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How cycling can be dangerous to your health

MinnPost photo by Steve Berg
Bicyclists are making a personal effort to reduce carbon emissions and pare our reliance on fossil fuel.

As a kid, I loved to bike. On my two-wheeler, I could zoom far beyond my neighborhood to deliciously unsavory places where my parents forbade me to go. When as an adult I moved to Manhattan, where driving a private car is problematic, I again took to the bike as a convenient mode of transportation free of subway and bus schedules.

But several incidents over the years got me off the streets. First, there was the taxi driver who swerved in front of me as I toiled up Manhattan’s 6th Avenue during my fifth month of pregnancy. “Ya know, lady, ya can get knocked down too!” he bellowed out his window. Then there was the time that another cyclist veered right up to me in Central Park and pinched my bottom, really hard. I gave chase but drove over a pothole, toppled and wound up with a bad case of road rash.

All that made me realize that bikers, especially klutzy ones like myself, are out there, unprotected — from the elements, from drivers and from other bicyclists who sometimes, in their war against the wind, the snow and the traffic, take on the ethos of a Mad Max. 

You’ve got to say, however, that cyclists are valiant. After all, they are making a personal effort to reduce carbon emissions and pare our reliance on fossil fuel. Plus, they develop awesomely muscled thighs and rears that add to our enjoyment of the cityscape.

Their brains are bulked up, too. Danish scientists testing how well schoolchildren perform when they eat a solid breakfast and lunch recently reported that how the kids got to school was more significant than what they ate. Those who biked or walked performed better than those who rode in cars or took public transportation. Niels Egelund, a co-author of the study, said: “As a third-grade pupil, if you exercise and bike to school, your ability to concentrate increases to the equivalent of someone half a year further in their studies.”

Brain power

Bicycling seems to work well on aging brains, too. A UCLA study found that people aged 65 to 69 who were most active (via walking, swimming and biking, of course) had 5 percent more gray matter than those who were least active. Gray matter, aka the cerebral cortex, processes much of the information we use, and its shrinkage contributes to senile dementia.

But biking is still dangerous. For starters, there are traffic accidents. In 2011, the last year for which statistics have been reported, fatalities among bicyclists around the country rose by 8.7 percent over the previous year to 677. Some 48,000 cyclists were injured. That’s 4,000 fewer than the previous year, but still a massive number.

Minnesota has performed much better than the nation as a whole. According to MNDOT, while bike riding is up, fatalities in the state have dropped. In 2011, four bicyclists were killed, the lowest number since 2007. Still, from 2008 to 2010, 836 were injured and 32 died on Minnesota roads. 

But bicyclists, as it turns out, face another peril: pollution. New research has found that bicycle commuters inhale twice the amount of black carbon particles as pedestrians. Inhalation of such gunk (aka soot) is associated with reduced lung function and even heart attacks. 

The researchers, led by Professor Jonathan Grigg from Barts and the London School of Medicine, compared carbon levels in the lungs of five healthy bicycle commuters those of five healthy pedestrian commuters. The bicyclists had 2.3 times more of the bad stuff in their lungs. Presumably, the cyclists’ heavy breathing — all that good aerobic stuff — is responsible for the increased presence of black carbon.

More bad news

There was even more distressing news from scientists at the University of California in San Diego. The researchers gave smartphones with pollution sensors to 30 study participants and then analyzed data collected over a month. The people doing the most to reduce carbon emissions by cycling or riding the bus “experienced the highest levels of exposure to pollutants,” according to William Griswold, the lead investigator.

How could this possibly happen? Well, it turns out that pollution drifts around, rising and falling during the day, usually on heavily trafficked routes or intersections. So people who bike to work along a very busy route could be inhaling clouds of carbon monoxide and ozone. Being sealed inside a car along the same road would lessen exposure. Bus riders, who are also trying to reduce their carbon footprints, inhale volumes of exhaust by standing at bus shelters.

