During the hot summer months, contaminants, such as pollen, dust, mold spores and smog, can easily enter a vehicle's passenger compartment through the air conditioning, heating and ventilation systems, making the air in the car six times dirtier than the air outside, cautions the Car Care Council.

Motorists can protect themselves and their passengers from these containments by replacing the vehicle's cabin air filter annually or more often in areas with heavy containments, or whenever heating or cooling efficiency is reduced. Cabin air filters clean the incoming air and remove allergens -- especially beneficial to people who suffer from allergies.

If your vehicle is model year 2000 or newer, there's a good chance it is equipped with a cabin air filter.

"There are about 30 million vehicles in North America that currently have cabin air filters," said Rich White, executive director of the Car Care Council. "However, most people have never heard of a cabin air filter or don't know if their vehicle is equipped with one. Vehicle owners should refer to their owners' manuals for this information."

If the cabin air filter is not replaced, it can cause musty odors in the vehicle, and over time, the heater and air conditioner may become damaged by corrosion. A dirty or clogged cabin air filter can also cause containments to become so concentrated in the cabin that passengers actually breathe in more fumes and particles when riding in the car compared to walking down the street.

As part of the "Be Car Care Aware" education campaign, the Car Care Council is offering a free service interval schedule to help take the guesswork out of what vehicle systems need to be routinely inspected and when service or repair should be performed. The schedule can be printed for free from the Car Care Council's Web site at www.carcare.org.