New research into the fates of infants exposed
to the smoggy air of Los Angeles provides yet
another link between air pollution and respiratory
illness and death in babies.
Only a tiny number of
infants in the study actually became ill or died
from lung-related problems, but the researchers
found the infants were more likely to do so if
they had recently been exposed to high levels
of air pollution. The babies were also at somewhat
higher risk of dying from sudden infant death
syndrome, or SIDS.
Study co-author Michelle Wilhelm said the meaning
of the research is clear. "It just adds to
the body of evidence showing that exposure to
high air pollution can lead to infant death,"
said Wilhelm, an adjunct assistant professor of
epidemiology at the University of California,
Los Angeles.
Wilhelm and her colleagues examined the records
of 19,664 infants who died between 1989 and 2000
in California's South Coast Air Basin, which includes
much of the area in and around Los Angeles, including
parts of Orange, Riverside and San Bernardino
counties. About three million babies were born
during that time in the area.
For each infant who died, the researchers found
10 living infants to use as comparisons. Then,
they examined the local levels of air pollution
for all the babies at two weeks, one month, two
months and six months before the deaths occurred.
Overall, only about two infants per 10,000 died
of respiratory-related illnesses. But according
to the researchers, the risk of respiratory death
more than doubled in infants aged 7 months to
12 months who were exposed to "high average"
levels of very small particles of pollution known
as particulate matter.
The risk of dying of SIDS went up by 15 percent
to 19 percent for every 1 part per hundred million
increase in average nitrogen dioxide levels at
two months before death.
The researchers also found that younger infants
were more likely to suffer higher rates of death
from respiratory illness if they were exposed
to higher levels of carbon monoxide two weeks
before death.
The study findings were published in the August
issue of the journal Pediatrics.
Wilhelm acknowledged that the number of deaths
from respiratory disease was still very small
despite the heavy air pollution in Los Angeles,
considered one of the smoggiest places in the
country. Still, "the potential for disease
prevention through further air pollution abatement
may be substantial since millions of infants are
exposed to similar or greater air pollution concentrations
worldwide," she said.
Dr. Rachel Moon, a pediatrician and SIDS specialist
who's familiar with the study, questioned whether
other factors could affect the respiratory health
of the infants, such as whether they spent time
outdoors or were exposed to cigarette smoke. "That
would have a huge impact on their pollution exposure,
(but) none of this was measured," said Moon,
of the Children's National Medical Center, in
Washington, D.C.
As for the seemingly higher risk of SIDS, Moon
said researchers already knew that tobacco exposure
is a major risk factor, possibly due to tiny particles
that get into the lungs.
What's next? Dr. Jonathan Grigg, professor of
pediatric respiratory and environmental medicine
at Queen Mary's School of Medicine and Dentistry
in the United Kingdom, said the current methods
of research into the effects of air pollution
on infants are "still very crude."
Ideally, he said, researchers would actually
put portable air-monitoring devices on infants
to get more reliable numbers.
