promote air flow and reduce compressor damage.

  • Keep leaves and other dirt and debris off the condenser.

  • Regularly check and clean drain holes and tubes.

  • If the unit is not operating optimally, have it serviced for leaks, particularly to avoid releasing hydrochlorofluorocarbon refrigerant into the atmosphere, which is illegal in some provinces and territories (and will soon be the case nationally).

  • Clean and lubricate the furnace fan and outdoor unit fan according to your owner’s manual. At the same time, check and adjust, if necessary, the furnace fan speed for peak performance.

  • Reduce or eliminate leaks by keeping all ducts sealed with proper sealant. Have the fan motor periodically oiled, if necessary.

  • Leave the serious electrical or mechanical checks and refrigerant level maintenance to the professionals. Deal with companies that have the proper training and equipment for refrigerant recovery and recycling.