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Air Quality

One of the questions people often ask of bike commuters is "aren't you exposed to a whole lot of air pollution while biking in traffic?"

Here is a survey paper I unearthed which reports that cyclists are exposed to less pollution than automobile drivers (but more than transit users)

I do question their concern over CO. I don't claim to be an expert but it was my understanding that transient sub-acute levels of CO are not particularly harmful in the long run -- as long as the blood O2 sat remains within normal ranges. (which may well not be true halfway up Greenfield Ave ;S ) Anybody here know better? stefb?

2010-11-10 16:36:47

All I know is it sucks to be stopped behind a diesel-powered vehicle at a light, and its best to try to avoid them whenever possible.

2010-11-10 18:03:16

Sometimes I wonder what I'm sucking in when I ride past that cement plant on 2nd Ave.

2010-11-10 18:09:37

Yeah. Being behind diesel busses just sucks, period. I really like the hybrid busses. Propane and natural gas might be even better.

2010-11-10 18:22:37

fine particulate is known to increase heart disease deaths. still, the protection of being physically active would be greater than the pollution exposure. of course everyone is exposed anyway even if they aren't "out there" this affects indoor and outdoor air quality and while driving as well.

2010-11-10 19:36:50

A phun phigure to know: the healthcare "externality" of urban air pollution - largely from motor vehicles, esp. diesel - is estimated at $26-61 billion per year in the US (M.A. Delucchi & al., J. Environmental Mgmt, 64, 139-152, 2002). Not quite as directly convincing as that awesome article by Elly Blue but still a good lil fact.

2010-11-10 20:23:11

I know that all of Port Authority's buses use "clean diesel" fuel. About half of the buses have the 2006-standard engines, which are a good bit cleaner than the old ones. Even some of the middle-age buses have been retrofitted with newer engines.

A couple weeks ago, I watched a PAT bus and a cement truck pull away from a light at the same time. The bus exhaust had a translucent color. The cement truck belched a huge black cloud. No comparison.

2010-11-10 23:45:09

as the owner and reluctant driver of a diesel vehicle, I'd like to take this opportunity to apologize for my vehicle and myself. That's Reason #17 Why It's Better For Society At Large If I Do Not Drive.

I heard that Lincoln/Larimar/Homewood has the worst air quality in the city, with particulate matter and CO2 higher than Some Official Government Bureau's recommended levels by orders of magnitude. I wish I could remember where or more details. Sad.

2010-11-11 13:35:10

OT, but...

Slightly increased CO2 exposure as a result of cycling poses a nearly insignificant threat compared to the cancerous stew our water is being made into as a result of fracking to drill the natural gas out of the Marcellus Shale.

PWSA has detected elevated levels of THM's and bromides in both the Allegheny and Monongahela Valleys.

Bromides cause cancer, and all the brita filters in the world can't protect you.

Drill baby drill! Yee-haw!

2010-11-11 16:21:28

Frackin' terrifying.

2010-11-11 17:28:39

It's okay, the Clean Water Act will get them, right guys? Right?

2010-11-11 18:34:29

ejwme: Why not run grease in yer diesel?

2010-11-11 19:39:00

Interesting timing, there was a seminar today at CMU about studying/tracking/modelling ultrafine (<100 nm) diesel particulate emissions. One of the more interesting finding is that hybrid buses emit about 2x more particulates than regular ones, and also their GHG savings are only like 10%. Wtf?

2010-11-12 18:53:47

double post, sorry.

2010-11-12 18:57:35

the other day i was behind a bus that spewed out disgusting black exhaust. i contemplated pulling over to write down the license plate so i could call the city to complain. it really grossed me out.. and i couldn't really breathe.

2010-11-12 18:57:37

alnilam, wtf indeed. I'd be very interested in hearing more - is there a published/preprint paper out?

2010-11-12 19:29:22

His talk was pretty much directly from this paper:

Sonntag, Gao, and Holmen, "Variability of particle number emissions from diesel and hybrid diesel-electric buses in real driving conditions," Environmental Science and Technology, v 42, no. 15, pp 5637-5643, 2008.

Except some other facts, like the 10% GHG reduction one, were thrown into his talk but not in the paper. The paper doesn't really offer much explanation for why the hybrid diesels suck for particulate emissions.

I can't access this one, but you may also want to check out this one.

2010-11-12 20:21:56

I only read the abstract, but it says they tested a grand total of four buses, two of them hybrids. That seems like a very small number to draw any conclusions about hybrid buses in general.

I'd think for such a general conclusion, you'd want to test a variety of buses from different manufacturers, and ideally more than two instances of each model.

