The Health Impacts of Rush Hour Pollution

While your Facebook friends the past couple of weeks have been littering your feed with the shocking news that benzene in your car’s air conditioning is harmful – a claim, mind you, Snopes.com has debunked again and again since 2009 – those of us who sit in our cars during maddening rush hour commutes may have other worries besides distracted drivers and rising blood pressure.

A recent study published in the journal Atmospheric Environment suggests that the indoor pollution within our cars’ interiors may be much worse than previously believed.

Roby Greenwald, an assistant professor at Georgia State University, built a device designed to intake air at a rate akin to human lungs in order to measure indoor levels of air pollutants. The contraption was then fastened to passenger seats of over 30 cars, each of which completed at least 60 various rush hour commutes across metropolitan Atlanta. Whether commuters traveled along congested interstate highways or navigated through city streets to reach the city’s downtown, the eight researchers who worked together on this study found exposure to pollutants was higher than what has been assumed in previous studies.

In fact, estimates of particulate matter, or PM 2.5 – the microscopic particles that public health experts say can cause considerable damage to respiratory and circulation systems – was often twice as high as measurements from conventional traffic pollution sensors installed alongside roadways.

Several factors could explain these high levels of PM 2.5. Previous studies have shown that the composition of exhaust pollutants can change quickly once discharged from a vehicle. The intensity of pollutants on roadways can vary by the type of year and time of day. The bottom line is yes, the assumption that there are more pollutants surrounding us on the roadways during rush hour is true – but it is evident that beyond emissions, one of the larger problems is this pesky particulate matter. Various global health organizations have concluded that PM 2.5 can trigger various ailments such as heart disease, asthma and other respiratory diseases.

So what does this mean for the average John or Jane commuter?

In an interview discussing their research with Phys.org, the one of the study’s authors suggested these air pollution levels reflect the failures of urban planning. Another researcher chimed in, “Commuters should seriously be rethinking their driving habits."

Just what such a rethink should entail is a huge question for which city planners have limited answers. Despite some big-ticket public transportation projects on the drawing board, the evidence suggests more cities are cutting back on such systems as they see ridesharing companies such as Uber and Lyft picking up that slack.

And this spike in ridesharing throughout many cities, with San Francisco a prime example, indicates that traffic, and therefore emissions, will only become worse in the coming years. San Francisco’s civic leadership and citizens pride themselves on being one of the most “green” cities in the U.S. But residents and local officials have become more frustrated by gridlock on city streets; and a report this year suggested those two companies alone account for at least 20 percent of the city’s traffic. The result could be that money not spent on improved bus and rail systems will be spent on illnesses – while companies lose out because of lost productivity.

So even in sustainable San Francisco, more traffic means more pollution, and of course, more exposure to that particulate matter, one of the more serious long-term health threats to urban residents. But despite the return of citizens and companies to cities, public transportation systems either lack funds or political will. Furthermore, residents of these growing “smart cities” appreciate the semi-autonomy ridesharing offers them – after all, ridesharing is less crowded and more comfortable than a bus or train, and someone else is doing the driving. We will have to see a surge in air pollution-related illnesses before citizens and elected officials become serious about embracing public transport at a much wider scale.

Image credit: Gregor Smith/Flickr