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Diesel Exhaust Associated with Higher Heart Attack, Stroke Risk in Men

Increased roadway pollution produced by diesel fuel in vehicles is leading to a cascade of conditions that could result in heart attack or stroke, researchers suggested in the report of a small study presented at the American Heart Association’s Scientific Sessions 2007.

Researchers from the United Kingdom and Sweden found that diesel exhaust increased clot formation and blood platelet activity in healthy volunteers—which could lead to heart attack and stroke.

The study results are closely tied with previous observational and epidemiological studies showing that shortly after exposure to traffic air pollution, individuals are more likely to suffer a heart attack. This study shows that when a person is exposed to relatively high levels of diesel exhaust for a short time, the blood is more likely to clot. This could lead to a blocked vessel resulting in heart attack or stroke.

—Andrew Lucking, M.D., lead author

The double-blind, randomized, cross-over study included 20 healthy men, 21 to 44 years old. They were separately exposed to filtered air (serving as a control) and to diluted diesel exhaust at 300 micrograms per meter cubed (mcg/m3), a level comparable to curbside exposure on a busy street.

Researchers performed the exposures in a specially built diesel exposure chamber. At two hours and at six hours after exposure, researchers allowed a small amount of participants’ blood to flow through a perfusion chamber. They measured clot formation, coagulation, platelet activation and inflammatory markers after each exposure.

To measure clot formation, researchers used low and high shear rates, recreating flow conditions inside the body’s blood vessels. Compared to filtered air, breathing air with diluted diesel exhaust increased clot formation in the low shear chamber by 24.2% and the high shear chamber by 19.1%. This was seen at both two and six hours after diesel exposure.

The researchers also found an increase in platelet activation, assessed by measuring the number of platelets associated with white blood cells. Platelets play a central role in blood clotting, and when they are activated, they associate with white blood cells such as neutrophils and monocytes, Lucking said. Diluted diesel exhaust inhalation increased platelet-neutrophil aggregates from 6.5% to 9.2% and platelet-monocyte aggregates from 21% to 25% at two hours after exposure. At six hours, researchers found a trend toward platelet activation, but it was not statistically significant.

After exposure to diesel exhaust, the participants had increased levels of activated platelets that became attached to white blood cells. When activated, the platelets can stick together and form a clot.

High levels of traffic pollution are known to increase the risk of heart attack in the immediate hours or days after exposure. These findings provide a potential mechanism that could link exposure to traffic-derived air pollution with acute heart attack.

—Andrew Lucking

It’s unclear whether these findings would apply to gasoline-powered engines. Diesel engines generate many times more fine pollutant particles than comparable-sized gasoline engines.

The researchers plan to collaborate again with researchers at the University of Umea, Sweden, to test particle traps retrofitted on diesel engines to determine whether these devices are effective in reducing diesel particles.

The British Heart Foundation funded the study.

Co-authors are Magnus Lundback, M.D.; Nicholas L. Mills, M.D.; Dana Faratian, M.D.; Fleming Cassee, Ph.D.; Ken Donaldson, Ph.D.; Nicholas Boon, M.D.; Juan J. Badimon, M.D.; Thomas Sandstrom, M.D., Ph.D.; Anders Blomberg, M.D., Ph.D.; and David E. Newby, M.D., D.M., Ph.D.



Rafael Seidl

I'd be careful not to read too much into a study involving just 20 subjects, the statistical significance is not very high. Also, 300 micrograns per cubic meter is a rather high level of particulate pollution. Cairo, Beijing and Delhi - all of which are renowned for very poor air quality - averaged 150-200 micrograms per cubic meter in 2004.

However, the research is yet another data point suggesting that it's time for European cities to enforce the EU directive on PM10 immissions. They are supposed to take action if the daily average exceeds 50 micrograms per cubic meter on more than 35 days in a calendar year. This will be tightened to just 7 days in 2010. The problem is that cities can actually do little or nothing to mitigate ambient PM pollution, other than restrict traffic in some way. That carries economic costs and does not endear politicians to voters. Unsurprisingly, mayors all over Europe have been honoring the directive in the breach since it became law in January of 2005.

Fortunately, the situation will vastly improve of its own accord over the next decade as the diesel vehicle fleet churns and wall-flow DPFs become standard equipment. Some cities in Germany (e.g. Stuttgart) are looking to accelerate the process by banning high polluters (old diesels and old gasoline cars without catalytic converters) from entering the city center on days with low air quality, starting in 2008.

In addition to compliance with the EU directive, the city - home to two major auto manufacturers and several tier 1 supply chain corporations - may be hoping to boost new vehicle sales in Germany, which have been lackluster of late.


