Sheer proximity to tailpipes is one reason why cyclists have a high exposure to the tiny particle pollutants, which are emitted by vehicles along with thousands of other chemicals. Diesel buses and trucks are among the worst offenders.
"The closer you are to the source of the fresh exhaust, the worse it is," said Patrick Ryan, an environmental epidemiologist at the University of Cincinnati, who studies the health effects of traffic-related pollution.
Near the tailpipe, these particles are small enough to lodge deep in the lungs, triggering heart attacks and hospitalizations from lung diseases such as asthma. Tiny particles can also cross the blood-brain barrier, potentially harming the nervous system. Farther away from the tailpipe, these particles clump together, growing too large to lodge deeply, Ryan said.
That's why even a small separation from cars, created by physical barriers to traffic – something that's missing for most of 8th Avenue – is important for cyclists.
Two white stripes of paint, with a few feet of cycling space between them, is all that is reserved for bikers on this crowded street. Trucks commonly idle on the bike lane. Heavy traffic creates a wind tunnel that traps pollution on the road, according to a study by the California Air Resources Board.
A 2010 study of cyclists in the Netherlands showed that hard-pedaling, deep-breathing cyclists on busy roads inhale more of this dirty air. In many cases, they also spend more time exposed to it compared to someone driving the same distance.
"Those things add up and they give cyclists that cycle in traffic a high exposure," Brauer said.
But whether that exposure ups a cyclist's risk for heart or breathing problems has been less well established. One small study of Netherlands cyclists found a weak link between exposure to ultrafine particles and soot and airway inflammation.
The new study of Canadian cyclists does not mean that people should lock up their bikes and hop back into the driver's seat, said Brauer. Another study has shown that drivers have higher respiratory problems than cyclists because of their higher exposure to volatile organic chemicals in vehicle exhaust.
"In stop-and-go traffic, [drivers] have more exposure than a cyclist who stays 15 feet or more from the tailpipes," said Rebecca Serna, executive director of the Atlanta Bicycle Coalition, a cycling advocacy group.
The health benefits of cycling far outweigh the risks from air pollution and traffic collisions relative to car driving, according to one estimate by researchers in the Netherlands, where cycling is king. Taking cars off the road also helps reduce greenhouse gas emissions and traffic accidents.
"In general, you're better off cycling than not," Brauer said. "The physical activity benefits outweigh negative impacts. But you'd like there to be no impacts."
Exposure to dirty air adds to the perception problem that cycling is unsafe, said C.H. Christine Bae, an urban planner at the University of Washington in Seattle, who specializes in how bike facilities affect air pollution exposure.
The Canadian study authors have a simple solution. Avoid busy streets.
"When possible it may be prudent to select cycling routes that reduce exposure to traffic and/or to avoid cycling outdoors or exercise indoors on days with elevated air pollution levels," the research team wrote.
Others agree.
"Our recommendations to cyclists would be to avoid busy as streets as much as possible," said Dimitri Stanich, a spokesman for California's Air Resources Board.
Of course, cyclists might want to avoid busy streets for a number of reasons – fewer distracted drivers being one. But the busiest streets also have the dirtiest air, with ultrafine particle and soot exposure highest on busy roads, according to a recent study.
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7 Comments
Add CommentTwo paragraphs of this text have been duplicated.
Reply | Report Abuse | Link to thisI bike to work about 99% of the time and I try to run errands on my bike as much as I can. It always irks me when someone passes me driving a diesel pickup or a huge SUV on a suburban road, spewing out much more pollution that they have to.
Reply | Report Abuse | Link to thisI mean, I know that some people MIGHT need to tow something once a year or they have 5 kids or whatever, but when I see 1 person and zero cargo in a vehicle that looks like it has never been off road in its existence, I kind of wonder if that person even TRULY evaluated their REAL needs when buying that vehicle. Really, and this might sound smug, but why do I have to choke down all that extra pollution so THEY can have a false sense of security and an ego boost from their land yacht? What’s so hard about buying a sensible, fuel efficient passenger car for 99% of your driving and renting the pickup for the one or two times a year you actually use its capabilities?
The IC engine will soon be history. Never buy a new car.
Reply | Report Abuse | Link to thisYou miscounted: 4 paragraphs (7, 8, 9, & 10) are duplicated (11, 12, 13, & 14).
Reply | Report Abuse | Link to this"I mean, I know that some people MIGHT need to tow something once a year or they have 5 kids or whatever, but when I see 1 person and zero cargo in a vehicle that looks like it has never been off road in its existence, I kind of wonder if that person even TRULY evaluated their REAL needs when buying that vehicle. Really, and this might sound smug, but why do I have to choke down all that extra pollution so THEY can have a false sense of security and an ego boost from their land yacht? Whats so hard about buying a sensible, fuel efficient passenger car for 99% of your driving and renting the pickup for the one or two times a year you actually use its capabilities?"
Reply | Report Abuse | Link to thisDitto. It always amazes me, the level of irrationality associated with so much of our purchasing decisions, most of which seem aimed at social validation rather than at actual satisfaction of our needs. That's just putting too much power on other people's hands so that we can feel the approval of the herd.
Returning to the article, as a bicycle commuter, I reduce the problem by choosing my hours carefully: the early bird avoids rush hour.
"the early bird avoids rush hour."
Reply | Report Abuse | Link to thisThe late bird does too.
Is it not true for anyone walking, or basically living, in our cities that pollution of all sorts will have an effect of their lungs? The concentration, due to high volumes of traffic, will be according to exposure. Any one working outside, from street vendors to police, etc. is exposed not just bicyclists. Improvements in car technologies is reducing pollution. But it is in our hands, or feet, how much we pollute. We all seem to be driving in a continuous high state of anxiety about "time" and seem to be speeding to all our destinations. It has been estimated that on average we all decrease efficiency, or miles per gallon, in the range of 30%. Speeding, idling, looking for that extra close parking slot, etc. basically throws about 1/3 of our gasoline purchase out the window! No wonder oil companies enjoy 8 to 10 billion in profits each quarter!! Yet,in view of these facts, we continue our wasteful driving habits much like addicts that continue behavior they know is bad for them. It has been said that you cannot manage what you do not measure. Have you measured your driving efficiency? Recent studies have confirmed that even with technology in the vehicle that can tell drivers how efficient, or not, they are driving, drivers will not change their habits. Average extra cost? About $400 each year. More for those who drive extra large vehicles.
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