Fortunately, bikers can vastly minimize their exposure by shifting off a busy route, sometimes only a block away. And, apparently, there are apps that can be downloaded onto a phone that will give cyclists real time pollution information so they can stay away from the worst parts of town. Scientists conducting the study suggest that bus riders avoid standing in a shelter near the back of the bus, which is where air quality is the worst.

There’s probably no quick fix for all those bicycle accidents. Statisticians say that the most common reason for bike crashes is failure to yield right of way. Cyclists often ignore stop signs and lights. For their part, drivers don’t pay attention to bikers. Or don’t even see them — until it’s too late.

Worry not. Two inventors, Jonathan and Andrew Lansey, have developed a bike horn that sounds just like a car. They’ve already raised money to manufacture what they call “Loud Bicycle” on Kickstarter, where you can hear what it sounds like — it should stop any motorist cold — and even place an order.

Comments (19)

  1. Submitted by Benjamin Riggs on 01/08/2013 - 12:58 pm.

    Numerical fear mongering

    I find it rather unfortunate that you post bicycle-related injury statistics in an effort to show how dangerous cycling is without giving any context for those numbers. Sure, 48,000 cycling-related injuries seems high, but that’s on the order of the 32,367 motor vehicle related *deaths* nation-wide in 2011, which vastly dwarfs the 677 cycling deaths.

    In Minnesota alone, you seem keen to point out 36 cyclists have died from 2008-2011, but, again, fail to include any comparisons: ten times more drivers died in 2011 than cyclists in the previous four years. (Furthermore, cycling levels have dramatically risen since 2007 and numerous studies show a very strong link between increasing levels of cyclists and rapidly declining levels of cycling-related accidents. To a cynical mind, it may look like you’re cherry-picking your numbers to support your claim.)

    One might argue that drastically higher numbers of motor-vehicle deaths are to be expected because so many more drive then bike, and go on to cite statistics showing bicycles are more dangerous than cars per vehicle mile traveled (VMT). While factually correct, these statistics are misleading simply because cars travel faster then bicycles and, thus, cover more miles in a given time-frame.

    When statistics for accidents are analyzed on either the basis of time spent traveling or per individual trip, it turns out bicycles are as safe or safer than cars.

    • Submitted by Rachel Kahler on 01/11/2013 - 12:56 pm.

      Out of curiosity

      While I get your point, how many more drivers are there than cyclists? Is a cyclists life more at risk as a group than a driver’s as a group? I honestly don’t know, and I’m not going to do the calculations. I don’t know that your concerns regarding miles traveled are relevant, either, as you can’t (as you note) directly compare a trip by a driver to a trip by a cyclist. I’m inclined to believe that the cherry picking may have little effect on the overall conclusion–especially those regarding inhalation of pollutants. I certainly am not inclined to believe your assertion that bicycles re as safe or safer than cars until someone can find a good way to directly compare them. I, personally, believe that many cyclists are insane for riding in the traffic as they do. Some of them are intentionally so, as a thumb to the nose at drivers that share their space. trust me, when I’m driving, I am extremely cautious around cyclists, but some of them probably have it coming if they get hit (no, not by me…hopefully).

      In the end, our streets are not exactly cycle friendly. More could and should be done about that. And I think this article provides more than enough reasons to do so.

  2. Submitted by Janne Flisrand on 01/08/2013 - 01:47 pm.

    Out of context

    All the perceived “dangers” listed here (accidents, air pollution) need more context. Reinforcing false perceptions of the dangers of riding a bike misinforms readers.

    How about accident data per trip? Or comparing bike and car injury data? How about doing it in a regional context? Bicycle accidents vary hugely by state, as well as by city. Minneapolis and St. Paul are some of the safest places to ride a bike.

    The “risks” of air pollution should also be offset by the health benefit of regular cardiovascular exercise. When this air pollution report first came out (the reports I found were from 2010), there was a lot of analysis of the NET benefit — the combined risk of pollution exposure PLUS the benefit of exercise. Those pretty consistently came out a couple years in favor of bicycling, showing that DESPITE the pollution, people who bike live longer.

