Surprisingly, pollutant levels are often higher inside because cars take in emissions from surrounding vehicles and recirculate them. Studies have found that as much as half of the pollutants inside test cars come from the vehicles immediately ahead, especially if those vehicles are highly polluting, such as heavy-duty diesel trucks. Levels of some pollutants and toxic compounds can be as much as 10 times higher inside vehicles than alongside the road.
How to reduce in-car pollution
- When driving in traffic, keep a safe distance from vehicles ahead of you, especially diesel trucks or obviously polluting cars. Or pull over to let such vehicles get far ahead. Keep the windows closed when in traffic and the ventilation set to recirculate, especially in tunnels.
- When stopped at traffic lights, close your car windows, and try to keep some distance from the car in front of you.
- When driving in light or no traffic, keep windows open or at least cracked to let in fresh air.
- Properly maintain your car. A poorly maintained car is more likely to pollute the air inside it as well as the air around it.
- Choose less congested roads with fewer traffic lights, even if they take a little longer. Or try to avoid rush hour. The more traffic, the more pollutants.
- Drive in the carpool lane. Carpool lanes tend to have less traffic, so there’s less air pollution.
- Take public transportation. Not only will you avoid pollutants, you’ll also help reduce traffic congestion and emissions. Buses, however, can be very polluting—and the air inside them quite polluted.
- Don’t count on in-car air filtration systems. Some car dealers offer charcoal (carbon) filters on select new models. These may help reduce allergy symptoms from pollens, for instance, but they are not effective in removing fine particulates, volatile organic compounds, carbon monoxide, or other pollutants.
- If you have a new car, try to drive on less-busy roads so you can keep the windows open as much as possible for the first few months, when VOC levels are highest. Don’t park it in direct sunlight.
- Don’t use air fresheners or deodorizers in your car.
- Keep interiors clean. Pollutants in cars can combine with dust particles, which are then inhaled.
- On long drives with several people in the car, open the window for a minute or two every 10 minutes so carbon dioxide doesn’t build up.
- Don’t use chemical cleaners. Instead, use a damp micro-fiber rag to keep the interior clean. (Dust holds onto pollutants, such as VOCs.)
- Instead of an air freshener, if you want the air to smell fresh, open the windows in an unpolluted area. If that’s not possible, make a sachet of dried flower petals, or keep an open container of baking soda in the car where it won’t tip over. (You can sprinkle the baking soda under floor mats and on the carpet, vacuuming up any residue.)