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Health risks from bacteria and fungi in automobile interiors

You wash it, wax it, vacuum up the crumbs and wipe off the muddy shoe prints. But no matter how clean you keep your car, there may still be bacteria and fungi lingering in its heating and air-conditioning system, putting you and your family at risk for potential health problems.

Hidden dangers

"Sick car syndrome" isn't one of those sneaky hidden dangers - as the fungi or mold grows, its warning sign is quite clear. If you turn on the air conditioner and a bouquet reminiscent of manure or spoiled cabbage comes wafting out, you've got it.

For the past three years, Robert Simmons, Ph.D., of Georgia State University's Environmental Research Centre in Atlanta, has been studying the problem, which afflicts vehicles in every class from economy to luxury. The offending organisms are similar to the mold and fungus that could grow anyplace (e.g., your shower or home air-conditioning system), but since cars are out on the road, many additional contaminants are introduced. "You can't prevent a problem if you don't understand how it develops in the first place," says Simmons. "The root cause has not been defined yet, but if we can understand how it gets started, then we can pass prevention ideas on to the designers and engineers."

Industry experts cite new vehicle design as the cause. "To increase AC system efficiency, they've made systems with more surface area," explains Paul Deguiseppi, manager of service training at the East Greenville, Penn.-based Mobile Air Conditioning Society Worldwide. "And the more surface area you have, the more space there is for moisture, and for this junk to grow on." While Simmons hasn't yet found any fungi that pose actual infectious disease situations, he is convinced that certain people are at risk for potential health problems. "If you're allergic to these fungi, you can have an allergy attack; if you have a mold sensitivity or asthma, they can bring on an asthma attack." Simmons learned firsthand the effects of driving a sick car when he got a headache every time he drove a "spoiled cabbage" test car to and from work.

Some experts in the automotive industry, like Ward Atkinson, chairman of the Interior Climate Control Standards Committee based in Pittsburgh, downplay the problem. But Simmons insists it's not wise to write the situation off as just an "odour that causes discomfort," as Atkinson does. "Anytime you're dealing with microbiology, it's rarely cut-and-dried," Simmons says. And according to Allan Magaziner, D.O., a specialist in nutrition, allergy and preventive medicine in Cherry Hill, NJ, USA, and the author of The Complete Idiot's Guide to Living Longer and Healthier (Alpha Books, 1999), exposure to the types of fungi Simmons collected from car air-conditioning vents could cause such reactions as headaches, weakness, fatigue and cold or flulike symptoms - at the least.

"Everyone has a certain amount of tolerance to everything we come in contact with. But at some point our ability to withstand it breaks down, so if you're exposed to fungi and bacteria at home and in the car, your body might become so overwhelmed that you become ill," he says. Spraying disinfectant into the air vents won't kill these growths. "The chances of anything making it into the system and still being effective are somewhere between slim and none," says Simmons. The best solution, he says, is to clean out the evaporator. But since that's such a time-consuming and expensive job, he explains there's another option: "Correctly applied by a technician, an antimicrobial treatment such as the MiST™ will fix the problem the majority of the time."

Tips To Help Keep Your Car's Interior Mold Free . . .
  • Regularly replace Cabin Air Filters and speak to your technician about getting a MiST™ treatment at the same time to rid the vehicle of existing mold and bacteria.
  • Air-conditioning should be run on the "outside air" setting, as opposed to the re-circulated setting as often as possible. This allows the system to pull in new air and get rid of old moisture (which reduces the chances of contamination).
  • The "max" setting is going to give you re-circulated air and should only be used on very hot days-and only until you get comfortable.
  • Never leave the A/C set on "max" while the engine is off. This keeps the vents closed and doesn't allow outside air to get in. The heat created by a closed system combined with the moisture produces a virtual greenhouse for bacteria and fungi.
  • When you use the A/C, there should be water draining from under the car. No water runoff means that the drain hole is blocked and the evaporator is not drying out, creating a perfect breeding ground for bacteria and fungi.


Due to increasing demand for the MiST™ service, TerraClean™ is recruiting a Sales Agent/Representative in the Halifax area. Please contact: Al Esposito by calling 514-220-5080 or by email:

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