Sooty lungs alert! (or Cycling is dangerous, wear a helmet)

unionman

Lungs of cyclists may be sootier

MUIRIS HOUSTON

Mon, Sep 26, 2011

PEOPLE WHO cycle through London and other major cities have higher levels of black carbon in their airway cells than those who walk to work, research published yesterday suggests.

Black carbon particles (soot) are known to cause lung and heart damage. The small preliminary study involving five commuting cyclists and five pedestrians was carried out by researchers from St Bartholomew’s Hospital and the London School of Medicine. They took samples of cells from the participants’ lower airways. These cells, called macrophages, sit on the surface of the airway ingesting foreign material such as black carbon, a byproduct of exhaust.

The research presented at the European Respiratory Society’s Annual Congress in Amsterdam, suggests that cyclists inhale more black carbon than pedestrians. In this small study, cyclists had 2.3 times more black carbon in their lungs compared with pedestrians

Combustion of fossil fuels results in large numbers of inhalable particles of soot. There is increasing evidence inhalation of black carbon particles is associated with a wide range of health effects – including heart attacks and reduced lung function.

The researchers collected sputum samples from five adults who regularly cycled to work and five pedestrians, and analysed the black carbon found in their macrophages. All participants were non-smoking, healthy urban commuters aged 18-40.

Dr Chinedu Nwokoro, one of the researchers, said: “The results of this study have shown that cycling in a large European city increases exposure to black carbon. This could be due to a number of factors, including the fact that cyclists breathe more deeply and at a quicker rate than pedestrians while in closer proximity to exhaust fumes.”

© 2011 The Irish Times

Beasty

.... we're all gonna die!!!!

unionman

...non-cyclists die every day.

Beasty

... good point - and most cyclists don't die until after they've given up cycling. Therefore if we all keep cycling there's a fair chance we'll live forever ...

rp

yeah but so are 'they':

Car occupants have a significantly higher level or exposure to engine emuissions than people outside vehicles.

ref here

ednwireland

shoulda seen the state of my repro mask after a week of cycling into work in derby, used to get continuous watery eyes and sniffles stopepd when i started wearing a mask

Jawgap

....but do they stay there?

I thought one of the benefits of cycling was that the streaming eyes and nose helped clear things like soot particles and and dust quickly - whereas stuff inhaled while sitting in a car or walking tended to remain in there longer.

seamus

British cities are particularly bad for this. Any time I go to London, you end up blowing you nose and looking at a black tissue, it's pretty worrying.

No Irish cities are particularly dense or high-rise, so there's less accumulation of these particles in the air.

Lumen

In Dublin it's the buses that spew out the filth.

tomasrojo

Is 2.3 times the amount of black soot an important difference? I don't know.

Commuter cyclists live a few years longer on average than commuting non-cyclists, so I doubt the black soot effect is more important than the benefit of frequent low-impact exercise.

tomasrojo

Lumen wrote: »

In Dublin it's the buses that spew out the filth.

I don't know about the soot effects, but I know a bit about PM10. Burning diesel (as buses do) rather than petrol results in higher levels of PM10 (particulate matter of 10 microns aerodynamic diameter or less). PM10 is important, because it's small enough to penetrate deeply into the lungs.

Report here:
http://www.epa.ie/whatwedo/monitoring/air/reports/pm10/

There are quite a few breaches of daily limits, but nowhere exceeds 35 breaches per year, which I guess is regarded as a Bad Thing (the EU will intervene, I think, at this point).

kuro_man

This study doesn't show anything - 5 is too small a sample size and it doesn't include motorists, motorcyclists, bus passengers etc. Maybe the 5 cyclists smoke cigars at the weekend!

Regarding air quality, I heard Dublin is much better than London because of the weather - more wind, less inversion - rather than population density.

Pherekydes

tomasrojo wrote: »

Is 2.3 times the amount of black soot an important difference? I don't know.

More is bad, I'd say.

Having said that, this study compares two five-person samples. The standard error is 45%, so the confidence intervals will overlap, hence the difference is not statistically significant. Interesting for sure, but a much larger study would need to be done before any conclusions could be drawn.

Mucco

seamus wrote: »

British cities are particularly bad for this. Any time I go to London, you end up blowing you nose and looking at a black tissue, it's pretty worrying.

They're trying to reduce the pollution in London:
Low Emission Zone

HivemindXX

Someone either did, or was talking about doing, a similar study here a few years ago. Few might mean 10+ by the way.

There had been a similar article to the one the OP quoted which seemed to be suggesting that cycling was actually bad for you. The study was supposed to test the theory that drivers actually had similar or greater amounts of particles because the air intakes in a car neatly line up with the exhaust of the car in front and the filters don't stop the small particles that we were supposed to be worrying about.