I would think the government would establish a ban on the operation of diesel engines until it can be established they are not spewing death. Are the particulate filters, akin to cigarette filters, all PR but do not result in any real reduction of health hazard?


We should ban walking around, too, because people sometimes get hit by cars and bicycles and stray golf balls and stuff and then they die.

Harvey D

Is NBK still smoking or just being funny?


Just another sign that operating ICE must be removed from large populations of humans(other animals too). More heart disease studies(like lung disease studies) will show how insidious ICE is around people. Studies of other internal organs will probably also show the detrimental effects to health of ICE.

Let's get electric energy densities up & charge times down, so we can replace ICE with EVs. May ICE die, that people will live. Long live EVs.


The report describes the test results from 'diesel' exhaust. Are/were there any variables regarding the type of diesel, e.g. petroleum vs. biodiesel, etc.? Is it the absorption of the microgram-size particles or the type of compound that has the negative health effect?


Gave up the smoke a long time ago, my friend.


Yet another reason to convert existing HDV and MDVs to CNG or LNG, where PM is far less of an issue. Electrification is great, but any transportation solution has to be affordable and effective on a Well to Wheels basis, including all the losses along the value chain and emissions from the generating mix.

Regardless of the mitigation measure, we can now add the title "Black Carbon Death Machine" that reduces social security liabilities, and accelerates Global Warming to the rap sheet for legacy diesel engines.


Well if you do not think a total ban is in order, how about diesel school buses. Using them with the knowledge we have now is akin to finger painting with lead based paint.

And a little on public bans. Managing other peoples risk is bad, like saying folks cannot smoke in their own homes, or they must wear their seat belt in their own car. But a ban something that harms others, such as legacy diesels in urban areas at least should be considered. Is the thread significant, and based on the increase in breathing disorders it sure seems to be, we should error on the side of prudence.


I'm curious about so many report about negative effect from Diesel engines. Is that a "silent" negative campaign from a party which "their business" threatened by increasing popularity of Diesel engine ?

I'm not saying that Diesel has no negative effect at all, but how about :

1. Particulate matters from gasoline engines which much smaller than Diesel PM ? (PM 2,5)

2. Praticulate matters / soot from old aircraft engines which still operated worldwide by some Low Cost carriers ?

3. Particulate matters / soot from Coal Powerplant / Coal boilers / burners, boilers / burners which using Heavy Fuel Oil ?

4. Emission from gasoline 2 stroke engines ?

5. Emission from flare gas ?

6. etc.

A fair research also have to study any negative impact from any emission sources.

Rafael Seidl

@ Van -

before you go off banning everything in sight, perhaps you should learn more about how DPFs work. Comparing them to cigarette filters is quite inappropriate.

The ambient PM10 concentration the researchers used reflects something of a worst-case scenario for individuals living in Europe today. Factory-installed wall-flow DPFs do work (>98% effective) but they've only been on the market for ~2 years. It will take at least a decade before >90% of old diesels have been consigned to the great junkyard in the sky / Africa.


Van wrote: "I would think the government would establish a ban on the operation of diesel engines until it can be established they are not spewing death. Are the particulate filters, akin to cigarette filters, all PR but do not result in any real reduction of health hazard?"

Particulate filters are the real deal, not PR. There have been plenty of high quality studies showing the incredible effectiveness of diesel particulate filters (DPFs) on particles of all sizes and of all types. A few are collected at DieselNet.

I can't think of many studies where the health effect of a DPF has been directly studied, but I know of one animal study that showed that the DPF caused a dramatic reduction in health impacts from diesel exhaust: "Effects of Low Sulfur Fuel and a Catalyzed Particle Trap on the Composition and Toxicity of Diesel Emissions" by researchers from the Lovelace Respiratory Research Institute and SKS Consulting. The abstract includes this: "Baseline DEE [diesel engine exhaust] produced statistically significant biological effects for all measured parameters. The use of low sulfur fuel and a catalyzed trap either completely or nearly eliminated the effects." Full text is available on-line for free at Environmental Health Perspectives.


Diesel particles are actually no bigger than "PM1", Motorist! Soot's finest is a continuing and continuous problem of people breathing in the streets, not one of PM10-episodes' on/off-drama and funny coloured window stickers. A problem of particle n u m b e r - concentrations and therefore n o t remotely passé in Europe's (Japan's exported) current vehicle production as Rafael once more tries to insinuate. Maybe some time "Euro-6" will actually address the problem - years from now, of course.
Clean Peugeots were available earlier than Rafael wrote. By years, of course...

