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I live in Chicago, and I ride through the downtown area and other congested streets to and from work every day. Often when I am at a stoplight, I am directly behind or next to several cars belching exhaust. I can't help but smell and inhale it. Sometimes I try to hold my breath, but I can't always hold it for long enough. It smells bad, and I do not wish to inhale carbon monoxide. Is there some great product out there, or maybe just some tips and tricks from other city riders, on how to avoid inhaling exhaust fumes while riding through heavily trafficked urban streets?


I believe my question is similar to or the same as the suggested duplicate about "how to protect yourself from pollution", however that question has no usable answer (The answer is basically "a gas mask would help, but of course you cant go biking with a gas mask"). I believe my question is not the same as "is pollution a problem" because I am not making/seeking a judgment on pollution, positive, negative, or otherwise, I am just attempting to avoid it/minimize my exposure.

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Possible duplicate of How to protect yourself from pollution in city cycling – Tom77 Oct 1 at 6:20
Possible duplicate of Is pollution a problem in urban cycling? – Mσᶎ Oct 1 at 6:23
The 'gas masks' answers all revolve around the idea you need some military-style mask which actually protects you from gas but that idea might not even be entirely correct. For all you know it is possibe most health risks comes from what you call 'bad smell' as those are small particles which can settle in your lungs, and not from the carbon monoxide. As such it is possible a light half facepiece respirator with adequate small particle filter provides ample protection. Again, I say possible as I think matter like this requires proper scientific resaerch/evidence to provide a correct answer – stijn Oct 1 at 7:59
Serious answers: try being on the side away from the tailpipe. Get in front of the cars at the lights - don't queue in line with them. Take routes that are less car-congested, even though they may be longer. Less serious answers: stay away from any Volkswagen Diesels :-0 – Criggie Oct 1 at 8:25
@chiliNUT I wouldn't go that far, but the evidence suggests that you're better off biking in the fumes than not biking. I'm more trying to suggest that if you know what you're trying to avoid it's easier to avoid. Otherwise you're left with holding your breath at random times, hoping that you damage yourself less by oxygen deprivation than you would by just breathing the fumes. – Mσᶎ Oct 1 at 23:27

3 Answers 3

From The Guardian: (I suggest you Click through & read the whole article)

"It’s a scenario familiar to any urban cyclist: you’re stuck behind a fume-belching bus or taxi, a choking diesel aroma wafting through your lungs. You think: is this really the healthy option?

The good, if simple, answer from pollution experts is: yes. Cycling does remain many, many times better for your health than not cycling, even factoring in exposure to pollution and the risk of accident. What’s more surprising is that on two wheels you might even be exposed to less of the smelly stuff * than those using other forms of transport." *(Emphasis added.)

I have read elsewhere (although I can't find the link now) that this lower exposure is due simply to the fact you are up higher than a person in a sedan, and the pollutants tend to sink.


It's not so much that the rider is higher up, but that the cabin air intake of a car is effectively at exhaust pipe level

(Thanks @Chris H)

The science is out the anti-pollution masks, not so much because they are incapable of performing their advertised function, but because exposure levels are much lower for the typical cyclist than most people suppose.

Edit two:

To attempt to address the last crux of your question, it may be reasonable to say that you are already avoiding more exhaust just by biking & not driving, other than that; take a less heavily trafficked route & otherwise don't worry about it.

I suspect general air quality should be more of a concern than incidental exhaust exposure.

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It's not so much that the rider is higher up, but that the cabin air intake of a car is effectively at exhaust pipe level. – Chris H Oct 1 at 15:25
Good answer. If possible can you please include links to the remainin original research. I recall reading these studies a while ago, so I will look through my library as well. – Rider_X Oct 1 at 16:33
Ahh, good point @Chris H. I'll edit that in. – renesis Oct 1 at 16:45

There are two points to consider. As explained by @renesis even though you are exposed to pollutants, your overall exposure does not appear to differ significantly from car drivers (note the study was carried out in Copenhagen, I am not sure automotive how pollution regulations compare to the US). Because you are also getting exercise, your overall health outcome is likely better than remaining inactive inside a car.

That said, there are ways to reduce your exposure. A 2008 study looked at the exposure by taking differ approaches to commuting:

  1. Choosing a low exposure route (i.e., longer and more out of the way, but less traveled by automotive traffic.
  2. A faster (more direct) but in more dense traffic (shorter exposure period, but higher exposure levels).
  3. Taking the bus (a positive control - buses tend to take direct routes on busy streets)

They found that accumulated exposure (i.e., total exposure over the course of the trip) was 54%-67% lower on a low exposure route. The authors also suggest that riding in off-peak hour will further reduce exposure.


The best way to reduce pollution is to avoid contact. If you have flexible work hours, you may want to start work earlier. I find if I come to work one hour earlier (i.e., 7 am start rather than 8 am) the amount of traffic I encounter is almost an order of magnitude less. Depending on where you live and distances traveled you may want to scour your local maps to find routes that are on green-ways rather than with traffic.

In my opinion it is all about incremental gains (err... losses). (Kind of like time trialing, but that is a different topic altogether!)

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Good point on starting work earlier, the Guardian article I linked to mentioned the accumulation of Ozone increasing throughout the day, citing that as "the reason endurance events at the London 2012 Olympics, like the marathon, were mainly scheduled in the morning." Ozone is probably more of a concern than Carbon-Monoxide. – renesis Oct 1 at 17:04
@renesis - CO does play a role in ground-level ozone production. Can't win can we? – Rider_X Oct 1 at 17:11
Well how about that... +1 – renesis Oct 1 at 17:16

Because anti-pollution masks contribute to overheating (that's my experience), they are an option in colder climates or during winter. Not only it is filtering the air, but is also warming it and your face. Get a double-filter one for less air resistance (theoretically half - parallel air restrictions act just like parallel resistors).

Another point is that the vast majority of exposure to high-density car pollution is while waiting on a traffic light (there was an article about this somewhere). Consequently - try to manoeuvre out of that. If you are riding to the side of the road, you can learn the traffic patterns and when approaching a traffic light to slow down until you expect it to turn green very soon. If you are riding like a car, in the middle of the lane, I suspect you could still manoeuvre your way to the front of the column, where I imagine the pollution buildup would be lesser than in the centre of the column.

And as my Ecology professor said - don't ride directly behind the bus :D

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