Recent monitoring conducted by air quality researchers at King's College London and the UK's Environmental Audit Committee (EAC) provides further evidence that "in-car" pollution can be many times higher than exposures for pedestrians and cyclists travelling the same busy route.
The BBC reports that British members of parliament on the EAC were fitted with air pollution monitors to test London levels for themselves. Travelling by taxi in rush hour traffic through central London, on a hot day with the windows open, the MPs' monitors recorded pollution levels six times higher than those recorded when walking.
A car in city traffic takes in pollution from the exhaust of vehicles in front of it, which then tends to get trapped inside; pollutants are diluted somewhat for pedestrians and cyclists, who have benefit of better airflow. Pollution levels also tend to be highest at the centre of a road, and lower at the verges.
In-car air quality is further reduced by the plastic interior off-gassing toxic compounds (that "new car smell"), as well as cigarette-smoking by passengers.
Read: How does pollution affect people who exercise outdoors?
Tips to lower your pollution exposure
Whatever your mode of transport, these tips will help reduce your exposure to urban pollutants:
- Avoid rush hour: bumper-to-bumper traffic produces the worst carbon emissions and the worst pollutant exposures.
- Avoid routes with busy traffic: discover some of the quieter, and often prettier, alternative routes.
- Pedestrians and cyclists can considerably reduce their pollution exposure by using walkways and cycle lanes, and cutting across parks and squares instead of using pavements directly adjacent to traffic.
- Setting your car ventilation to “recirculate” helps reduce exposure to air pollution.
- Driving with the windows open raises in-vehicle pollutant concentrations (and adds drag on the vehicle at higher speeds), but keeping windows closed for over half an hour with several passengers raises carbon dioxide levels inside (from exhaling). To prevent this CO2 buildup, outside air should be pulled in every 10-15 minutes for 1-2 minutes.
- The air is generally cleaner after a rainstorm or a blustery day.
- If walking and cycling's not for you, consider public transport: pollution levels are lower in buses than in cars, and even less in trains. (Underground railways tend to trap pollutants however).
Keep your car cool
Detox your garage
Car-pooling makes a comeback
BBC (September 2014). UK air pollution fuels official concern
Image of car exhaust: Shutterstock