About 20 years ago, before the coal burning ban in Dublin, there was at least one year where the air was noticable polluted (as in everything you looked at was tinted yellow by the air pollution) and some pedestrians were wearing filter masks. If we hadn't stopped that situation I doubt anyone would be cycling or walking if they could possibly avoid it. The solution wasn't to keep polluting but stop people going outside without breathing gear on.

I tried to find the original study so I could see if they had the pedestrians go an equivalent distance or spend an equivalent time but I couldn't. If anyone does find a link to this please post it. I did find a ton of news stories about this.


I'm already arming myself with counterarguments:-

• I personally feel a lot fitter and healthier since I started cycling. I don't know what the effects of this particle build up in your lungs is supposed to do but I know I used to have occasional breathing problems that required me to use Ventolin (the asthma inhaler) and that completely cleared up since I started cycling every day.
• A cyclist is supposed to pick up 2.3 times as much soot as a pedestrian. Is that in the same time, because even on a slow day I go three times as fast as a walker? If it takes me 10 minutes to cycle to work and it takes you 30 minutes to walk then you'll have more soot in your lungs that I do.
• It's interesting that there's no clear indication of what the medical effects of this are. It also doesn't say how much more of this stuff both cyclists and walkers in the cities have than those in the countryside. If it turns out that urban walkers have 10 times the amount of soot that rural walkers have then perhaps we should be looking at car emissions instead of trying to scare cyclists off the roads. It's also interesting that there's no information on how much of this soot car drivers have in their lungs over an equivalent distance. Air intakes on cars are right down where the exhaust of the car in front is, and car air filters only stop the larger particles. I'd like to know how motorists compare to cyclists in this regard, it's weird the study didn't show that isn't it?

tomasrojo

Pherekydes wrote: »

More is bad, I'd say.

But you still need some context of how bad the amount of soot is to begin with. I might drink twice as much beer as my friend, and that makes me sound like a heavy drinker, but he drinks one glass of beer a week.

tomasrojo

kuro_man wrote: »

This study doesn't show anything - 5 is too small a sample size and it doesn't include motorists, motorcyclists, bus passengers etc. Maybe the 5 cyclists smoke cigars at the weekend!

Regarding air quality, I heard Dublin is much better than London because of the weather - more wind, less inversion - rather than population density.

The Irish Times report says that all ten participants were non-smokers.

But this study is too small to conclude anything really -- although its conclusion isn't implausible.

I think you're right about the lack of inversion events. I used to work in Orange County and you could see the sunsets wax increasingly spectacular during calm weather, as the trapped particulates scattered more and more frequencies of the light from the setting sun. When it rained or the wind blew, the sunsets became pallid again.

tomasrojo

Pherekydes wrote: »

Having said that, this study compares two five-person samples. The standard error is 45%, so the confidence intervals will overlap, hence the difference is not statistically significant. Interesting for sure, but a much larger study would need to be done before any conclusions could be drawn.

I bet the difference is not statistically significant. But, to be pedantic, confidence intervals can overlap and the difference still be significant.

http://en.wikipedia.org/wiki/Confidence_interval

If two confidence intervals overlap, the difference between the two means still may be significantly different

If you're comparing percentages, a z-test probably would be the best way to decide whether the difference is significant.

tomasrojo

HivemindXX wrote: »

The study was supposed to test the theory that drivers actually had similar or greater amounts of particles because the air intakes in a car neatly line up with the exhaust of the car in front and the filters don't stop the small particles that we were supposed to be worrying about.

Mayer Hillman was pushing the idea that cars should have the exhausts placed on the far side, rather than the near side -- that is, in Ireland, on the right of the car rather than the left. I presume that they're put on the left so that the emissions are not pumped directly at the driver behind, but Hillman argued that pedestrians hardly deserve to be directly in line of the emissioms.

The positioning of exhaust pipes at the rear of vehicles can be cited as a particularly effective means of reducing the attractions of walking. Anyone whether in a vehicle or on foot can carry out an observational survey of the current situation by a simple count. It will reveal that the great majority – between 80% and 90% – are located on the left-hand side. As a consequence, the toxic fumes are expelled at low level in the direction most damaging to the health of pedestrians, especially small children, those in pushchairs, and cyclists – not to mention diminishing other qualitative aspects of the local environment. The fumes also remain suspended for some time before settling, thereby increasing the period of exposure to them.

