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http://www.cleanmpg.com/photos/data/2/Canadian_Flag.jpg Use electric for expanded rail services (http://www.theglobeandmail.com/news/national/toronto/use-electric-for-expanded-rail-services-health-officials/article1174181/)

http://www.cleanmpg.com/photos/data/500/diesel_smoke_train.jpgBrodie Fenlon - THEGLOBEANDMAIL (http://www.theglobeandmail.com) - June 10, 2009

An age old issue revisited. Is this an overreaction or still a real problem? --Ed.

Trains involved in a major expansion of rail traffic in the city's west end must be electrified to guard against the “particularly harmful” impact of diesel fumes on human health, Toronto's medical officer of health says.

David McKeown, in a report that goes to the city's board of health on Monday, said the province's Toronto-area transportation agency, Metrolinx, should replace the diesel engines in its proposed rail link to Pearson Airport and the expansion of GO Transit service along the Georgetown rail corridor with electric vehicles.

If electric cars cannot be found before the extra trains start running in 2013, the agency should use hybrid locomotives and ultra-low-sulphur diesel, and reduce idling in the meantime to mitigate against the increase in diesel exhaust — a toxic brew of chemicals linked to lung cancer, respiratory illness and other health problems, he said.The report, which also calls for improvements to Metrolinx's air-quality and health-risk assessments, is ammunition to local activists who warned that the expansion will pollute the corridor that cuts through neighbourhoods such as Weston, the Junction and Roncesvalles.... http://www.theglobeandmail.com/news/national/toronto/use-electric-for-expanded-rail-services-health-officials/article1174181/

A failure to consider the displaced particulate emissions of unused commuting vehicles?

Emissions are harder to control on which of these?
a) 1 diesel train
b) 100 passenger cars

I couldn't get the cited article to open, but I did read an abstract produced by the group fighting the diesel trains, advocating Metrolinx bite the bullet and go electric right away.
www.cleantrain.ca/CleanTrainCoalition-TheBetterMove.pdf

As with any advocacy group their arguments have merit, but...

Citing Chicago's air quality experience after years of non-emission controlled equipment is of little value. Today's locomotives need to achieve Tier 3 compliance, definitely dirtier than Tier 5, but much cleaner than older diesels. Unless Metrolinx allows old locomotives to be purchased? And most of Toronto's power comes from a coal burning plant.

Keith

We've had AirCare for maybe 2 decades now, in BC. And while passenger vehicles are getting extremely clean, you see big, older diesel trucks fired up and idling, spewing noxious clouds of smoke as they warm up. Very frustrating!

I breath the exhaust from these diseasel trucks on the way to work. Most of the time I hold my breath. While its harder to clean the big trucks the small light trucks should be gasoline engines or hybrids.

Rail can be electrified too. When my dad commuted to New York from the Matawan NJ platform back in the early 1970's he took a diesel-electric powered train. Today that same platform is electric and the trains are almost exclusively electric now. So it has already been done at least for NJ Transit trains.

If there is such an uproar about diesel, what about coal-fired plants? ;)

Out of sight - out of mind I guess....but not out of our air.

We've had AirCare for maybe 2 decades now, in BC. And while passenger vehicles are getting extremely clean, you see big, older diesel trucks fired up and idling, spewing noxious clouds of smoke as they warm up. Very frustrating!

The worst offenders locally are the buses. Walking to work, I get an objectionably large dose of diesel particulates every time one of these buses goes by. Does anyone know how to tune a dieseld for lower emissions? These things are awful.

Harry

If there is such an uproar about diesel, what about coal-fired plants? ;)

Out of sight - out of mind I guess....but not out of our air.

No fossil fuel is nastier than coal but back during the war of the currents if we had chosen Edison's DC transmission of power over Dr. Nichola Tesla's / Westinghouse AC method of transmission the coal powered electrical generating plants would have be placed every 1½ miles because of the steep resistive current losses caused by low voltage DC transmission. It would have made the public obviously more aware of the cost of using coal.

While uncontrolled diesel engines are responsible for their fair share of particulate matter (PM) emissions, I wish public officials would stop implying that they are essentially the only source of ambient PM, or even the major source. There are a myriad of other sources, including cars as other commenters have noted.

I have been involved in the air quality field for nearly 25 years (since early 1985). Since I've had access to speciated PM monitoring data (early 1990s IIRC), elemental carbon (EC aka "black carbon" - BC) has never accounted for more than 10% - 15% of the ambient PM by mass that I can remember, even in urban settings. Diesel engine PM is mostly EC (60% - 75%), so even if they were responsible for ALL EC, which they're not, they would still only account for about 20% of ambient PM at most.

"Source apportionment" studies have suggested that diesel PM actually accounts for a relatively small portion of total ambient PM2.5 (PM smaller than 2.5 micrometers). One study apportioned only 2% of PM2.5 to diesels (both on-road and off-road) in Washington, D.C. (Eugene Kim, Philip K. Hopke; “Source Apportionment of Fine Particles in Washington, DC, Utilizing Temperature-Resolved Carbon Fractions.” Journal of the Air & Waste Management Association, Volume 54, July 2004, Pages 773-785). This is graphically illustrated on the second slide @ http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2007/poster3/deer07_lawson.pdf . The monitoring data were obtained between 1988 and 1997 which predated use of DPF. That same study apportioned 21% of ambient PM2.5 to gasoline engines.