    And, one pet peeve. I don’t ride my bike to “make a personal effort to reduce carbon emissions and pare your reliance on fossil fuel.” I ride it because it’s convenient, fast, and fun. I’m tired of being portrayed as some sort of holier-than-thou do-gooder. It’s simply the best way for me to get around.

  3. Submitted by Daniel Olson on 01/08/2013 - 02:07 pm.

    Biking is dangerous because of air quality?

    I see your point, but isn’t the real danger the activity that produces pollution in heavily populated areas? If emissions from cars, buses, or burning coal will be enivitably inhaled by everyone around, just more deeply by those getting exercise, does the problem really lie with those who dare exercise in urban areas? If we all protected ourselves by driving instead of biking or taking transit, wouldn’t the underlying problem just get worse?

    I think the real dangerous activities are those that emitt soot and other pollution in dense areas.

    Is it worse for your health to exercise in areas with poor air quality or not exercise at all?

    This past season I bike commuted from early March to late November. Since then, I’ve been riding the bus. In just over a month without biking, I’ve put on weight, get out of breath easier, and I miss showing up to work in the morning and home at night with a clear head and positive mood that comes from daily exercise.

    I really hope I don’t get run over by a truck on my bike, though. Maybe your next article could be about the danger of allowing 2000lb steel boxes barrell through dense areas populated by bikers and pedestrians.

    I suppose how we define a “dangerous activity” is determined by whether we are thinking just about our own safety or everyone else’s as well.

  4. Submitted by Ethan Fawley on 01/08/2013 - 02:47 pm.

    Health benefits vastly outweigh costs

    It is strange–and disappointing–that the personal health benefits of biking are mostly ignored in this article.

    A 2010 report called “Do The Health Benefits Of Cycling Outweigh The Risks?” concluded:
    “On average the estimated health benefits of cycling were substantially larger than the
    risks of cycling relative to car driving. For the society as a whole this can be even
    larger as there will be a reduction in air pollution emissions and eventually less traffic
    accidents. Policies stimulating cycling are likely to have net beneficial effects on
    public health especially if accompanied by suitable transport planning and safety

    I’m one of tens of thousands of Minnesotans who is much healthier today because I bike regularly. I weigh 10 pounds less than when I didn’t bike. My total doctor bills in the last four years are less than $600. That isn’t for nothing–it is in big part because I stay active through biking and other activities.

    All that is why nearly every health-related organization, business, hospital, doctor, etc. recommends biking.

    That isn’t to say that we shouldn’t make it safer, more attractive, and even better to bike. The points you’ve listed here are valid. But without context, it seems like you are cherry picking facts in a way that leaves out that biking is great–for your personal health among other things.

  5. Submitted by Amy Bergquist on 01/08/2013 - 03:02 pm.

    Bike corridors

    Benjamin makes some excellent points about how the article frames the data.

    I’ll add that bike corridors (Midtown Greenway, Cedar Lake Trail) likely reduce all of the risks identified in the article. There’s probably a big difference in traffic safety and exposure to pollution between biking two miles on Manhattan or in London and biking 1.5 miles on the Cedar Lake Trail + .5 miles in moderate traffic in downtown Minneapolis.

  6. Submitted by Eric Ferguson on 01/08/2013 - 03:19 pm.

    increasing accidents

    I would assume accidents and deaths would rise as bicycling increases. The fact Minneapolis and St. Paul are doing better despite more of a rise could be that drivers have gotten more accustomed to bikes. As I’ve seen drivers do much better about things like parking on bike lanes, I’ve suspected safety improvements might be due to drivers adjusting to more bicycles.

    It also stands to reason that if bicycling increased before infrastructure to enable bicycling, that would be the most dangerous time. We were one of the most heavily bicycling cities prior to infrastructure being built, even though there was only a fraction of the bicycle traffic there is now. If there was enough data, I’m guessing it would show accidents rise sharply as bicycle traffic first increases, but then levels off even as bicycle traffic continues to increase.

