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UC Davis study identifies toxicity of particulate matter from specific sources

The California Air Resources Board and the Electric Power Research Institute (EPRI) released a report they commissioned by investigators at the University of California, Davis that looks at how to distinguish health effects caused by different types of fine and ultrafine airborne particulate matter (PM) from different sources. This is among the first studies to examine the toxicology of particles according to their source origin. Previous research has linked fine and ultrafine particles to asthma, heart disease and other adverse health effects.

These particles—produced by emissions from many different sources, including traffic, industrial processes, wood-burning fireplaces and gas- and coal-fired power plants—combine in the atmosphere and are affected by sunlight and other meteorological variables. National Ambient Air Quality Standards do not distinguish between these source since they are based solely on mass in given particle size rang. Further, the mixing makes it difficult to determine which compounds in particulate matter may be responsible for specific health effects.

The research was conducted by Dr. Anthony Wexler, director of the Air Quality Research Center at the University of California, Davis. Dr. Wexler used a single particle mass spectrometer and ten particle samplers to capture ambient particles. He then developed novel methods to extract particulate matter from the filter and polyurethane foam substrates, so that (a) as much of the particulate matter was extracted from the substrates and (b) hydroscopic and hydrophobic compounds in the particulate matter were extracted evenly.

Laboratory mice were exposed to the separated particles, and their responses were monitored for signs of toxicity by Dr. Kent Pinkerton, a professor of pediatrics at the UC Davis School of Medicine.

The analysis showed different levels of toxicity for different PM samples, associated with a variety of sources, such as traffic and wood smoke. Most of the toxicity was associated with automobile and cooking sources in both seasons while in the winter toxicity was also associated with secondary compounds. Ultrafine particles were more potent inducers of inflammatory markers and cell death than larger particles.

Broadly, the study found that:

  • Based on particle size, UF PM was a more potent inducer of inflammatory and cytotoxic response compared to SMF PM on a per mass basis.

  • For pulmonary inflammation and cytotoxicity, samples containing PM from vehicular sources or metals had the high biological response for summer samples, while PM from vehicular sources, regional processes background, and nighttime inversions had the highest response for winter samples.

  • In general, the same PM sample produced greater inflammatory and cytotoxic responses in lung samples than in the blood samples under the conditions used in this study.

  • Analysis of systemic inflammation did not reveal major differences between the collected samples.

Direct toxicity testing of source-oriented PM can increase understanding of the associations between adverse health effects and PM exposure. Different source-oriented and size-resolved samples of sub-micron particulate matter elicited differing levels of response in an array of toxicity measures, supporting the founding hypothesis for this study that different sources and combinations of sources of particulate matter have different levels of toxicity. The unanticipated result was that the sources were toxic in different ways. Ultimately, these advances will contribute to more specific regulations of particulate matter in order to provide greater protection of human health.

—Wexler and Pinkerton

EPRI’s air quality research team of Dr. Annette Rohr, Dr. Stephanie Shaw and Dr. Eladio Knipping, helped design the study, as well as reviewed the methods used and results from the ambient measurements and toxicity responses.




Will groups associated with major polluters, responsible for particulate matter emission, play and active role into this research? If so, they will certainly try to water down the findings and/or pay a few researchers to do it??


Who is paying you? Are you able to read a published paper and understand it? Otherwise you should write to Anthony S. Wexler and Kent Pinkerton and tell them why their study is flawed. Have you ever lived in California?


Nice study...but only if some good actually comes out of it. Meanwhile, the UN says approximately 10,000 people died today due to particulates from burning fuels.

Diesel exhaust was only recently put on the "known human carcinogen" list by the UN. It took 70 years to figure that out?

By the time another 10 years goes by of talking and studying, more people will die from particulates than all the world wars combined.

It's time for mankind to simply stop the burning. New technologies are waiting in the wings.


".. how to distinguish health effects caused by different types of fine and ultrafine airborne particulate matter (PM) from different sources."

Positively identifying the source corporation of the killing particles in the lungs of a dying victim is like fingerprints on the murder weapon(in a video).


A higher Canadian court has very recently ruled in favor of a miner claiming that exhaust from the diesel powered mining machine gave him lung cancer.

Unfortunately, the miner had already died from lung cancer when the verdict came out. His widow will receive the financial benefits.

