November 22, 2011
Tailpipe Exhaust Damages Brain Cells

A Wall Street Journal article reports on accumulating evidence that particulates from car and truck exhausts damage brain cells.

As roadways choke on traffic, researchers suspect that the tailpipe exhaust from cars and trucks—especially tiny carbon particles already implicated in heart disease, cancer and respiratory ailments—may also injure brain cells and synapses key to learning and memory.

This is an argument for accelerating the development of batteries for electric vehicles. It is also an argument for working from home or living closer to work to reduce the time you spend breathing vehicle exhaust in your car. Ditto for driving to work very early.

Parenthetically, the amount of smoke I've seen gushing out of a diesel commuter passenger train is disgusting. Are train emissions regulations less strict than truck emissions regulations?

One problem with diesel trucks: they last a long time. So while in recent years emissions regulations for trucks have gotten much tighter we are going to have to wait decades for the older and higher polluting trucks to wear out. Outfitting the older trucks with newer emissions control equipment would be money well spent.

One thing you can do: See if your car has a cabin air filter (note, that PDF is only thru 2007 models and might not be complete) and replace it when dirty. Some filters are easy to replace, others require skill and time. Here's a Prius owners chat on cabin air filter replacement. Note that these filters are not HEPA level. So they are limited but better than nothing.

You can find portable HEPA filters that can plug into ashtray power. If you don't mind basically giving up a seat for an air filter you can get more benefit. But I've read online discussions about the rate of turn-over of cabin air per hour (Air Changes per Hour or ACH) where one participant says the portable HEPA filters can't pump air thru fast enough to keep up in the rate at which air comes in from the outside. But when stuck in traffic the air comes in more slowly and at a lower air quality. Such a filter might work better when it is most needed.

Does any OEM offer a HEPA filter option or some other claim to better air quality thru filtering?

Share |      Randall Parker, 2011 November 22 08:39 PM  Health Pollution Harm

Rick Z said at November 23, 2011 4:15 AM:

I used to get migraines from Diesel exhaust in the 70's and 80's. I'm not sure what caused an improvement in my symptoms in the 90's and early 00's, but I certainly noticed fewer semis belching large clouds of soot during heavy load operation. The newer engines and exhaust treatments certainly help, but I still try to avoid exposure to them. This was actually the main driver for avoiding the higher end models the last time I was car shopping--only the low end models had a reliable air recirculation switch for when I got stuck near a stinker.

Since the exhaust after-treatment is performed by active devices with engine control interactions (and the engines were redesigned to emit fewer nasties for the after-treatment to deal with), I don't see how it could be remotely cost-effective to retrofit older cars and trucks to improve their emissions. It would be less expensive to replace the cars and trucks than to redesign and retrofit their Powertrains. Trains may be a different matter given their much higher per unit replacement costs, presumably lower engine design churn, and the limited number of operators who are more beholden to community interests. You could attempt to legislate the older trucks out of your region, but that is likely to just ship many of them for use in other regions. On a similar tack, I've noticed some municipalities insert clauses into construction contracts to require the use of less polluting equipment. I especially appreciate this when I'm stuck in slow moving traffic in a construction zone--some of that old equipment was worse than the semis in the 70's!

The cabin air filter isn't going to do much to filter out particulates. The particulates are just too small. Still, it's a good reminder to check it so that it can be more effective filtering out what it can help with. I haven't checked my 2006 yet and I'm sure it is due.

On a happy note, I've just recently moved to drop my moderate 26 mile commute down to an insane 1.3 miles. It may be difficult to parse out the benefits of the lower emissions exposure, the lower commute stress, the lower construction/traffic/weather delay risk exposure, the gas savings, the lower carbon footprint, the increase in time for more fruitful endeavors, and the general self-righteousness, but I'm certainly digging it! I have a new bike on order for the fair weather days, not that we get as many of those in Michigan as you get in SoCal.

bbartlog said at November 23, 2011 6:35 AM:

There is some regulation of diesel locomotive exhaust, but I don't know the details. Back in 1997 I visited the GE diesel engine plant in Erie in order to do some CAD work on an engine test cell, which (the cell, not my work) included a vent to capture and measure particulate emissions. I think there was some financial incentive to minimize them, but not a hard cap. Things may have changed in the fifteen years since. Twenty trains a day run by my house and to be honest I can't recall seeing a single plume of particulate smoke from the diesels. They may have gotten pretty good at capturing and reburning the soot.
In any case, if the problem is proximate exposure to particulates then sources that are close to a lot of people (like semi trucks) should be more regulated than something like a train, that spends most of its time far from people.

Lou Pagnucco said at November 23, 2011 7:51 AM:

A case of visible, concentrated benefit (to industries) versus invisible, diffuse harm (to public).

It's easy to focus on the negatives - possible harm to brain, lungs, heart, liver.

Maybe, it's better to focus on the absence of damage to the digestive, skeletal or endocrine systems.

PacRim Jim said at November 23, 2011 2:49 PM:

Good things we have lots of brain cells.
FYI, as I recall, the density of exhaust particulates decreases in proportion to the square of the distance from the highway, so a house 100 m away would have one-fourth the density of a house 50 m away.

PacRim Jim said at November 23, 2011 2:51 PM:

Forgot to mention that diesel engines expel particles much smaller than those of gasoline engines, so the particles travel much deeper into the lungs, remain longer, and cause more damage.

Nick G said at November 24, 2011 10:28 AM:

There are federal grants for fleet diesel retro-fits. I have one large client that just finished the process - they're very happy.

JAY said at November 24, 2011 11:56 AM:

Rare metals and chemicals in batteries are far more dangerous.

