While sitting in your car during the daily commute may seem fairly harmless, drivers are exposed to huge amounts of air pollution while in their vehicle.
But scientists believe they may have found a simple way to reduce this in-car pollution.
In a new study, researchers discovered that using air conditioning can reduce the amount of pollutants in the car by up to 34 per cent.
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Researchers from Washington University in St Louis discovered that a simple shift in driving habits can help to reduce in-car pollution while out on the road.
Dr Anna Leavey, who led the study, said: ‘We know that traffic generates a lot of pollution, and therefore it’s the time when you’re travelling in traffic that you can have a disproportionately high amount of your daily exposure to many harmful pollutants.
‘What we wanted to see was: When and where are our highest exposures occurring, and how should one be driving to mitigate the risk?’
The researchers used portable instruments and sensors to monitor and measure the pollutant levels of a car’s indoor cabin air and the air directly outside the car during their own daily commutes.
Nathan Reed, who also worked on the study, said: ‘As aerosol scientists, we had access to state-of-the-art air monitoring equipment.
‘Once we began measuring inside and outside of the car, and started getting numbers back, we were able to confirm our hypothesis that by controlling our car’s ventilation we could mitigate some pollutant risk.’
The cars were fitted with dash-cams, allowing the researchers to identify a given pollutant concentration each time they were stuck behind a bus or truck, in traffic on a freeway, stopped at a red light, or driving past restaurants or construction sites.
They also used a range of ventilation settings inside the car – windows open, windows closed, fan on, and air conditioning on.
After a month testing the pollution levels, the researchers discovered that using air conditioning reduced the pollutants in the car by 20-34 per cent, depending on the outdoor concentrations.
Mr Reed said: ‘We found a significant difference between running the fan versus running the AC.
‘The AC is pulling outside air, running through the same filter with the same ventilation path as the fan.
‘But there’s one difference: when the AC is operating, you have a cold evaporator that is cooling the air as it passes.
‘This cold surface attracts the pollutant particles, and they deposit there, as opposed to diffusing it into the air you’re breathing.’
This particle deposition was found to be most effective when exposure was elevated, such as when the car was behind a bus or truck.
Keeping the windows closed also offered a protective boost of anywhere from eight to 44 per cent, after all factors were taken into account.
Dr Leavy added: ‘The vehicle cabin can be viewed as a buffer, protecting us from the outside air.
‘While driving with your air conditioning on and windows closed is the most protective thing that you can do, running the AC can decrease your fuel economy.
‘That’s why adopting a dynamic behavior modification approach is recommended, in which the AC or closed windows are used when following a highly polluting vehicle, or on the freeway which tends to be more highly polluted.
‘Once you have left the polluted environment, we recommend opening your windows to remove any pollutant build-up from your car.’