    About exposure to pollution, I would guess the pollution would go down as bicycle traffic rises, assuming it’s replacing car traffic, and will also drop as motor vehicles become less polluting. Though the advice about moving a block or two where there is less traffic is good advice. In downtown Minneapolis for example, the bike lanes on 4th St. and 6th St. are just two blocks apart, but there is a huge difference in traffic.

  7. Submitted by David LaPorte on 01/08/2013 - 06:28 pm.


    I find it ironic that an article about bicycle safety uses a photo of a cyclist without a helmet as an illustration. I’m a year-round bicycle commuter and never ride without one.

  8. Submitted by Nicole Campbell on 01/08/2013 - 06:29 pm.

    Here’s more data!

    Here’s a literature review published in a peer reviewed journal (and funded by the European Union) that explores the same issues in this article but in a more comprehensive manner:

    Do the Health Benefits of Cycling Outweigh the Risks?

    In the lit review they conclude that “On average, the estimated health benefits of cycling were substantially larger than the risks of cycling relative to car driving”.

    This article (and the title) is trying to scare people away from cycling without even considering all the evidence. I want to see positive or at least thoughtful reflections made by authors when I read Minnpost.

  9. Submitted by Wilbur Ince on 01/08/2013 - 07:57 pm.

    This seems to lack focus.

    YES, biking is dangerous – but compared to what? Is the air pollution more of a harm than the vast benefits derived from biking? At these air pollution levels, are we really at risk?

    On a bigger level, I can say I don’t care about increased risks. I reduce my global footprint. I live a healthier live, and I contribute to an activity that makes my city more livable. Derived statistics can’t compare to that.

    This kind of journalism gives lots of sound bites to bicycle ‘haters’. Does it give the general public any valid information to decide if biking is desirable for them?

    I think not.

  10. Submitted by NIcole Masika on 01/08/2013 - 09:11 pm.

    motorists are the danger

    not cycling! though I have seen some careless cyclists, inattentive motorists are likely to blame for most accidents, and they of course are causing the pollution. Luckily I ride the trail by the river, reducing both hazards.

    And I wish you had chosen a less doomy title because we really need to get more people on bikes

  11. Submitted by Erik Ostrom on 01/08/2013 - 10:37 pm.

    So, to summarize, biking is good for your body and your brain, but it could be safer and even healthier. What could we do that would reduce both collisions and pollution… Oh, I know! BIKE MORE!

  12. Submitted by Andrew Richner on 01/09/2013 - 08:51 am.

    Hmm …

    I don’t know what it is but I feel like the title of this piece led me (and apparently some of the other people posting comments here) to believe this was some kind of polemic against biking, but in reality it seems just to be a summary of some research and statistics on biking.

    I think the anecdote that you lead with about the taxi driver echoes the experiences of a lot of people who bike for transportation (even casually) and aside from illustrating that biking can in fact be dangerous (there’s no denying that), such interactions with drivers illustrates a fundamentally anti-biking culture. In my own experience, I’ve been shouted at that “roads are for cars,” by the passenger in a luxury sedan. I really have to wonder if your taxi driver or my luxury sedan rider would have said the same things to people on motorcycles or riding in horse-drawn buggies.

    Second point I’d like to make is about that statistic that the top cause of bicycle accidents is “failure to yield right of way.” You’ve concluded from this that it’s a matter of bikes blowing through red lights and stop signs and drivers not looking for or seeing bikes. I think that a column devoted to urban planning might look at this statistic with some interest. First of all, why is it that bikes so often blow through stop signs and red lights? I would note that biking is so much more a matter of momentum and the energy costs of starting and stopping are much higher, so frequent stops, especially on corridors like Hennepin Avenue, incentivize bicyclists to blow through red lights, especially in those “barely missed it” cases. Second, “failure to yield right of way” is a traffic error that occurs almost exclusively at intersections. Regardless of which party is at fault, when you have a systemic problem with drivers and bicyclists failing to yield the right of way at intersections, doesn’t it beg the question as to whether at least some of our city’s (and state’s) intersections might need a design overhaul to accommodate the change in traffic composition. Just some food for thought concerning the urban planning implications of that statistic.

