How Polluted Is Rush Hour?

A new study into levels of air pollution at rush hour has uncovered some rather disturbing results, for both those on the streets and behind the wheel. By placing a sophisticated air monitor inside the passenger seat of various cars at rush hour, researchers were able to discern that pollution levels were almost double those experienced at roadside.

The daily commute more dangerous than you think

In the wake of news earlier this year that levels of pollution on the London underground can be up to eight times as bad as those found on the city’s streets, you’d be forgiven for opting to take your car to work rather than commuting on the Tube.

However, new research from Atlanta, Georgia shows that driving might not be all that much more beneficial for your health. The first in-car experiment of its kind, the study measured levels of particulate matter inside a number of different cars at rush hour, uncovering some rather startling news.

A joint study between the Georgia Institute of Technology, Emory University and Duke University, the paper showed that pollution levels could be almost double inside the car than that detected by roadside sensors, thus highlighting the danger of driving.

Why the discrepancy?

It might seem logical to think that those outside on the city streets would be exposed to higher levels of pollution than drivers, since they move much more slowly and do not have a shell around them protecting them from the fumes.

However, the cars themselves can often trap contaminants inside, making it very difficult for polluted air to disperse once it has found its way in. With air conditioning systems sucking air from the atmosphere outside – often directly from the exhaust pipe of the car in front – the driver can become something of a sitting duck in his vehicle.

What’s more, the sunlight experienced outside a car can help to heat the road surface, which in turn produces an updraft that lifts the pollution higher, away from human lungs. Finally, sensor readings aren’t always accurate because the composition of air can change dramatically from just a few metres apart, meaning that the air inside is more constant (and more contaminated).

What’s to be done?

The UK government have regularly been taken to task by both the EU and environmental law group ClientEarth for their failure to improve air quality and reduce transport-related pollution, having already lost two court battles over the subject.

As a result, they are considering introducing a raft of air quality control measures, including ultra low emissions zones (ULEZs), reconfiguring traffic signal placements and replacing speed bumps with speed cushions in a bid to encourage smoother driving.

However, on an individual level, people may wish to tailor their driving habits to avoid rush hour – even if it means getting up for work an hour earlier and leaving an hour later. “We found that people are likely getting a double whammy of exposure in terms of health during rush-hour commutes,” explained Michael Bergin, one of the authors of the paper. “If these chemicals are as bad for people as many researchers believe, then commuters should seriously be rethinking their driving habits.”