Car air pollution is a silent and invisible problem. We tend to think that inside our cars we are safe from most things that can hurt us, but that is far from the truth — especially where air quality is concerned. We can see the air pollution outside, but inside it’s invisible and thus not on our minds.
Many people spend several hours per day in cars, breathing air that is often more polluted than the air outside of the vehicle. In-car air pollution is not measured by government monitoring stations, and there are no car air pollution standards that automakers must meet. Even when local air quality testing reports are “green”, the air you are breathing in your car may be very “red” — up to ten times as polluted as the air on the other side of your windshield.
Measuring Concentrations of Selected Air Pollutants Inside California Vehicles is a 1998 study comparing air pollutants measured 20 feet from roadways and inside of different types of passing vehicles was conducted for the Research Division of the California Air Resources Board (CARB), a department of that state’s Environmental Protection Agency. The researchers drove on freeways, arterial roads, and rural roads under a variety of conditions in Los Angeles and Sacramento, and measured pollutant levels in a 1991 Chevrolet Caprice, a 1997 Ford Taurus, a 1997 Ford Explorer, and a school bus.
Gasoline and diesel engine exhaust emissions are the main ingredients of car air pollution. These emissions include volatile organic compounds (VOCs) such as benzene, toluene, and formaldehyde (all known carcinogens); carbon monoxide (which reduces the blood’s ability to carry oxygen to all cells of the body); and particulate matter (which clogs lungs and has been shown to shorten life spans). Sulphur was more highly concentrated in car air pollution that in ambient air. Concentrations of metals such as chromium and lead were similar inside and outside of cars.
Driving with windows rolled up does not help. The air conditioning systems of most cars do virtually nothing to filter out car air pollution. Indeed, the air intake vents of most passenger vehicles are located near the ground, approximately on the same level with pollution-emitting exhaust pipes.
There are things one can do to minimize exposure to car air pollution. Obviously, drive as little as possible. Avoid peak traffic times and congested roads. Don’t drive behind heavy car air pollution emitters such as diesel-burning trucks, buses, and cars; older model vehicles; sport utility vehicles; and poorly maintained, visibly “smoking” vehicles. Don’t tailgate. Open windows for cleaner air. Avoid surrounding your car with other polluting vehicles by driving in the outer- or inner-most lanes. Carpool — the study found that car air pollution was significantly less in vehicles driven in less-used High Occupancy Vehicle (HOV) lanes.
Car air purifiers range from worse than useless to questionably effective.
Scent-impregnated foam “hangers” that dangle from one’s rear-view mirror do not remove car air pollution; they only contribute allergens to the air. Avoid scent packets in filtration and ionizing appliances for the same reason.
Filtration systems that mount on door panels, headrests, and other areas do not filter all air that enters via intake ports. They only filter what passes by them. A power cord that typically plugs into a car’s cigarette lighter port may pose a tangling hazard. Battery-operated filters lack sufficient power to pull in air from more than a couple inches away from the filter’s intake port.
Air ionizers can significantly reduce in-car air pollution. Ionic air purifiers generate electrically charged air molecules that “stick” to car air pollution molecules and then stick to surfaces, thus removing pollutants from the air. Ionizers are popular because they are silent. But that means they have no fans to spread charged molecules throughout the passenger compartment. So ionizers must be mounted as close to passenger compartment air inlets as possible. Mounting an ionizer near a fan-driven air inlet helps spread the pollutant-trapping charged air molecules throughout the passenger compartment. Be aware that air ionizers may interfere with radio reception, radar detectors, and other electronic equipment. Interior surfaces should be cleaned regularly to remove car air pollution that sticks to them.
One air purifier in the front passenger area may not be enough. Ventilation and air circulation are poorest in the rear passenger area of all vehicles. This is where passengers who are most vulnerable to car air pollution often ride: infants, children, the infirm and the elderly. If your car transports such at-risk persons, additional air purifiers are a vital investment.
Car air pollution is an underestimated air quality concern. Besides cleaning up your own car’s interior air, you should lobby your government representatives, the EPA, and automakers to establish standards for car air pollution and goals for reducing them to zero.