The ruling will be very useful for other miners.

Mining Cos will have to use much lower pollution hybrid or electric machines in the future.

@ LanceK:

We are too often mislead by biased studies, partly or fully paid by the polluters or their paid lobbies. It is nothing new but it is more and more difficult to know what is the truth or ....?

Kit P

Once again kelly demonstrates his ability to slander is not impaired by the facts of the research.

“source corporation ”

That would be people driving home from work and cooking dinner.

“dying victim ”

In this case the victims were mice and there was no dying going on.

There is nothing wrong with research. Like most research it is a step to the next step. When it comes to reducing pollution the systematic approach is to identify the source. Then you have to engineer solutions society will accept.


Actually Kit, like my fellow Canadian Harvey, I've learn to be skeptial as a default position. Any single study can be biased, for or against, so it's best to take the measure of ALL the studies on a subject and go with the side that has consensus.

Case in point of a biased study;


Sorry Kit, I should have said "LanceK."


@Kit P, my point went over your head again, but not that of your masters.

@HarveyD, thanks for showing the Canadian court confirming my point.

@ai vin, thanks for another fine 'studies' link;

"Male and female smokers lose an average of 13.2 and 14.5 years of life, respectively."[23]wiki

"the estimated death toll to about 900,000 for the first 15 years after Chernobyl."

Isn't it interesting how mass murderers always need more studies of their work.

For ~100 years, what US "recruit" had not heard, "Smoke um if you got um, police um if you don't" from his drill sergeant.

Legally settled, the recuits the government started smoking, now veterans, should now each receive(or their survivors) $millions in "Male and female smokers lose an average of 13.2 and 14.5 years of life, respectively." settlements.

Kit P

“I've learn to be skeptial ”

I am betting that I am the only person posting here that actually opened the study and read it except maybe Lance.

“Have you ever lived in California? ”

Yes, and the report finding make a lot of sense. I also took environment classes at UC Davis. I have a lot of respect for EPRI. The power industry pays EPRI to do good research to help us solve problems. While being skeptical is fine, maybe you should on the other hand call professionals unethical unless you have some evident.

I have a lot of evidence that most who post here are more gullible and less skeptical. For example from AV's link,

“A major 40-year study on asbestos safety ...”

This article is a cheap shot hit piece written by a journalist.

“health activist and longtime industry critic ”

I am betting this jerk never had to worry about fighting a fire in a power plant. Asbestos should not have been banned but regulated for essential uses.

“No safe level of exposure”

Just about everyone my age who worked in the navy or power industry has been exposed to asbestos without being harmed. If fact, just about everyone in an industrialized society has been exposed.

It is the dose that make the poison.

Harvey and AV need to be a little bit more skeptical of what they learn from journalist and maybe stop being such fear mongers.

Kit P

“Smoke um if you got um ”

I think it would be hard to get any reasonable person to equate allowing a smoke breaks with mass murder. I was one of the few in my boot camp company who did not smoke. The smokers were there from day one but I never had to police their butts. Maybe sailors are smarter than soldiers, we had respectable to put cigarettes.

It has been common knowledge that smoking 'contributes' to poor health. If succumbed to peer pressure and started smoking, you do not want me on your jury when you are blaming someone else for your stupidity.

“estimated death toll to about 900,000 ”

The actually death toll is around 50. Those who died of radiation poisoning are easy identify. Young children who died of thyroid cancer is a second group. Very few of those in this group.

If you choose to live a destructive lifestyle by eating too much, smoking too much, drinking too, and using recreational drug; the responsibility is yours.

I have worked for both the navy and corporations for more than 40 years. I have always been provided the tools to protect myself, those who worked around me, and the people who live around where I work.

Some like kelly think I should live my life based on their stupidity.

Clearly Nazis Germany and the USSR practiced mass murder. The evil empire had a terrible record for industrial safety and environmental protection.

So what does that have to with a scientific study done in California? When presented with an example of doing something right, the usual suspects start presenting example of old stuff. In other words they do not learn. Science is about moving forward.


@Kit P, like your POTU hero - your struggling for a 20% correct reality.

