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 Researchers followed more than 14,000 children from birth through
ages 14 to 16 and found those born in communities with more polluted
air were more likely to develop asthma than other kids, particularly
after age 4.
While previous research has linked asthma to air pollution exposure
in early childhood, the current study offers new evidence that this
connection extends into adolescence, said lead author Dr. Ulrike
Gehring, a researcher at Utrecht University in The Netherlands.
“Exposure to air pollution is thought to cause asthma by effecting
the size and structure of the developing lung as well as the
developing immune system,” Gehring said by email. “The exact
mechanisms behind the association between air pollution exposure and
asthma in children, however, are not clear.”
To look at the link between asthma and air pollution, Gehring and
colleagues examined concentrations of nitrogen dioxide, a byproduct
of fossil fuels that can contribute to smog, and so-called
particulate matter, a mixture of solid particles and liquid droplets
that can include dust, dirt, soot and smoke.
Then, they examined questionnaire data about the children’s
respiratory health that was collected several times during
childhood. Parents were asked if kids were diagnosed with asthma,
prescribed asthma drugs or experienced wheezing. Parents were also
asked if kids had sneezing, congestion or itchy, watery eyes when
they didn’t have colds.
The study included kids from Germany, Sweden and The Netherlands.
Overall, the risk of asthma by ages 14 to 16 increased with
increasing exposure to nitrogen dioxide and particulate matter at
the birth address, but not with exposure levels for the address at
the end of the study.
Researchers didn’t find a link between air pollution exposure and
allergies.
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One limitation of the study is that researchers used air pollution
measurements from 2008 to 2010 for the entire duration of follow-up,
the researchers acknowledge in The Lancet Respiratory Medicine.
Researchers also didn’t look at air quality at school or daycare
centers, which might differ from where the children lived.
It’s also possible that children growing up near major, heavily
trafficked roadways, who are at the greatest risk for exposure to
air pollution, may differ from kids who grow up in other locations
like suburbs in other respects, such as lower socioeconomic status,
that also increase asthma risk, said Steve Georas, a researcher at
the University of Rochester Medical Center who wrote an accompanying
editorial.
Even so, the findings add to a growing body of research linking
asthma to pollution, Georas said by email.
“It is probably time to doubt no more that early life air pollution
exposure is a risk factor for asthma for some children,” Georas
said. “What we need now are more studies to understand (why) some
children are particularly susceptible to these adverse effects.”
SOURCE: http://bit.ly/1MXLSwc The Lancet Respiratory Medicine,
online November 10, 2015.
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