Traffic pollution from freeways may stunt development of the
lungs in children aged 10 to 18, according to a study by researchers from the
University of Southern California.
Dr. W. James Gauderman and colleagues from the USC and other
institutions found that development of the lungs in children who lived within
500 meters or one third of a mile of a freeway were significantly retarded by traffic
pollution compared to those who lived three times farther away from a freeway.
Previous studies have shown that children living near
highways are more likely to develop respiratory problems such as asthma.
The current study, published on
January 26, 2007 in
Early Online Publication
meant to establish an association between residential exposure to freeways and
other major roads and 8-year lung function growth.
Such an association between long exposure to car and truck
exhaust and the growth of the lungs and their capacity has been unknown until
the current study although it is well known the car exhausts are toxic.
In the study, Dr. Gauderman and colleagues followed 3,677
children starting at age 10 from 12 southern
communities including the cities of Alpine,
Beach, Mira Loma,
The residential areas represented a wide
range in regional air quality. They measured lung function in each child every
year for eight years.
The researchers considered the range of age because lung
development is fastest and more susceptible to environmental risks during the
period between age 10 and 18.
At age 18,
the lungs get mature and stop development.
Children who lived within 500 meters of a freeway or
motorway had substantial deficits in eight-year growth of forced expiratory
volume in 1 s (FEV1), 81 ML less than that in children who lived at least 1,500
meters away from a freeway, the researchers found.
Likewise, children who lived closer to freeways had a smaller
maximum midexpiratory flow rate (MMEF), 127ML/s less than that for children who
lived farther away from freeways.
Study data showed that both local exposures to freeways and
regional air pollution had detrimental, yet independent effects on
Previous studies have
demonstrated a link between regional air quality and lung function growth.
In addition, at age 18, children who lived within 500 m of a
freeway had pronounced deficits in attained lung function with mean
percent-predicted 97·0 percent for FEV1 relative to that for those who lived 1,500
m or farther away from a freeway.
was reduced to 93.4 percent.
"Otherwise-healthy children who were non-asthmatic and
non-smokers also experienced a significant decrease in lung function from
traffic pollution," said Dr. Gauderman. "This suggests that all
children, not just susceptible subgroups, are potentially affected by traffic
Researchers writes in their report that "local exposure
to traffic on a freeway has adverse effects on children's lung development,
which are independent of regional air quality, and which could result in
important deficits in attained lung function in later life."
It remains unknown how these deficits in the lung functions
would impact the lung functions after age of 18 years.
It is also unknown how traffic population would
affect the lung development in children younger than 10 years.
But "someone suffering a pollution-related deficit in
lung function as a child will probably have less than healthy lungs all of his
or her life," said Dr. Gauderman. "And poor lung function in later
adult life is known to be a major risk factor for respiratory and
"This study shows there are health effects from
childhood exposure to traffic exhaust that can last a lifetime," said
David A. Schwartz, M.D., Director of the National Institute of Environmental
Health Sciences (NIEHS).
The current study did not seek to explain why lung function
was comprised in the children who lived in the vicinity of a freeway although
the researchers claimed that traffic pollution was responsible.
In an early study, Dr. Jonathan Grigg and colleagues from
United Kingdom found that tiny
carbon particles generated from incomplete fuel combustion in traffic fumes
could get into children's airways in the lungs, diminishing their lung
They found that every one micrometer-squired increase of
carbon content in children lungs would result in 13 percent reduction in forced
vital capacity (FVC), 17 percent reduction in forced expiratory volume in one
second (FEV1), and 35 percent reduction in the forced expiratory flow.
The study published in the July 6 2006 issue of The New England
Journal of Medicine involved 114 healthy children from Leicester, a city in
researchers examined valid sputum (mucous) samples from 64 children and
assessed their lung function.
New reported cited Grigg as stressing that the damage to
children's lungs is cumulative. According to the authors, the adverse effect of
particle pollution on lung function growth was small, but cumulative. Long term
exposure can exert a large negative effect.
The state of
in October, 2004 issued a fact sheet titled
Air Pollution from Nearby Traffic and Children’s Health
to remind parents and schools of the danger of traffic pollution to children’s
health. Although the state did not realize at the time that living near
freeways may harm development of the lungs in children, tips offered on how to
prevent traffic pollution should still valid.
To minimize children’s exposure to air or traffic pollution,
Drivers never leave your car idling in the garage.
Children should avoid standing near idling motor vehicles when
Choose streets with less traffic if possible if you have to walk.
Close windows and doors during peak traffic hours and place the
air conditioner setting on “re-circulate” if you live near freeways or roads
with heavy traffic.
Try not to follow closely behind cars, trucks and buses that
have visible smoke rising from the exhaust pipe when you drive.
Carpool and use alternative transportation when possible.
Buy a car with low exhaust emissions when you buy a new car.
The current study was funded by the California Air Resources Board, the
National Institute of Environmental Health Sciences, the U.S. Environmental
Protection Agency, the National Heart, Lung and Blood Institute and the
W. James Gauderman, Hita Vora, Rob McConnell, Kiros Berhane, Frank
Gilliland, Duncan Thomas, Fred Lurmann, Edward Avol, Nino Kunzli, Michael
Jerrett and John Peters, "Effect of exposure to traffic on lung
development from 10 to 18 years of age: a cohort study," The Lancet,
Volume 368, February 2007.