Testing by MPs reveals worst air pollution is inside cars

Where do you find London's worst air quality? It's not on the pavements where pollution monitors are positioned, or at the road edges where cyclists ride. Instead, it's, inside cars themselves, according to a new study.

The Sunday Times reports that researchers at King’s College London used five MPs from the Government's Environmental Audit Committee (EAC) as guinea pigs in a study of London air pollution.

The MPs were set up with devices that measured airborne pollution and used GPS to record the location.

“Travelling in vehicles gave the greatest average exposure,” said Dr Ben Barratt, a senior air quality scientist at King’s who oversaw the research. “Among the worst was when the MPs got a taxi across London.”

The monitors measured the amount of microscopic carbon particles - produced largely by diesel engines - that the MPs inhaled. Inside taxis, they were found to have inhaled up to 50 million particles per breath.

Walking around Whitehall and Oxford Street, they inhaled 6-7 million particles per breath. At their destination, London's City Hall, levels fell to 3 million particles per breath.

The MPs — Joan Walley, Labour chairwoman of the EAC, Alan Whitehead, Labour, and Matthew Offord, a Conservative — will get the chance to ask London mayor Boris Johnson to explain that discrepancy when he gives evidence to the committee on Wednesday, where he will be asked to account for London's constant breaching of EU air quality standards. (Two other MPs, Mike Kane and Caroline Nokes, also carried the monitors.)

Johnson is set to announce a new initiative this week in which Londoners will be asked to work from home and reduce car use when air pollution levels are high. Instead, they will be asked to use bikes, trains and buses if they have to travel.

But London is not the only city with air pollution problems.

Whalley's monitor peaked at 80 million particles per breath during a taxi ride around her Stoke-on-Trent North constituency. Barrett believes that the problem is that pollution from one car is sucked in by another.

“Vehicles close together suck in each other’s emissions,” he said.

“The air intakes are in the engine compartment close to road level, so they pick up the fumes emitted by the vehicle in front of them. Open windows are another route.”

A review published in the journal Science of the Total Environment, which compared people’s exposure to particulate pollution during different types of commuting such as cycling, driving, trains and buses, supports Barrett's findings.

After examining data from several European and British cities, the authors concluded: “Compared with other transport methods, travelling by car has been shown to involve exposure both to higher particulate matter and to black carbon, even compared with cycling.”

Research has shown that levels of all kinds of air pollutants are at their highest in the middle of a road and in the two or three feet above the road surface. They fall off in the few yards to the kerb — and that's where both pedestrians and pollution monitors are found.

Commenting on the research, Walley said: “During the smog earlier this year, the Mayor said that the quality of the air on his cycle into City Hall seemed ‘perfectly fine’ to him. Yet when we monitored air quality outside City Hall, the levels of carcinogenic particulate pollution were more than three times lower there than what shoppers were being exposed to on Oxford St.”

“There is mounting evidence that air pollution can damage the development of children as well as shortening the life of those with underlying health conditions. We will be asking the Mayor whether he thinks it is acceptable that citizens in our capital city will have to wait until the 2020s before they can breathe safely. Our inquiry has raised concerns about whether the Government and Local Authorities are doing enough to get the most polluting vehicles off the road or to encourage pollution-free forms of inner-city transport such as cycling.”

“Our monitoring experiment also showed that people in vehicles were far more exposed to air pollution than they would be walking along the street, because it builds up in the cars, buses and taxis when they are stuck in the middle of traffic. Car makers test tail pipe emissions but this raises a question about whether manufacturers should also be considering air quality inside vehicles.”