What you can’t see can hurt you: the science of tiny air pollution particles | KEYE Austin - Green Right Now
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Jul 072009

By Barbara Kessler
Green Right Now

You know those smoggy, hazy days when you look toward downtown to find the skyscrapers obscured behind a  ripply, gray veil? What horrible pollution, you think. And it may be.

But watch out, those other days when the skyscrapers blaze brightly under clear blue skies may be deceptively hazardous to your health as well, or maybe more so.

An article just out in Science News, somewhat confusingly entitled “Bad Breath” (we get it, we just have to think about it) looks at how finer particle air pollution can seep deep into our lungs and into our blood, causing harm without us “seeing” that we’re in any danger.

The gist, according to the article by Janet Raloff:

“Even on a clear, sunny day, many tens of thousands — and potentially millions — of tiny particles cloud every breath you take. Some are nearly pure carbon. But reactive metals, acids, oily hydrocarbons and other organic chemicals jacket most of these motes.”

Ok, we’ll get back to what a “mote” is in a moment. But here’s the scary part, these micro particles of “particulate matter” — identified as particles that are 2.5 micrometers in diameter or smaller — may cause  premature aging and make us more susceptible not just to respiratory illnesses, but other health conditions as well. Even when they’re at levels currently deemed safe by government standards, they are able to do damage. In fact, their very microsopic nature is why they’re so insidious.

And now for the very bad news: A lot of these tiny particles and their nano cousins, known as “ultra-fine” particles apparently come from car and truck exhaust. The EPA and others have been exploring the problem of PMs for years, but it seems the science is now homing in on exactly why and how traffic fumes hurt us, and beginning to look at those ultra fine particles that have been less studied and are, even now, difficult to track.

Our government, too, is taking more of an interest in assessing the impact of traffic on our health. Recently, the EPA announced it would look at the air outside several elementary schools that were identified in a USA Today investigation as being located in high pollution sites, mainly near factories or freeways.

This week, the Centers for Disease Control launched a website called the National Environmental Public Health Tracking Network that allows people to look at data on air pollution, and other environmental factors, in their area. You can, for instance, find the counties in your state where PM 2.5 pollution exceeded EPA standards during a selected year. And there’s information about how traffic pollution may worsen heart disease, already America’s number one killer, claiming nearly 1 million lives annually.

Meanwhile, the Science News article lists other studies looking at this emerging area of inquiry of how small particulate pollution particles alter our body’s ability to stay healthy. The studies have found that direct exposure doesn’t just aggravate lung conditions, it exacerbates inflammation throughout the human body, worsening heart and a host of other conditions.

A German study in 2007 that measured coronary artery calcification among nearly 4,500 middle-aged to elderly men and women found traffic pollution was a main culprit, according to the Science News article: “After controlling for other risk factors, that study showed that the closer people lived to a major road, the worse their atherosclerosis.”

Other studies, such as one completed in the US that released findings in March in the journal, Epidemiology, have found a similar, though not as strong, correlation between traffic exposure and arteriosclerosis.

The Science News article goes on to round up the latest research on the 2.5 micron PMs, chronicling how they worsen the situation for diabetics, cause kids more asthma attacks (you probably suspected that) and can lead to shortening of the telomeres on the ends of chromosomes, at least according to one study of traffic crossing guards. (When chromosomes have shorter end caps or telomeres, they can become less effective at replicating, which alters body chemistry in a way that weakens the immune system. Shorter telomeres, in other words, can age a person biologically.)

Some of this is new and much of it is intuitive, still it adds to the growing mound of  evidence that living near expressways or even busy surface streets can be unhealthy — something that lately appears to be getting  more research attention.

(Motes, btw, are small or tiny particles, per Websters. The term also is used to define “smart dust” — a science fictiony sort of particle that’s actually real, operates like a sensor and would take another article to explain.)

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