More and more people are cycling to work in cities, yet air pollution remains a constant concern. Can the health benefits of cycling really outweigh the risks of inhaling pollutants? Scientists at Columbia University in the United States are using new devices to study the impact of vehicle exhaust on cyclists.
Does cycling in the city harm your health?
By: Aaron Sidder
Many cycling enthusiasts have experienced this: one minute you’re riding freely, the next you’re engulfed in a cloud of car exhaust. All you can do is pedal harder and steer away from the smoke. Nowadays, more and more studies show that inhaling such pollutants can cause both short-term and long-term health problems.
A team of researchers at Columbia University has employed a new generation of personal monitoring equipment to gain more detailed insights into how air pollution affects cyclists’ health.
This study, conducted jointly by the Mailman School of Public Health and the Lamont-Doherty Earth Observatory, aims to show how health and pollution data fluctuate on a minute-by-minute basis.
Researchers equipped volunteer cyclists with a tight-fitting vest that collects biometric information, a mesh vest housing an air pollution monitor, a positioning system synced with smartphone GPS software, and a blood pressure monitor. Together, these devices accurately map where a volunteer inhales pollutants and record their cardiopulmonary responses.
“We really want to quantify how cycling in congested urban environments affects the health of commuters,” says Darby Jack, an environmental health expert at Columbia and one of the masterminds behind the study.
Pollution Issues
Health officials estimate that in New York City alone, PM2.5 contributes to nearly 2,000 premature deaths and over 6,000 hospital visits each year. Children and the elderly are especially vulnerable, as are those with respiratory conditions like asthma and heart disease.
“Internal combustion engines produce particles that come out of tailpipes, and then we drive along sidewalks. It seems like we’re emitting this stuff right into our breathing zone,” says Arden Pope, a professor of economics and epidemiology at Brigham Young University (who was not involved in the Columbia study).
Once these particles—especially the fine ones—are emitted from exhaust pipes, they are inhaled and accumulate in the lungs. Most of these particles are black carbon, but vehicles also emit nitrogen oxides and polycyclic aromatic hydrocarbons.
Research shows that long-term exposure to these pollutants increases the risk of cardiopulmonary diseases, while short-term exposure can trigger heart problems.
Exercise exacerbates the issue. During physical activity, breathing increases, drawing more air—and more pollutants—into the lungs. For example, jogging can increase the amount of air entering the lungs by three to four times, and intense exercise even more. All this extra air brings more pollutants into the lungs.
This poses a dilemma for urban cyclists: how much exercise is enough to reap more benefits than harm?
It’s generally believed that the benefits of exercise outweigh the harms of air pollution, and recent research supports this “in the vast majority of cases.” For instance, in New York City, where the baseline PM2.5 levels are lower than the global average, a healthy person without cardiopulmonary issues would need to cycle for several hours a day before the negative effects of pollution outweigh the benefits of exercise. By then, you’d probably just be dealing with a sore bum from all that riding.
However, Jack argues that focusing solely on baseline levels is incomplete: “You’re completely underestimating what people are exposed to when they exercise in the city.” Pollution levels vary by location—they’re not static or evenly distributed. As we move through the city, our exposure changes based on where we are.
Epidemiologist Patrick Ryan of Cincinnati Children’s Hospital Medical Center explains: “Using a single PM2.5 value to represent an entire city doesn’t reflect true exposure. We know people are exposed to air pollutants throughout the day, and that really affects exposure levels.”
Moreover, exposure levels also vary based on your activity level. Cycling uphill behind a stinky garbage truck is a far cry from cruising effortlessly on a flat road.
Shifting Gears
As cycling grows in popularity (with over a million New Yorkers biking each month), health and safety are becoming top priorities for cycling advocates.
According to Paul Steely White, executive director of Transportation Alternatives in New York City, advocacy groups primarily focus on preventing crashes and injuries, but they also pay close attention to pollution data. He explains that safety and pollution trends are interconnected, and his organization takes this research seriously.
The study is currently in its trial phase, and Jack and his colleagues are focused on convincing themselves and their funders that health and pollution data can be collected in real time simultaneously.
Around 30 cyclists—both men and women from all over New York City—are currently participating in the study. However, the team hopes to expand the cyclist group to several hundred within the next few years. Eventually, Jack hopes the data can be integrated with smartphones to help cyclists optimize their routes based on pollution levels.
For now, the research team is refining measurement methods and calibrating equipment to better document the “cycling life” in New York City.