In Toronto when the temperature goes above 30 degrees Celcius (90 degrees Farenheit), for a few days and without wind, there is smog.

I find the smog irritates and makes it difficult to breathe in through my nose. Worse, if I breathe in though my mouth instead of my nose then it hurts my bronchial tubes.

A related question is, Is pollution a problem in urban cycling? - which says that it is a problem, but doesn't ask whether a mask or other anti-pollution measure is effective.

Might a mask help me for this situation, i.e. breathing on the hottest days? Are they effective and are they usable? If so what type or brands or models should I look for?

  • 3
    possible duplicate of What should I consider when buying a respirator?
    – ChrisW
    Jul 8, 2012 at 18:37
  • 4
    Not a duplicate -- this question asks if the masks are effective, a question not really raised in the other thread. Jul 9, 2012 at 22:32
  • +1 this question is the real deal! Just to share something my ecology teacher told me: how to decide if you are taking a significant amount of pollution. If you feel a bad taste in your mouth, then yes, if not, then maybe.
    – Vorac
    Jul 16, 2012 at 10:11
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    Hey, I was wondering if you made a decision on this? I know the answers can lead you off the idea of buying a mask, specially Daniel's answer, who says it really doesn't make much difference in terms of reducing the amount of pollution. But I still would want to know if it helps, at least a bit, reducing the soar throat and irritation. Did you try any at the end? Thanks for posting question. +1 Sep 23, 2012 at 1:03
  • 1
    @luchomolina, I recently purchased a Respro Metro mask. Observations: (1)heats the air like a scarf: perfect for the winter, but will probably not be good for summer (2) when I take it off, when among traffic, the air smells differently. It is possible that it works.
    – Vorac
    Nov 20, 2013 at 17:39

3 Answers 3


I get this question once in a while (working in Danish Cyclist Federation). It seems to be based on the idea that commuting by bike will expose you to more pollution than commuting by car. I have seen no research that proves this. However, I have seen research indicating that the opposite might be true. Some was in danish, but here's some in english and french (links to pdf's at the end of this article): http://www.pollution-china.com/Blog/More-exposed-to-pollution-in-a-car.html

You should also consider the possible danger of wearing a mask while being physically active. There has been little research in this field that I'm aware of but there could be a risk of creating negative pressure by obstructing the airway which has been known in some cases to produce pulmonary edema. We (again Danish Cyclist Federation) sent some masks to some danish specialists who concluded that the risk was very small, but since pulmonary edema is a very serious thing, I still want to lead your attention to this. Maybe you can find some research (I would be interested to hear about it).

Also keep in mind that if the research on "in-car pollution" vs "on-bike pollution" cited above is true it is much more important for car drivers to consider wearing a mask than it is for bicycle commuters.

On top of this comes all the additional beneficial factors that bike commuting produces.

Happy cycling.

  • 1
    This also ties into the "pollution gradient", where the pollution is most intense low down between the wheels of the line of cars, and reduces more or less linearly away from that area. So the air intakes of cars are right in the zone, and cyclists are in a less intense area. But in heavy traffic it's still really bad. (sorry, no reference to hand)
    – Kohi
    Jul 9, 2012 at 22:43
  • The research article link was dead on the site I reffered to. Here you go: socoolinc.com/media/In-car-pollution-report.pdf
    – zob
    Jul 11, 2012 at 15:42
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    One thing to consider on bikes vs. cars is that cars will spend a significantly shorter amount of time in traffic for most trips (unless you are in a very dense urban area).
    – Jonathan
    Dec 11, 2012 at 0:09
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    I wouldn't worry too much over pulmonary edema. Sure, its possible, but considering the other risks associated with urban cycling I'd put it waaaay down on the list. I spent years performing extremely heavy exercise wearing masks, respirators, mixed gas equipment, etc. at various altitudes in the Army and over time interacted with a few thousand people this way (granted, most of them were in good shape) and never encountered a single case of pulmonary edema. Claustrophobic reactions and misplace mammalian reaction to sudden cold, sure, but that's mere discomfort and trainable.
    – zxq9
    Apr 9, 2014 at 1:36
  • If you change air while in countryside then close windows and use air conditioning in loop, while also having a particle filter... there's no way you get more pollution in a car compared to a bike. Anyway, good point that you mention air resistance and injury to the lung. More than edema, I would point pneumothorax, where lung stop sticking to its enveloppe.
    – bokan
    Sep 5, 2016 at 15:28

To answer this question (which is different from asking "Which mask?") you have to define what "pollution" means and then examine the available masks to see if they do anything to reduce it.

Just offhand, I believe that "pollution", in an urban traffic setting, consists of carbon dioxide, carbon monoxide, sulfur dioxide (and various other sulfur compounds), nitric/nitrous oxide (and various other nitrogen compounds), and soot (which contains a significant amount of unburned hydrocarbons). (Lead used to be a significant component of exhaust but is no longer, with unleaded gasoline.) Of these, only the soot is really "visible", while the sulfur and nitrogen compounds can contribute to "yellow haze".

A simple filter mask will remove only the soot (if that). You need a mask containing at least a reasonable layer of activated charcoal (ie, a canister) to remove much of the others. The masks I see advertised just have a thin layer of "activated charcoal cloth" or some such, not enough to make a noticeable difference.

I was unable to find any evidence of rigorous testing of these masks anywhere -- by the manufacturers or independent bodies. They do test for particulate filtering, but that's of minimal value, and, besides, you can buy (much) cheaper particulate filters if you skip the "pollution" moniker.

  • I have tried a builder's mask with a single canister ... and it was suffocating. What do you think about those masks, that have two canisters in parallel (I think spray paint workers use them)?
    – Vorac
    Nov 21, 2013 at 8:26
  • @Vorac - I've never tried them, but I seriously doubt that they could work for someone engaged in strenuous cycling -- to much restriction. Might work for more casual cycling. Nov 21, 2013 at 11:48

I know of at least one peer-reviewed article which shows that wearing a (proper) filtering facemask does have noticeable effects on one's vital signs compared to when not wearing a facemask.

However, some people still say that they make very little difference in terms of long-term health effects. Moreover, the actual quality of the "filtering" of masks varies wildly — Each has different tests done on it by different companies... and even on different parts of the mask: Some certify the filters themselves but don't have a certification for how much air goes through the filters as opposed to past the sides of the mask (and is therefore unfiltered).

Finally, although it is merely a personal anecdote, for about a year I commuted on a heavily-trafficked route and would have a runny nose and a scratchy throat when I arrived at my destination. I then ordered a mask from totobobo and saw that the filters were indeed getting visibly dirty over little time, so something must be happening. I also noticed less nose-running and throat stratchiness — but this could just as easily have been a placebo effect, a random change in average pollution levels or a number of other confounding variables.

So, I'd tentatively say that yes, a good facemask can be (somewhat) effective at reducing the amount of particulates and other pollution a cyclist inhales while travelling through heavily-polluted areas. Whether the amount it is reduced by is enough to make a significant health difference, I can't say. However, when riding on especially heavily-trafficked roads for a longer period of time (either on a pushbike or a motorbike), I do still get out the mask, 'cuz I'm paranoid like that.

  • The fact that a filter is stopping something you can see tells you nothing at all about whether it's stopping the things you can't see.
    – nekomatic
    Sep 7, 2016 at 11:23
  • 1
    Very true, and the really scary stuff is too small to be visible. Still, the discoloration means it's at least doing something. Sep 7, 2016 at 15:45

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