Smog Study of Children Yields Ominous Results
ir pollution in Southern California appears to have
subtle
long-term effects on children's lungs and may cut into girls'
breathing
capacity more than boys', according to early results from the
most
comprehensive study ever undertaken in the region.
Findings from the first year of a 10-year smog study by
USC
researchers suggest that high smog levels most markedly restrict
the wind
of girls who spend a lot of time outdoors.
Boys, on the other hand, are more likely to develop
respiratory
illnesses, as are children of either sex who live in houses with
indoor
pollution caused by pets, pests, mildew and water damage or
cigarette
smoke.
While impaired breathing capacity--reduced volume or
flow of air in
the lungs--can leave children vulnerable to respiratory disease
and
underdeveloped lungs, it is not the same as an illness like
asthma or
bronchitis. Why boys would be more prone to such diseases is
unclear,
said the researchers, who published their preliminary data today
in the
American Journal of Respiratory and Critical Care Medicine.
"It's not good news," said Helene Margolis, an
epidemiologist with the
California Air Resources Board, principal sponsor of the
$16-million
research.
The study, which began in 1993, is one of the few to
focus on
pollution's long-term effects on children--a population
considered
especially vulnerable because they spend so much time exercising
and out
of doors.
Of unprecedented scope, it involves more than 3,600
children in the
fourth, seventh and 10th grades in 12 communities in the southern
half of
the state. A wide mix of communities was selected, from those
with
relatively clean air, such as Santa Maria and Atascadero, to more
smoggy
cities like Upland and San Dimas.
The initial findings are based on questionnaires and
lung function
tests. Researchers plan in the future to also include school
absences.
Unpublished results from later years in the study, which
researchers
reported to the Air Resources Board in January, suggest that the
link
between high levels of pollution and chronic respiratory problems
holds
steady over a period of several years.
It is the promise of finding such long-term patterns
that most
intrigues pollution experts.
"That will be unique" to this study, said David Bates, a
professor
emeritus of medicine at the University of British Columbia who
has
advised USC researchers on their approach. "Everyone will be
interested
in that."
The preliminary findings of chronic lung effects on
children come in
the wake of another alarming--but unrelated--study this month
showing
that despite the Los Angeles Basin's improved air quality,
residents
still are breathing unusually dangerous levels of cancer-causing
toxins
produced mainly by motor vehicles.
The children's study, by contrast, focused on more
commonplace
byproducts of vehicles and industrial emissions--ozone,
microscopic
elements known as particulates, nitrogen dioxide and acid vapors.
The
immediate effects of such substances have been well-studied but
their
long-term impact on youngsters remains somewhat of a mystery.
Although billions of dollars are spent in this region each
year to
fight smog on the assumption that dirty air has short- and
long-term
health effects, Southern California still exceeds federal and
state
health standards for ozone and particulates, researchers said.
Yet one of the study's surprising findings was that
"ozone was not the
big hitter," said Dr. Morton Lippmann, professor of environmental
medicine at the New York University School of Medicine and a
member of
the study's advisory board. "The fine particles and acid and
nitrogen
dioxide seemed to be playing a bigger role."
That was striking because other studies have shown that
ozone--formed
when hydrocarbons and nitrogen oxides react with sunlight--is
more
clearly associated with short-term ill effects of pollution such
as
shortness of breath, chest pain and watery eyes.
Most remarkable in the first year's findings were
consistent, but as
yet unexplained, gender differences.
"There is [not just] a difference between boys and
girls; there is a
difference between the pollutants most affecting boys and girls,"
Margolis said.
Researchers clearly linked elevated pollution levels to
reduced
breathing capacity in girls. Nitrogen dioxide and particulates
apparently
were the greatest culprits, although high ozone exposure played a
significant role in girls with asthma.
Boys' breathing capacity was affected by high ozone
exposure too, but
only in those who spent a lot of time outdoors.
Boys tended to be more affected by respiratory
illnesses. In their
case, wheezing was linked to nitrogen dioxide and acid vapor.
But researchers noted that although boys initially
suffered more from
asthma, girls essentially caught up with them in that regard by
the time
they reached high school.
Researchers hope to tease out the reasons for the gender
differences
as the study progresses. Possible explanations include variations
in
boys' and girls' lung volume and airflow, growth rates and
hormonal
effects.
There were other findings that stumped researchers. For
example, they
could not explain why the incidence of excessive respiratory
disease did
not correlate with the highest levels of outdoor air pollution.
This
contrasts with the separate finding of girls' reduced lung
capacity in
highly polluted areas.
Whatever the answer, the investigators say the findings
underline the
importance of indoor pollutants such as mildew and cigarette
smoke.
Researchers argued for "a broad-based campaign to abate airborne
hazards
inside homes."
Other remaining challenges are to determine which
pollutants are
responsible for which physiological effects and how pollution
affects
asthma.
Whether reductions in lung capacity and aggravated
respiratory
illnesses will translate into lifelong health problems remains an
open
question, but such findings in the young do not bode well,
researchers
said.
"This is just a snapshot. . . . The real answer is going
to come from
finishing this study," said Dr. John M. Peters, lead author of
the
research.
Peters said the children will be followed for eight
years, with the
final two years reserved for analysis--meaning that the
fourth-graders'
health will be studied at least through high school.
Breathing Problems
Asthma is more prevalent among boys than girls until the
high school
years, according to a study of respiratory disease-prevalence
rates among
Southern California children.
Boys
Severe Grade Asthma Asthma Wheeze Bronchitis Cough Pneumonia 4 17% 9% 25% 14% 8% 2% 7 17 12 22 14 6 2 10 16 8 21 11 8 1
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