Two suggestions can be put forward to remedy this unfortunate outcome. First, and obviously, legislation could easily be passed through Parliament requiring manufacturers to fit exhaust pipes on the right-hand side of all new vehicles for the UK market. This should pose no problem for sales in countries in which vehicles are driven on the right: after all, vehicles for use here have their steering wheels on the right side – and for use on the Continent on the left side.

Second, albeit more contentiously, a strong case could be made for legislation requiring exhaust pipes to be fitted at the roof level of vehicles. This would have the advantage of ensuring that the fumes were dispersed more efficiently than releasing them at low level. At the same time, it would alert road users to the immediate toxicity of the air they were breathing and enable them better to avoid inhalation of the fumes. As they would be more visible, the general public would be more aware of this health hazard which in turn could lead to more political pressure for stricter regulations on the composition of the fumes.

http://www.mayerhillman.com/Home/Mayers-Musings/EntryId/9/14-The-positioning-of-vehicle-exhausts.aspx

Lumen

"Second, albeit more contentiously, a strong case could be made for legislation requiring exhaust pipes to be fitted at the roof level of vehicles."

That is the most obviously stupid idea I've read in ages.

tomasrojo

Lumen wrote: »

"Second, albeit more contentiously, a strong case could be made for legislation requiring exhaust pipes to be fitted at the roof level of vehicles."

That is the most obviously stupid idea I've read in ages.

He's famous for his "counter-intuitive" thinking. I suppose, to paraphrase Spinal Tap, there's a thin line between counter-intuitive and stupid.

seamus

HivemindXX wrote: »

A cyclist is supposed to pick up 2.3 times as much soot as a pedestrian. Is that in the same time, because even on a slow day I go three times as fast as a walker? If it takes me 10 minutes to cycle to work and it takes you 30 minutes to walk then you'll have more soot in your lungs that I do.

Well it's about the volume of air inhaled, surely. At the most basic level if you compare calories burned, then it's conceivable that 10 minutes cycling consumes more air than 30 minutes walking.

You would also have the issue that cyclists are in closer proximity to the vehicles, so the amount of exhaust taken in would be more.

Your counterarguments are valid, but I don't specifically see any reason why their results would be wrong.

rp

Lumen wrote: »

"Second, albeit more contentiously, a strong case could be made for legislation requiring exhaust pipes to be fitted at the roof level of vehicles."

That is the most obviously stupid idea I've read in ages.

Au contraire, Blackadder: with the rising sea levels caused by greenhouse gas build-up in the atmosphere, such mods (along with an intake schnorkel) will be indispensable to allow the motorist to keep on motoring to the bitter end...

HivemindXX

seamus wrote: »

Well it's about the volume of air inhaled, surely. At the most basic level if you compare calories burned, then it's conceivable that 10 minutes cycling consumes more air than 30 minutes walking.

It's certainly possible. However I'd like to know for certain whether this is distance equivalent or time equivalent.

I think there's a certain game played by the media with studies like this. I've found in general the studies themselves are very dry and boring, full of equivocations and warnings not to jump to conclusions. The media then takes this study, cuts out all the boring bits, finds the nearest shocking conclusion and jumps to it.

The impression created by any of the articles I read about this study is that cycling is actually dangerous. They don't indicate whether this level of this type of particle in your lung is a health hazard, they just imply that it is. Sometimes they state that in the headline without backing it up in the body.

In general I'd like to get to the actual facts. However in the absence of them, in the conversations I am bound to have over the course of this week which start with "did you hear how dangerous cycling is due to filling your lungs with soot!" I intend to use anecdotes about my own health and throw up a bunch of questions about the scientific basis of this study (or rather the medias interpretation of it) to create the impression it might all be simply ginned up out of nothing to sell newspapers on a slow news day. I won't feel any guilt about doing that, as far as I'm concerned I'm simply fighting fire with fire.

nomdeboardie

Second, albeit more contentiously, a strong case could be made for legislation requiring exhaust pipes to be fitted at the roof level of vehicles.

Funnily enough, this thought occurred to me before I got to that bit - but only for buses /high trucks. Would be interesting to see whether having the exhaust ('chimney'?) pointing up and out from the right side of the roof would decreace the concentration of particulates at the level of the average cyclist's head. I sometimes wonder if the emissions from buses aren't even worse per passenger-mile than cars. +Surely there must be some additional filtering that could be applied to their exhausts. Meanwhile, I'll be continuing to keep a few car lengths back from the back ends of buses /hold my breath /breathe through my sleeve /maybe get a mask to keep around my neck for bus attacks. Looking at the Wikipedia "particulates" page on health effects is depressing, [disclaimer]although I can't say I've read much of the primary literature[/disclaimer].

tomasrojo wrote: »

I used to work in Orange County and you could see the sunsets wax increasingly spectacular during calm weather, as the trapped particulates scattered more and more frequencies of the light from the setting sun. When it rained or the wind blew, the sunsets became pallid again.

