The Smallest of Pollutants Are Linked to Outsize Health Risks

[Guest guest]

The Smallest of Pollutants Are Linked to Outsize Health Risks

_http://health.usnews.com/articles/health/2008/02/27/the-smallest-of-pollutant

s-are-linked-to-outsize-health-risks.html_

(http://health.usnews.com/articles/health/2008/02/27/the-smallest-of-pollutants-\

are-linked-to-outsize-health-risk

s.html)

Can steering clear of particles from traffic fumes protect the heart?

By _Adam Voiland_

(http://www.usnews.com/Topics/tag/Author/a/adam_voiland/index.html)

Posted February 27, 2008

 

 

Sitting in traffic triples a person's short-term heart-attack risk. Living

in a city with heavy air pollution such as Los Angeles is as risky for the

heart as being a former smoker. And having a house near a highway ups the risk

of hardened arteries by some 60 percent. In each case, tiny " ultrafine "

particles in the air may be a key culprit.

 

 

(USN & WR)

 

While air pollution comes in many forms, scientists are increasingly

concerned about its most minute constituents—virus-size particles produced by

combustion. These ultrafines, which measure no more than 0.1 micrometer in

diameter, are ubiquitous near roadways and are emerging as one of the most

dangerous

components of air pollution, which kills an estimated 60,000-plus Americans a

year. That's more than the number killed annually by automobile accidents.

The tiny particles are worrisome for several reasons. For one, they tend to

be rich in potentially toxic organic compounds and other reactive chemicals.

Their size, moreover, allows them to travel deep into the lungs, lodge there

for long periods, and stress the body in a variety of ways, researchers

theorize. They may even slip into the bloodstream, where they can do further

damage. In comparison, so-called fine particulates, which can be up to 25 times

wider than ultrafines, are snared more easily by protective hairlike structures

in the nose and throat. Not that fine particulates are benign: Last year, a

study of older women in the New England Journal of Medicine linked a

10-microgram-per-cubic-meter increase in fine particulate

pollution—approximately the

difference between Pittsburgh and cleaner Anchorage—to a 76 percent increase

in the cardiovascular death rate.

More recent data seem to confirm researchers' suspicions that smaller

particles are even worse. With Environmental Protection Agency funding, a team

co-led by Jesus Araujo, an environmental cardiologist at UCLA, zoomed in on the

ultrafines and found that mice exposed to those particles developed more

atherosclerotic plaque than mice breathing fine particulates only—and did so

faster. " Much, much faster, " says Araujo. In addition, HDL, or good cholesterol,

didn't work as well in ultrafine-exposed animals, Araujo's team will report in

the March 14 Circulation Research. Other recent experiments have found

troubling cardiovascular changes in human volunteers following exposure to

ultrafines.

Such findings are bad news for people with heavy exposure to traffic. Diesel

vehicles are particularly potent sources of both fine and ultrafine

particles, and their fumes, recent studies show, have adverse effects on the

heart.

European researchers found, for example, that exercising men who inhaled fresh

diesel fumes at levels that can occur near major roads experienced rapid

reduction in blood flow to the heart and a one-third drop in a protective

protein that prevents dangerous clotting. " The effect was about the same as what

we

see with secondhand smoke, " explains Nicholas Mills, the University of

Edinburgh cardiologist who led the research.

At risk. The elderly, young children, and those with pulmonary and

cardiovascular problems are most at risk from particulate air pollution.

However,

particles affect everybody. Recent Taiwanese research shows, for example, that

inflammation, oxidative stress, and other cardiovascular warning signs are

detectable among urban teens breathing polluted air as well.

While fine particulate matter and certain smog-generating emissions are

regulated, ultrafine particles are not. " There's no doubt particulate matter is

the elephant in the room, " says Dan Costa, the director of the Environmental

Protection Agency's air research program. Since 1997, the agency has been

cracking down on fine particulates, and their levels have generally been

falling

nationwide. A new rule, phased in last year, requires trucks to use

cleaner-burning diesel fuel and should help reduce both fines and ultrafines.

But it

may be a decade, Costa says, before scientists amass enough evidence on

ultrafines to justify directly limiting them.

A third to a half of ultrafine exposure comes from driving. " If you have

otherwise healthy habits and don't smoke, driving to work is probably the most

unhealthy part of your day, " says Scott Fruin, an environmental scientist at

the University of Southern California. The tiny particles can also slip into

homes, especially those near busy roads. Cooking with a poorly ventilated

stove can be another source of exposure to ultrafines, he says. Some fireplaces

also generate particulates. However, so-called HEPA filters can help clear

indoor air of particulates, including ultrafines.

Avoiding exposure. Exercising near traffic increases one's exposure, since

heavy breathing draws particles deep into the body. Murray Mittleman, a

cardiologist at Harvard University, suggests that people—especially those

with

heart conditions—try to exercise away from major roadways. Masks probably

won't

have much of an effect on the tiny ultrafines, says Fruin, but might stop

larger particles. (Some U.S. Olympians, in fact, have been advised to wear face

masks in heavily polluted Beijing.) Two government websites, _airnow.gov_

(http://www.airnow.gov/) and _epa.gov/airtrends_

(http://www.epa.gov/airtrends/)

, can help people plan outdoor activities.

Still, there's no reason to live in complete fear of particulates; the risk

for any individual remains quite small. That tripling of heart attack risk

due to traffic exposure, for example, sounds frightening but is similar to the

increased short-term risk posed by exercise or even sexual activity, says

Robert Brook, a University of Michigan cardiologist. " The absolute

risk—meaning

the risk you have every single time you are exposed to air pollution,

exercise, or have intercourse—is still very, very low, " he says. " But when

you

multiply that by the tens of millions of people being exposed to polluted air

all

of the time, you end up getting large numbers of people who are affected. "

Araujo, for one, isn't taking any chances. He used to bike frequently in

heavy traffic. However, after seeing what happened to his mice, he says: " You

won't find me stuck behind bus tailpipes anymore. "

 

 

Related News

* _Smallest Air Pollution Particles Hurt Heart Most_

(http://health.usnews.com/usnews/health/healthday/080119/smallest-air-pollution-\

particles-hurt-he

art-most.htm)

* * _Air Pollution Kicks Men Where it Counts_

(http://www.usnews.com/blogs/on-men/2008/2/22/air-pollution-kicks-men-where-it-c\

ounts.html)

* * _Light at Night: How to Counter the Health Effects_

(http://health.usnews.com/articles/health/cancer/2008/02/22/light-at-night-how-t\

o-counte

r-the-health-effects.html)

* * _Video: Air Care for the Heart_

(http://usnews.feedroom.com/?fr_story=1d1f7c25a05b0826f219754a97cb170302970ead & r\

f=bm)