THE SMALLEST OF POLLUTANTS ARE LINKED TO OUTSIZE HEALTH RISKS
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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-COUNTS.HTML)
* * _LIGHT AT NIGHT: HOW TO COUNTER THE HEALTH EFFECTS_
(HTTP://HEALTH.USNEWS.COM/ARTICLES/HEALTH/CANCER/2008/02/22/LIGHT-AT-NIGHT-HOW-TO-COUNTE
R-THE-HEALTH-EFFECTS.HTML)
* * _VIDEO: AIR CARE FOR THE HEART_
(HTTP://USNEWS.FEEDROOM.COM/?FR_STORY=1D1F7C25A05B0826F219754A97CB170302970EAD&RF=BM)
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