    • Submitted by Janne Flisrand on 01/09/2013 - 09:36 am.

      Who’s failure to yield right of way?

      I might also encourage careful examination of the “failure to yield right of way” stats. The data shows that there’s plenty of failure on both sides, and in some types of intersection crashes, it’s almost always the car, whereas in others it’s pretty evenly split.

      I’m looking forward to more in depth bike stat reporting on MinnPost, given the lively discussion (and additional data provided) in the comments.

      • Submitted by Grant Boelter on 01/11/2013 - 11:33 am.

        Re: Right of way statistics

        This gives a pretty good breakdown here:

        Agreeing with most every commenter here, I would really appreciate more careful and thorough examination of these types of issues and less reliance on conveniently choosing statistics that simply confirm the author’s assumption. I also think that it’s somewhat irresponsible (although I understands that it adds entertainment value) of relying on one’s own personal experience to make a point. We’ve all had bad or good experience at one time or another that could be used to add validation to any viewpoint. I would venture to guess that the author has had some harrowing experiences while in a vehicle as well. Each person reacts to certain events differently, but it’s irresponsible to suggest that an activity is dangerous or safe based on the small sample of one’s own personal experience.

        I really appreciate the fact that MinnPost reports regularly on urban issues. It stands out among other publications for doing so. Since bicycling issues certainly would classify as an area for discussion in this space, I’d love to see more articles that address issues like these more thoughtfully.

  13. Submitted by jody rooney on 01/09/2013 - 10:59 am.

    Just to reasure you Mr. Richner

    Horse drawn buggies and bikers often get the same treatment from people even when they are obeying the rules of the road.

    Our road is part of a known “good for biking” road and must make part of an attractive loop because it is used pretty often. It’s a low traffic road it’s pretty scenic and in good condition. I am glad they enjoy it. I wish they patronized the local eating establishment more but…..

    When it was first discovered many of the riders rode several abreast and didn’t know what to do when they saw horse back riders on the road. Within the last few years the riders seem to have “adopted” the neighborhood and wave say hello and call out when they come up behind horses. They have become good neighbors and are no longer perceived as unpleasant or intrusive.

    Perhaps some of the less compliant bike riders who blow through stop signs etc. might want to take a page from their play book and become better road citizens. It looks like it might be better for their health too.

  14. Submitted by Todd Hintz on 01/09/2013 - 12:26 pm.

    Taxi, Please!

    The anecdote about the taxi driver is simply that: an anecdote. It makes for a cute story with a nice sound bite, but other than that doesn’t add anything to the narrative. To contrast, I was also about run off the road by a taxi a few weeks ago. The only difference was I was driving a car when the cab decided he wanted the exit lane that I already occupied. Had our vehicles met at those speeds (and it was a VERY close call) it wouldn’t have turned out well for either driver.

    Do we then conclude that driving is inherently dangerous and should be avoided? After all, look at the number of people who perish in traffic accidents every year.

    The impression I get from all the comments is that people don’t think the article was well researched or written and the conclusion is flawed. Given the general good writing exhibited at MinnPost, they’ve come to expect that all articles follow the same high standard and they’re disappointed that this one doesn’t get the same high marks.

  15. Submitted by mark wallek on 01/20/2013 - 09:22 am.

    Misplaced sentimentality

    There is nothing romantic about biking on the streets today. The wondrous freedom of childhood is not what is happening out there on the roads. “Klutzy” bikers are always going to have a problem, as they are the equalivalent of the distracted driver. And lets be real, the biker contribution to fuel saving is negligible. Many many more bikers would need to be out there year after year to make any substantive dent. So romance aside, bikers need to get on a fast track to road maturity, because they are far from being there. Drivers need to be aware of bikes because they are not going anywhere. And remember this, when it comes to acting stupid on the streets, bikers are more likely to die, and drivers are more likely to be stuck with legal consequences. So everybody, grow up.

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