As Americans, most of us spend a lot of time in our personal vehicles—sometimes hours every day. Sitting in traffic, driving on dusty roads, hauling loads and sometimes spilling food on seats and floors can introduce air pollution into your car that may affect your health as well as your enjoyment of the ride.

Sources of Pollution in the Car

The air that is circulating inside the cabin of your vehicle may include pollutants from three different types of sources: the outdoor air, the vehicle itself, and the occupants.

woman in car

Much of the air pollution in your car enters from the outside as you travel, through open windows and air vents. Gasoline and diesel exhaust fumes contain a number of dangerous pollutants, including particulate mattervolatile organic compounds (VOCs), nitrogen oxides and carbon monoxide. Exposure to traffic emissions on busy roadways with heavy truck traffic is a known health hazard, especially for people with respiratory problems and heart disease.

Cars and trucks are assembled from hundreds of different materials, including plastics, fibers, adhesives, paints and lubricants. Many of these products release VOCs into the cabin air as the car ages, including irritant chemicals and known carcinogens such as benzene and formaldehyde. Although the off-gassing of these compounds is highest when the vehicle is new – that “new car smell” – it persists for several years, and is most noticeable on hot days.

Gasoline fumes, which are another source of hazardous VOCs, can get into the cabin during refueling.

Moisture problems from leaks or floods can result the growth of mold in a car’s HVAC system and interior, which can trigger allergic reactions and asthma in sensitive individuals.

We don’t often think of ourselves as a source of indoor air pollution, but many things we bring into a vehicle, our behaviors, and even our breath can result in a pollution problem in a closed environment like a car cabin.  Household products frequently contain chemicals that become even more dangerous in enclosed environments.  Scented air fresheners and personal care products such as cosmetics and deodorants release VOCs. Food waste, papers and other clutter can gather dust and may harbor mold, bacteria and pests.

Secondhand smoke – including the exhaust from an e-cigarette - contains hundreds of chemicals known to be toxic or carcinogenic, including formaldehyde, benzene, vinyl chloride, arsenic ammonia and hydrogen cyanide, and can cause or make worse a wide range of damaging health effects in children and adults, including lung cancer, respiratory infections and asthma.

If you are driving with several passengers in a closed-up car for an extended period of time, the level of carbon dioxide you exhale can build up enough that it may impair your attention and make you drowsy.

man with filters

Tips to Improve Cabin Air Quality

Fortunately, there are some things you can do to reduce the sources of pollution in your vehicle:

If you have some flexibility, you can reduce the traffic-related emissions getting into your car by choosing less crowded routes and travelling at less congested times. Keep a safe distance from the vehicles in front of you, when driving and at traffic stops. You might also consider closing car windows and recirculating cabin air when stuck in traffic or at a stop light. When traffic is lighter and moving freely you can then open up to allow the fresher air to circulate.

You can reduce the dust and other indoor air contaminants with some clutter control and regular cleaning. No chemical sprays or air fresheners are needed. Wipe down surfaces, including door panels, console and dashboard with a damp cloth, and vacuum upholstery and carpeted floor and mats regularly. Clean up spills right away to prevent mold growth. Check the weather-stripping of the doors and windows for a proper seal, and address any leaks promptly. And of course, don’t smoke or vape in the car.

The majority of vehicles on the road today are equipped with a cabin air filter that is intended to protect the occupants from harmful pollutants. The cabin air filter is part of the ventilation system, and is different from the more familiar engine air filter found under the hood. Like the air filters in a home HVAC system, cabin air filters need to be replaced regularly to work effectively. Most manufacturers recommend changing the filter every 15,000 miles or so – check your owner’s manual for specifics. If you notice a musty odor or a drop in air circulation when you turn on the air conditioner that may be an indication that your filter needs to be replaced.

Page last updated: August 30, 2023

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