How can your car's air conditioner reduce germs?

Does the air conditioning in your car provide musty, germ-laden air? Some cars now have air purification systems to keep your air fresh.

If you think you have enough to worry about just keeping your house clean and germ-free, think again. Auto makers want to help you keep your car germ-free, too. Several companies have recently added special features to some of their luxury vehicles to protect passengers from airborne germs, pollutants and allergens. These cars maintain their personal hygiene with a high-tech combination of air filters, ionizers and climate control features.

Clean-air systems don't relieve car owners of the responsibility of cleaning inside their cars -- but think how nice it'd be if they did! Most germs get into a car through the doors, not the air filtration system, on hands, feet and food eaten in the car. A study conducted by the Healthy House Institute tested 11 areas inside 100 vehicles across the U.S. The number one site for bacteria? Food spills. Numbers two and three on the list were the dashboard and cup holders. Not surprisingly, family vans had the highest germ count, and warmer, humid environments bred more bacteria.


What these systems can do is keep out most allergens and airborne germs, clear the inside air of contaminants and control humidity to keep bacteria growth to a minimum. To get a better idea of how they do this, let's take a look at the different components of such systems.

Specialized air filter: Most cars have a simple air filter that blocks most particles. Infiniti's Forest Air system filter, impregnated with grapeseed polyphenols, is claimed to be 88 percent more efficient [source: Evans].

Ionizer: To control contaminants that find their way in through open windows and doors, an ionizer emits positive and negative ions that attach to airborne bacteria, viruses and molds, neutralizing them. Toyota uses this technology, called a Plasmacluster ionizer, in its higher-end cars. Volvo goes a step further with its Clean Zone Interior Package, which automatically vents stale, contaminated air from the car when the driver unlocks it.

Humidity control: Some cars' clean-air systems generate a small amount of humidity to counteract the drying effect of air conditioning. Infiniti's system, for example, keeps humidity in a narrow range that's more comfortable for passengers, but not for germs.

This is great for people who own or are planning to buy one of these cars. But what about the rest of us? Check your owner's manual or call the manufacturer to find out what kind of cabin filter is installed in your car. If it's a standard particulate filter, it's fairly inexpensive to upgrade to a HEPA (high efficiency particulate air) filter, which removes 99.97 percent of airborne particles that are 0.3 microns or more in diameter [source: U.S. Department of Energy]. And make sure you replace your filter regularly, according to the manufacturer's recommendations; old filters can be less efficient and even start to grow mold.

To learn more about your car's air conditioning, check out the next page.


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  • DriveWire. "ACC Cabin Filter Information." 2010. (Nov. 29, 2010)
  • Evans, Scott. "Refreshing: 2011 Infiniti M to Use Forest Air System to Freshen Interior Air." Motor Trend. Oct. 22, 2009. (Nov. 28, 2010)
  • Gerba, Charles P. and Sheri L. Maxwell. "Germs in Your Car Driving You Crazy?" Healthy House Institute. Dec. 7, 2009 (Nov. 29, 2010)
  • House of Japan.quot;Toyota Camry 2011." Sept. 14, 2010. (Dec. 8, 2010)
  • Infiniti. "All-new 2011 Infiniti M to offer innovative Forest Air system." Oct. 27, 2009. (Nov. 29, 2010)
  • Sharp. "Sharp's Plasmacluster technology: Positive and Negative Ions Purify the Air." Sep. 14, 2010. (Nov. 28, 2010)
  • U.S. Department of Energy. "Specification for HEPA filters used by DOE Contractors." January 1997. (Dec. 2, 2010)
  • Volvo. "A Volvo car ride can ease allergies." April 29, 2010. (Dec. 1, 2010)