But the whole amalgamation of the extensive PM10 (EU-triggered) topic and the problem of diesel particulate matter is one big unfortunate communications disaster - one of the reasons european new diesels still aren't remotely as (well) filtered as America's diesel propagandists may believe. Suffering quite an esoteric misinforming marketing here in germany for many years now. Whatever may arrive in California or else from the Krauts, does not reflect our situation, but (the value of) your own legislation over there!


Several have stated replacing ICE with EVs must be done in a cost effective manner. I agree.

While we count costs, let's not miss costs of lung disease, up-to-now unreported heart disease(as this report & others are pointing out), blood flow problems(May 1, 2007 GCC) & a bunch of late & never performed UNhealth studies on organs & bodies in general due to ICE.

Let us not forget relatives & friends unnecessarily dead of pollution related lung, heart, blood flow & other organ diseases.

Also, remember electric motors are 3 to 3+ times more efficient than ICE(so much so they don't roar, rattle, or stink), don't produce pollution at their operating(people) point, electricity is produced with less pollution & cost, & is delivered not on clogged highways & to its charging point more effectively than ICE fuels are delivered to fueling points. May ICE die that people live. Long live EVs.

Rafael Seidl

@ Mo -

engine out diesel particles have a size distribution. Most are in fact larger than 10 microns, but there is a significant portion of the particle count that is smaller. Anything less than ~7 microns can pass through the lung lining and into the bloodstream, accumulating mostly in the liver and spinal fluid. This is significant because prior to the availability of DPFs, car makers relied exclusively on ever-higher injection pressures to reduce PM10 mass, which is what vehicle certification is still based on. That has skewed the engine-out size distribution toward smaller, more dangerous particles. Note that EPA and CARB also limit PM10, simply because the traditional gravimetric measurement technique is not sensitive enough for smaller particles.

However, wall-flow - as opposed to open retrofit - DPFs do catch a high proportion of even these smallest of particles and burn them off during purge phases. The size distribution is not skewed any further in favor of smaller particles through the use of wall-flow DPFs.

As for Peugeot, they did start shipping their FAP in selected models as long ago as 2000, but it required a Cer-based ash-forming additive. Most of their competitors managed to meet Euro 4 without an expensive filter and followed suit only in 2005/2006 in response to unexpected customer demand, especially in Germany.


"Most are in fact larger than 10 microns.."
What are you going to talk about? Diesel particles' size distribution? No, plerase! They are no bigger than PM1, just as I wrote! Entire size distribution below PM1 / 1000nm, which is one micron, isn't it?
Tendency towards smaller particles is right, which is why Euro-5 won't be effective when effective, which it isn't yet.
The sentence with some PM10 being non gravimetric here doesn't really make much sense to me, so I'll skip that, just as Euro-5 should be skipped...
Now, true DPFiltration is, would and will be okay, of course. It is just not enforced until Euro-6. Best case scenario ;-(
Buyers cannot even guess or know the quality of bought filtration - if there is/ will be any at all - when buying current Euro-4. And Euro-5 won't make a difference as you know. Gravimetric limits would be perfectly fine if they guaranteed true filtration or alternative fuelling. But one cannot even rule out the possibility of the inverse:
One Euro-6 limiting number concentrations without enforcing true filtration. That's the situation in dieseling Krauts' Europe.

Roger Pham


You have been grossly mislead by the BEV advocates. With a large percentage of grid electricity coming from conventional coal-fired power plants, BEV will not offer significant emission advantage over that of ICE.

Electric cars are not 3-4x more efficient than ICE from well-to-wheel analysis. It's more like 25% more efficient than the best of gasoline-ICE today, or on par with a LDV diesel, less than a HDV diesel, and not any more efficient than an HEV, or less than a full HEV.

Diesel's PM problem can be remedied by DPF, and even better still, by conversion of diesel engine to run on NG (natural gas), which costs much less per BTU value than diesel fuel today. "Let's not throw the baby out with the bath water."

Meanwhile, taking one aspirin a day will send diesel's blood-clotting problem away! Even an 80mg baby aspirin will help, if you have a sensitive stomach. If you are not convinced, talk to you doctor.
Furthermore, many cars nowaday have built-in on-board HEPA airfiltration system that will minimize the diesel's PM problem.

Perhaps a ~$100 retrofit HEPA air filter on existing cars will do the trick for those with asthma or cardiovascular risks. This is just my idea. I'm not awared of any such existing retrofit kit.

Certainly, the diesel's PM problem is in need of a little bit of PR info like those ideas of mine! Let's not throw the baby out with the bath water!

Bud Johns

Roger, just have to say it, even though I'll bet you know. The Prius has the hepa filter. It's great. I retired and moved to the mountains of Tennessee, and there is a recirculation button on the steering wheel, (as well as the center screen) we call it the de-skunk button, because it works so good you can't smell a skunk or anything else with this turned on, OK, point is your idea isn't bad at all!