Randall Parker said at November 24, 2011 2:45 PM:

Rick Z,

Thanks for your informed comments. I am not proposing retrofitting up to today's emissions standards. I am guessing retrofits could bring substantial reductions in total emissions even while not reaching today's standards. However, perhaps it is too late to matter. I thought long haul trucks last for decades. But this article puts category 8 truck lifespan at 10 years and 1 million miles.

Move to shorten commute: Highly excellent. I've got a very short commute too and in the morning it is on mostly empty roads.

At home I just got a HEPA filter unit too. Figure I'm cutting my exposure to carcinogens a bit with it.


Any idea on lifespan of these trucks?

Ronald Brak said at November 24, 2011 4:09 PM:

Jay, I have a feeling that, generally speaking, things in your lungs are more dangerous than things in batteries.

Bartholamew Jenkins said at November 24, 2011 4:47 PM:

I use a carbon filter when I mount my motorcycle. Hopefully I'm saved.

Nick G said at November 24, 2011 7:38 PM:

I think median age of the fleet is just under 10 years, so lifespan would be in the upper teens. This is road maintenance and construction equipment.

Andrew said at November 25, 2011 10:58 AM:

Hey, I thought it was lead paint, fat, salt, transfats, aluminum, asbestos, beer, whiskey, good scotch, wine, psycho women, fly ash, arsenic in fish, vitamin abcdefghijklmnopqrstuvwxyz and demoncraps that did that!

Good thing we have ethanol now! No, wait.....

argasdoc said at November 25, 2011 11:12 AM:

Key sentence in article: "So far, the evidence is largely circumstantial". Similar to the AGW crowd that ran with "science" that was not rigorously challenged/studied, caution in chasing down every rabbit hole study that is based on circumstantial, weak correlations. Another red flag for me with this study is the correlation that they are drawing with autism-remember the damage caused by the weak correlation with vaccines??
Alan Reitz

Shannon Love said at November 25, 2011 11:55 AM:

Yeah, this has all the hallmarks of a politically motivated proto-hysteria based on extrapolating from the far-end of the probability distribution from multiple unrelated studies. Anyone who claims to find a correlation with autism is instantly suspect because there is no objective test for autism. The supposed "explosion" in autism rates is solely a function of shifting the same individuals from the "mentally retarded" column and into the autism column. In other words, only the labels have changed. Correlation of autism with local environment most likely just reflect local changes in diagnostic criteria for autism.

However, even if there is a problem with exhaust, the true source of the problem isn't' the engines or their emissions. The real problem is dense traffic and/or traffic jams. Both those factors are primarily caused by a low ratio of roads to vehicles and the primary cause of that problem is pseudo-environmentalism have systematically block road construction in community after community. As communities grow, the road construction must keep pace or you get dangerous congestion. It's just that simple. You could have a traffic jams in a small town out in the dessert if you don't build enough roads.

You've got to admire the cleverness of the scam. Cars are bad so we should build fewer roads but now we have traffic jams that cause people to breath a lot exhaust which means cars are bad so we should build fewer roads.

John Pearson said at November 25, 2011 12:33 PM:

It's a good thing auto manufacturers have reduced exhaust emissions by more than 95%(!) since 1970. This information is readily available from the EPA:

I guess everyone over the age of 41 should be considered mentally suspect since they were exposed to 25X more toxic tailpipe exhaust. New theory: automotive exhaust causes Alzheimer's, arthritis, congestive heart disease and incontinence.

Damn you, Government Motors!

Ronnie Schreiber said at November 25, 2011 12:42 PM:

My mom's 87. Today there are millions of people living well into their 80s and they are living well, in much better health than the few members of their parents' generation to have lived that long. The people alive today in their 80s were exposed to much higher levels of pollution from cars, trucks and industrial sources than we are exposed to today. They've also been eating fruits and vegetables grown with the assistance of all sorts of pesticides, herbicides and other agricultural chemicals. And after being exposed to all those environmental factors, they're still living longer and healthier than any humans in history.

So maybe the conclusion is that all that industry and technology and cheap energy from fossil fuels is good for us. The net result is a benefit.

Ronnie Schreiber
Cars In Depth

AD said at November 25, 2011 12:52 PM:

But Ronnie, your conclusion will not generate any funding for the researchers who have to pay-off their student loans.

bbartlog said at November 25, 2011 6:36 PM:

@Ronnie: the fact that we are, on net, better off, does not mean that some of the things you mention aren't bad for us. Who knows whether we wouldn't be living even longer if we had stricter environmental laws?
I am also curious whether you have a source for the claim that those who live into their 80s now are in better health than those who did so in generations prior. Look at the chart of life expectancy here: . Life expectancy at birth has grown by leaps and bounds since 1900 (from 50 to 77 or so). Life expectancy for those who are 65, however, has only improved less: from twelve years (77) to eighteen (83). Meanwhile, the life expectancy for those who make it to 85 is an almost flat line, going from five years in 1900 to seven years a century later. Given that we have vastly more medical technology available to treat these 85+ year olds, I would claim that the few who made it into their 80s a hundred years ago were probably healthier specimens than those who reach that age today.

Zog said at November 27, 2011 12:27 PM:

The fact that walking along a busy road the air smells and feels horrible should make it obvious that it is bad for you. Why would man have evolved this response otherwise?

people should be aware however that the worst air pollution a typical american encounters is from fireplaces, coal BBQs, campfires, and poorly ventalated kitchens.

bbartlog, thanks for the interesting info on life expectancy.

Jeff Carter said at October 8, 2014 2:05 AM:

Hmmm. Actually pretty interesting.

Jeff Carter said at October 8, 2014 2:06 AM:

Hmmm. Actually pretty interesting.

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