June 5, 2015

It’s pretty much taken for granted that riding a bike is good for you.

Studies have shown that biking not only benefits your physical health, it’s good for your mental health too. But cycling also carries some potential health risks—and not just the ones that come from a car door opening into your bike lane or riding without a helmet. Air pollution can also be a big problem for cyclists when they share the road with motorists.

“I’ve had to get off my bike because I’ve been coughing so hard, either getting behind a big truck or something like that,” says Adam Haller, a bike commuter who also works at Thick Bikes on Pittsburgh’s South Side. “Sometimes I’ll notice, if I’ve been in a really heavy traffic ride, I can almost feel a film on my skin. And the smog doesn’t feel good at all.”

Pittsburgh cyclists may have it especially bad. Air pollution in Pittsburgh is a serious public health issue. In fact, the city still consistently ranks among the 10 worst cities in America when it comes to air quality. A lot of that pollution, just like in other metro areas, comes from cars and trucks. And when cyclists share the road, they’re also sharing in all that car exhaust, which contains all kind of things that can be harmful to your heart and lungs.

Researchers are now starting to get a better idea of just how all that stuff moves around—or doesn't—in the city. For the last couple of years, Dr. Albert Presto, a mechanical engineer with Carnegie Mellon’s Center for Atmospheric Particle Studies, has tracked air pollution in the Pittsburgh area using a tricked-out cargo van that functions as a mobile lab.

“Inside of it, we have different monitors for every pollutant that we’re interested in,” Presto says. “And to get our sample to each of those instruments, we have a tube that sticks out of the roof, and we suck air in through that tube to all of the different instruments.”

Presto and his grad students drove this cargo van all over the city for a couple of years. And now, they’ve put all the data they’ve collected into a big color-coded map that gives a more detailed look at the Pittsburgh area’s air pollution. It’s sort of like a weather radar map but for air quality. Red spots on the map indicate bad air; blue is better air quality.

Some of what you see is what you’d expect. Industrial plants and major roadways are big red splotches on the map. But there’s also a lot of red along the rivers—partly because the river valleys tend to trap pollution. And this has huge implications for cyclists in Pittsburgh—because most of the city’s major bike trails run right along the rivers.

“A lot of people cycle along the trail network near the rivers. So there’s definitely opportunity that maybe you are increasing your exposure to, especially, traffic-related pollution,” Presto says.

Even so, you’re probably still better off biking than not. Most of the research out there shows that exercise, even in polluted areas like cities, is still a net benefit to your health. And one of the big payoffs of Presto’s maps is that you can actually use them to plan bikes routes with better air quality.