As far a the "particularly dangerous" assertion leveled against "diesel fumes" in the article, there's no reason to suspect diesel PM is any more "dangerous" than any other PM2.5, especially from combustion sources. At least one study suggests that PM from high-emitting gasoline engines is much more toxic (about five times more toxic) than PM from a high-emitting diesel engine (Mauderly, et al., "COMPARATIVE TOXICITY OF COMBINED PARTICLE AND SEMI-VOLATILE ORGANIC FRACTIONS OF GASOLINE AND DIESEL EMISSIONS." Proceedings of the 2002 DEER Conference). I hold my breath when I get behind an old gasoline "smoker". ;)

"...ARB estimates that about 70 percent of the cancer risk that the average Californian faces from breathing toxic air pollutants stems from diesel exhaust particles..."

http://www.oehha.org/public_info/facts/dieselfacts.html

DAS

"...ARB estimates that about 70 percent of the cancer risk that the average Californian faces from breathing toxic air pollutants stems from diesel exhaust particles..."

http://www.oehha.org/public_info/facts/dieselfacts.html

DAS

ARB says that as thought they know what causes 100% of the cancer risk from toxic air pollutions. Since when?, no need to bother with all the rest of the air pollutants then?

Pure speculation. :biglol:

While uncontrolled diesel engines are responsible for their fair share of particulate matter (PM) emissions, ......

I hold my breath when I get behind an old gasoline "smoker". ;)

The fraction of total pm discharge approach is interesting, but I worry that it may contain something of a comparison of apples and oranges. When I'm doing my work (soil, water), it isn't just concentrations but locations of contamination that matter when considering exposure pathways that effect human health. Dilution effects being what they are, it seems likely that a discharge at ground level near pedestrians has a greater impact on health than the same discharge from a 200 foot tall smokestack in an industrial area with large setback zones. Intuitively, part of the risk is "ambient" and part of it is based on proximity to and duration of exposure to discharge locations. In the case of coal power plants proximity is managed by using tall stacks and setback zones.

I haven't read the combined PM/VOC toxicity article, but I doubt that it treats the issue of exposure pathways/discharge locations sensitively because the math would be pretty hard to get right. I suspect this would particularly matter in the case of VOC/PM comparisons since my impression is that VOC's normally degrade in the atmosphere much more rapidly than PM's.

I guess what I'm saying is that the studies you chose may have metrics that are biased in diesel's favor.

Of course I shouldn't criticize diesel particulate emissions since I heat my house mostly with wood (in an epa-approved wood stove).:o

One needs to keep in mind that dirtier on average isn't necessarily dirtier for the individual. As stated, if an electric train powered by a coal plant and a diesel train powered by....well, anyway if they have the same emmisions. The Electric train will probably be safer as the coal plants emmisions are probably isolated from most people (except the plant workers....I feel for them), where as the diesel trains is pooring out its nasties inside a concentration of people.

As was said, being directly behind some busses is just horrible. You can get a very concentrated dose of pollutents. Diesel trains that idle can do similar things right where people are gathering. So while I don't necessarily agree with the idea that diesels increase the city wide pollution more that electrics, it probably does expose more people to high levels of emissions...not good.

Aside from smilies, there is a lot of fundamental research on this topic. Summarizing it for CleanMPG isn't on the top of my list, although perhaps it should be?

Anyway for those interested in starting down a long trail towards understanding, see if you can download the pdf from here:

http://annhyg.oxfordjournals.org/cgi/content/full/49/6/453

It's in the clear from my computer, but maybe not from yours. Another approach is to google scholar the topic and see what you can harvest for free. Read, think, decide.

I have pretty good library access over the last decade at least, and if you send me a PM with a specific request I'll try to help.

Look, this is just another one of those areas where a lot of science is 'out there', but the practicioners don't do a good job of communicating with the general public. A shame no doubt, but if you want to hit the books on your own, nobody's stopping you. Some of us are even willing to help.

DAS

DAS

I don't think anyone is suggesting diesel PM is innocuous. The point is...is diesel PM any more "dangerous" than any other form of PM2.5, especially from combustion sources in general? CARB has arbitrarily assigned a relatively high unit cancer risk to DPM and ZERO cancer risk to all other sources of PM2.5. The other 30% of the cancer risk comes from gaseous pollutants like benzene and 1,3-butadiene. So CARB is assuming all other forms of PM2.5 are innocuous, something of which I'm highly skeptical. The U.S. EPA has declined to assign a unit cancer risk to DPM due to uncertainty of how "carcinogenic" it actually is ("Hazard Assessment Document for Diesel Engine Exhaust", USEPA).

The point I'm trying to make is that some of these public officials make it sound like diesel engines are essentially the only source of PM2.5 when in actuality, they are responsible for a relatively small percentage generally speaking, even not considering the controls currently being used on on-highway, and soon off-highway, diesel engines (DPF). Most locations that are in non-attainment with the PM2.5 NAAQS would still be in non-attainment even without any diesel engine contributions to the PM2.5 inventory.

By the way, there are meteorological conditions under which receptors downwind of the power plant emission stack plume can be exposed to relatively high levels of power plant emissions in a plume dispersion scenario called "fumigation".