Your "asbestos - no problem" is absurd because $20 billion asbestos damage settlement funds were established from guilty legal judgments. It's even on TV, but I didn't realize:

"Symptoms or signs of mesothelioma may not appear until 20 to 50 years (or more) after exposure to asbestos."

"(Steve) McQueen .. may have been exposed to asbestos while serving with the U.S. Marines as a young adult—asbestos was then commonly used to insulate ships' piping—or from its use as an insulating material in automobile racing suits (McQueen was an avid racing driver and fan).[51]" wiki,

"I was one of the few in my boot camp company who did not smoke." Think about what you wrote. "one of the few.. confirms you felt the government pressure to 'start smoking' a dangerous addictive drug.

You do understand that if you kill a terminally ill person - even shortening their life by ONE DAY - it's legally murder.

"Male and female smokers lose an average of 13.2 and 14.5 years of life" Again, in your mind - no problem..

Get a checkup. Some of the mental health effects also take decades to present.


@Kit P:

Have you always been 500% pro-Industries regardless of the harmful products they sell?

The world is progressively learning about the 1001 harmful industrial products to be curtailed soon for our own well being. Tobacco and Asbestos were only two of the very harmful ones to be dealt with.

The new industrial energy sweet drinks, over-loaded with habit forming nicotine and caffeine have already killed dozens in USA and Canada and are making our kid fat, obese and sick. It is time to do something about it?

There are 1001+ other similar products on the market.

PS: Our last Provincial Government promised/gave $58,000,000 to our remaining asbestos mine in the last few days of its not too honest reign in an attempt to stay in power. The new Government will have to spend a few rare $$M to cancel that impossible-illegal deal.

We have to collectively wake up and ban those harmful products regardless of what the industry well paid lobbies are saying.


Did you know that (in Canada) we give $$B/year to Oil polluting Industries but not a single dollar to clean Hydro Electricity producers. In USA, they support so called 'clean' coal power plants with $$B in subsidies and hand outs but very little to clean e-power plants.

Kit P

“harmful products ”

I happen to think that asbestos is a beneficial product. There are many beneficial uses which is why it was so widely used. So how harmful is it based on kelly's favorite reference WIKI.

“mesothelioma is still a relatively rare cancer ....peaked at 15 per 1,000,000 in the United States ”

One of the difficulties in finding contributing factors for a rare cancer is the period of latency. Steve McQueen for example died 30 years after his acute exposure. Hindsight is great. Today we would not use such a beneficial product because the risk of harmful effects are too great.

“"asbestos - no problem" ”

Of course I did not say that and think that asbestos workers do deserve to be compensated for the suffering that came there way.

“it's legally murder ”

Actually it would be suicide. It is that the period of latency thing again. Peer pressure is stronger that government warnings about long term health effects. The odds seem pretty good for avoiding lung cancer according to wiki.

“a lung cancer incidence of over 1,000 per 1,000,000. ”

While I can not see any benefits to smoking you will have to ask smokers. Again from wiki.

“The most significant risk factor for developing cancer is old age.”

Clearly the benefit of getting older is that it is the beats the alternative. How many days will a filet mignon and a nice red coat me? Surely kelly and Harvey will think that evil feedlot operators and Spanish vintners are murderous criminals. I would like to thank them for their hard work that helped make my long life more enjoyable.


"“"asbestos - no problem" ”

Of course I did not say that and think that asbestos workers do deserve to be compensated for the suffering that came there way."

If you think there should be compensation for suffering - support it.

Corporations know which of their products produced are excessively lethal, but sell lethal products for profit anyway.

Tobacco Inc. knew tobacco kills, with stacks of research proving it - but advertised the opposite - murdering millions. Asbestos, nuclear, auto makers - battling $10 seat belts, pollution control, safety - follow(ed) the same pattern and blood.


One can wonder who pays KitP to support and promote the use of Tobacco, Asbestos, Energy sweet drinks, Junk foods, Plastic bottles, ICEs, Coal fired power plants, Pesticides, Tar Sands operations, etc, etc.

Is it possible for the same person to support so many harmful pollution sources?


"It is difficult to get a man to understand something when his salary depends upon his not understanding it." - Upton Sinclair


Well said Upton Sinclair. That's probably the reason why a few posters repeatedly support the use of fossil fuel vehicles, coal fired power stations over clean electrified vehicles and clean electricity production?

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