:pac: I have fond memories of LA smogsets (and that was after they'd started cleaning up the emissions a bit).

kipple

HivemindXX wrote: »

I tried to find the original study so I could see if they had the pedestrians go an equivalent distance or spend an equivalent time but I couldn't. If anyone does find a link to this please post it. I did find a ton of news stories about this.
[/LIST]

I have read some research on this and IIRC the pollution from car exhausts drops off dramatically with distance. So pedestrians are inhaling much cleaner air as they are usually further away from the car exhaust and. I am guessing it is like a d squared law.

monument

Not including motorists, their passengers and even public transport uses is strange.

And does it compare cyclists and people walking over equal distance or different distances? Ie a cyclist spending an hour around traffic isn't really comparable to a pedestrian only being around traffic for 20mins.

reallyunique

Another "Cycling Is Dangerous" article. Cycling has conclusively been shown to improve the health of the cyclist in the long term regardless of other effects including, but not limited to, accident damage, activity related injuries, breathing deeply and being attacked by dogs.

Bad, bad, science reporting! The only useful piece of information in the entire article was the quote from the researcher which was, in itself, wrong. The statement that results have "...shown that cycling in a large European city increases exposure to black carbon." is false as the sample size is too small to "show" this. At best it might possibly suggest it. Also, the choice of London suggests an attempt by the researcher to skew the data. Try the same study in Copenhagen and then extrapolate to other large European cities. I guess he wants car manufacturers to fund a bigger study.

This is a preliminary study and no extrapolations should me made on the basis of it. No information on the actual quantity of "soot" found was mentioned. There was no information as to whether the levels found would be considered to be detrimental to health or not. The researchers did not claim that there were ANY health effects related to the increase in "soot" in the cyclists lungs.

This is what happens when a scientist looking for money meet a reporter looking for money.

Edwardius

Found the abstract here (P1037):

http://www.ers-education.org/ersMade/abstract_print_11/files/105.pdf

Surprised someone got in the news from a poster, not even a talk! Only reason I'm linking it that the actual levels are shown. Dunno if they're levels that would cause an increase in any sort of respiratory shenanigans though. It seems that the measurement technique is new so there mightn't be a lot to compare it to. Also, the first author is a cyclist!
Edit, also, the cyclists were on average 6yr older than the peds.

Victor

It doesn't seen to mention whether this material is PM10 or PM2.5 (considered much worse as it pentrates the lungs more).

seamus wrote: »

Well it's about the volume of air inhaled, surely. At the most basic level if you compare calories burned, then it's conceivable that 10 minutes cycling consumes more air than 30 minutes walking.

I'm inclined to so no. Cycling X distance would tend to be more fuel (and therefore air) efficient than walking X distance, largely due to the body having an energy demand.

Lumen wrote: »

"Second, albeit more contentiously, a strong case could be made for legislation requiring exhaust pipes to be fitted at the roof level of vehicles."

That is the most obviously stupid idea I've read in ages.

If the vehicle is a bus or a lorry?

HivemindXX

Thanks for posting the link. There's a number of issues to pick at with what's there.

For one thing the cyclists are said to have 2.75 times the amount of exercise in a week but that's not significant, but the 2.3 factor of soot is significant for some reason...

Looking at the chart the spread of results for the cyclists screams at me that 5 points is not enough to draw a conclusion. To be fair the pedestrian points are nicely grouped and would seem representative.

As Ed pointed out the cyclists are six years older on average. Perhaps this means older residents of London have more soot in their lungs.

How did the researchers determine this soot was a result of cycling? We already know the cyclists take a lot more exercise than the pedestrians, perhaps this is outside in the soot filled air. We also already know that the cyclists are substantially older than the pedestrians, perhaps the soot builds up over time. We have no idea what the medical implications of having this soot in your lungs is. Mineral water contains plenty of elements that would be toxic in larger doses but we don't get worried when we hear "Brand X water has 2.3 times the amount of heavy metals contained in tap water".

I'm not planning on retiring my bike as a result of this study.

n-dawg

HivemindXX wrote: »

• A cyclist is supposed to pick up 2.3 times as much soot as a pedestrian. Is that in the same time, because even on a slow day I go three times as fast as a walker? If it takes me 10 minutes to cycle to work and it takes you 30 minutes to walk then you'll have more soot in your lungs that I do.

Really good point... cyclists spend probably about 1/3 the time on the streets as a walker so overall there is a benifit to cycling