Roger...Why do I want to suck diesel fumes & take aspirins, when EVs will let me breath good air & eliminate aspirins. If you think aspirins relieve all effects ICE fumes do to the body, tooth fairies will leave dollar bills under your pillow too. Why would you dare minimize the hazards of ICE. Should babies suck diesel fumes & take baby aspirin too? Thousands of kids living & schooling near freeways ain't gettin' fixed with aspirins. Switch to EVs & lots of doctors will have fewer patients. Electric motors ARE 3 times more efficient than ICE. Electricity is delivered to charging sites(home or stations) NOT USING clogged freeways & will lessen traffic by lessening the transportation of fuels to gas stations. Electricity is delivered more efficiently than fuel. A pox on your 25%.

My northwest electric power is produced kilowatt to HP with only 4% of the pollution of ICE. With our development of further renewable electric sources that pollution is going down even more. All other grid systems can have our 4% to aim at with concerted efforts to develope renewable electric sources.


One correction to my above post. 'My northwest electric power is produced equivalent kilowatts to HP with only 4% of the pollution of ICE.'


Im so clean and perfect. Kiss my feet.



Your current mix, in the northeast, may be super clean. But most people's isn't. Moreover, while the installed base capacity in the northeast includes a lot of hydro (from Canada) and nuclear (Seabrook and Vermont Yankee), the incremental or marginal generation won't come from those sources. And if transport goes electric all of a sudden, you will need a large increment of new generation.

You can pray (to the tooth fairy, perhaps) that it will come from such wonderful and fully mature sources as wind power, but you'd be lucky, in the real world, to see it come from natural gas. You might also see it come from coal plants in the Appalachian coal belt, in which case you've made little progress at all.

Also worth noting: Gasoline distribution does not tax freeways all that much. Only the "last mile" of gasoline distribution takes place by tanker truck. Most of the long distance transportation of both crude oil and refined products takes place over dedicated networks of pipelines. In the case of refined gasoline and diesel, it arrives at local terminals, where it is then put on trucks for local distribution. When I'm stuck in traffic, I don't marvel at the huge numbers of gasoline tankers clogging up the roadways, because relative to everything else, there aren't so many.

And why you should put up with diesels and take an aspirin... Because the alternatives are hugely expensive or simply impractical. As such, they'd cause more human misery than they'd cure. Banning ICEs in favor of an idealistic embrace of EVs would, in most cases, probably improve local air quality. But, at present, they would also make motoring absurdly expensive, make the delivery of goods (such as food and novelty ice cream products) virtually impossible, and generally thrust us back into some sort of late-Victorian lifestyle. You should take an aspirin because it would ameliorate some of the effects of diesel exhaust while still allowing your food and drink to make it to your table.

Roger Pham

thanks, NBK, for an eloquent reply to litesong.

Natural gas can be used to power most diesel engines, and this will substantially reduced PM emission, also 20% less CO2 than diesel fuel. Natural gas' methane can come from a variety of feedstocks, including waste biomass pyrolysis or gasification.


Why do these discussions seem to be dominated by the extremes? Does it have to be "death to all ICE" or "take a baby aspirin"? Come on you guys, get a clue! The LDV fleet will gradually migrate to HEV, PHEV, BEV, clean diesel and probably several other things. It will be largely economically driven. Breakthroughs in various technologies will change equations, and these will be absorbed in the economic realities. BTW, Roger, the baby aspirin and hepa filter ideas (for everyone?) so that the few can drive polluting vehicles is just insulting.


Sorry people. Someone used my User Name to post on this thread.

NBK-Boston...Never have I said to ban diesels, but you've used the term multiple times already. I said lets get electric energy densities up & charge times down, & ICE will die naturally(economically). Wind turbines ARE sweeping the world. Generating power at only 3MPH, each tower supplies 750 homes. They are miraculously coming down in price & will supply many scores of thousands of Megawatts of power if not a lot more. Solar cells have busted past 40% efficiency with great versatility of placement. Electric wave & tidal generating systems are rapidly developing. Get on the band wagon & get renewables on your grid. The electric motor is so elegant, we will marvel about ancient times when we were trapped in cloudy pollutions due to ICE.

Gas indeed is often transported more than 1 mile on freeways. One gallon of gas produces 19 pounds of carbon dioxide. A total of 28 pounds of carbon dioxide is produced if you include the fuel transportation to gas stations.

George...Why do you falter at the death of ICE, when you never have cried for the millions dead due to ICE pollution.

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