2010-11-12 23:37:41

check the Pennsylvania Department at the Carnegie Library in Oakland - "Talk" to a dead Pittsburgher who worked middle management: How many shirts did they wear in a day and how long did they live - chain smoking excluded?

I like the "global dimming" phenomenon occurring in parts of southeast asia. Throws a nice variable into the man-made warming theory.

2010-11-13 00:57:15

that visible smog/soot pollution is not as much of a health problem because the particles cannot directly enter the bloodstream the way the fine particulate does.

2010-11-13 01:26:53

spakbros - I don't run grease for a handfull of reasons, two major ones though: Giving up trunk space for the grease tank defeats most of the purpose of having that car, it's really expensive (for me, right now) and I can't do the mod myself. Also, by the time I earn back the cost of the mod, I hope to be car free. Or at least have our household down to one car.

But whether it runs diesel or grease, aren't there still particulates and waste gasses that are... less than benign? All combustion has byproducts, no matter what's combusted, and they're rarely rainbows and puppies. That'd be awesome if my car pooped out rainbows.

2010-11-15 16:28:42

A vehicle powered by hydrogen that was produced using solar and wind would be pretty close to actual rainbows.

2010-11-15 16:54:52

Clean up yer damned rainbows!

mutter. effin hippies leavin' rainbows everywhere... Somebody's gonna slip and fall.

2010-11-15 16:59:22

If you got the water to exhaust in a misty spray, there could be actual rainbows. Let's do this.

2010-11-15 17:02:22

did someone say rainbows?

2010-11-15 17:09:13
When Bain rides a bicycle...
2013-11-20 16:06:36
Does anyone here ride a bike in Larimer? The Kingsley Association is looking for help monitoring air quality. VOLUNTEERS NEEDED To Monitor Air Quality by Bike in Larimer Wed. July 15th 7:30 am, 12 pm and 4 pm Thurs. July 16th 7:30 am, 12 pm and 4 pm Volunteer Orientation Tues. July 14th 11:30 am or 6 pm *each session will last 1 1/2-2 hours, meet at the Kingsley Association Register HERE to select your times. Or Contact mmaeda (at) 412-661-8751 ext. 106 Facebook:
2015-07-13 10:07:47
New York Times article: "... wears sensors that monitor how much air he breathes in during the trip, along with air pollution levels along his route. This elaborate gadgetry is part of a five-year study that aims to find out at what point the harm done by pollution to cyclists might outweigh the health benefits accrued from the exercise."
2017-07-15 00:42:53
Pedestrians walking along a busy road breathe in less air pollution than occupants of the cars on that road. "The most obvious way to reduce your exposure to pollution in the car is to drive less", the article says.
2017-08-16 23:35:10
There is a well known "near roadway" effect for air pollution health effects.  We (mostly not me but other colleagues at CMU) are currently conducting very high spatial resolution measurements of air pollution in Pittsburgh, and one of my students just presented an analysis he has conducted showing that the rear end of a bus is roughly as dangerous as the front end - deaths from bus air pollution are about the same as deaths from being hit by a bus.  We estimate 1-3 deaths per year in the county from bus emissions.  As a rough guess, the air pollution risk on roads is at most twice the urban background value, but indeed it is not riskier being on a bike than in a vehicle (except perhaps for the higher VO2...).  Overall, on average air pollution increases your risk of mortality here by about 2% - something like 260 of the 13000 deaths per year at attributable to fine particulate matter pollution, mostly in the form of increased heart attacks caused when fine particles trigger systemic inflammation, which in turn increases rick of atherosclerosis.  So hanging around roads increases your risk of death by a percent or two.  The question is, does getting fit via cycling decrease your risk of mortality by more than that.  Surely yes.
2017-08-17 12:39:04
Not riding a bicycle can be hazardous to your health. Another study: "For individuals who shift from car to bicycle, we estimated that beneficial effects of increased physical activity are substantially larger (3–14 months gained) than the potential mortality effect of increased inhaled air pollution doses (0.8–40 days lost) and the increase in traffic accidents (5–9 days lost). Societal benefits are even larger because of a modest reduction in air pollution and greenhouse gas emissions and traffic accidents."
2017-08-17 14:15:11
Note as well that air pollution is quite a bit riskier than vehicular mortality - 260 per year in the county to about 85 per year, so about 3x.  Furthermore, the health risk from pollution and the health benefits from exercise are within the same physiological mode - cardiovascular health and risk - so it is a very reasonable hypothesis that cycling strongly mitigates the risk of exposure to fine particles, over and above the general risk reduction.  To my knowledge nobody has looked at this potential synergy. Anybody who wants to chitchat with me about this can head out on the 100k Pedal Pgh loop at 6:30 or so or on most of the upcoming DD training rides.
2017-08-17 14:25:40