I knew it! (Auto exhaust and asthma)
- The epidemiology of asthma has always struck me as pointing to
automobile exhaust as a major culprit. Although I was spared the curse
of asthma, I did develop severe respiratory allergies when I was six,
but only after my family moved from a quiet residential side street to
a house located on the main highway through town (a street where
trucks and cars ran constantly day and night).
However, articles about asthma typically ignore or give short shrift
to the idea. Typically, writers talk about city versus country,
exposure to animals in child, developed versus undeveloped countries,
or excessive cleanliness in the modern world.
Now here's a causal link to car exhaust.
POLLUTION LINK TO ASTHMA IN THE WOMB
Traffic pollution causes genetic changes in the womb which increase a
child's risk of developing asthma, research suggests.
A study of umbilical cord blood from 56 children found "reprogramming"
of a gene associated with exposure to compounds in traffic fumes.
The gene was associated with asthma symptoms at age five, the
researchers reported in the PLoS ONE journal.
It is the first time pollution has been shown to influence genes,
In the study, researchers looked at a gene called ACSL3, which is
expressed in the lung.
We know that children living in polluted areas have a higher incidence
of asthma but what we didn't know was it was affecting a gene
Dr Keith Prowse, British Lung Foundation
They also recorded the mothers' exposure to polycyclic aromatic
hydrocarbons (PAHs) - a by-product of combustion present in high
levels in heavy-traffic areas - during their pregnancy with backpack
The researchers found a significant association between chemical
changes which control activation of the gene and high levels of
maternal PAH exposure.
Although the finding needs to be confirmed in larger studies,
researchers say changes in the ACSL3 gene may be help early diagnosis
of pollution-related asthma.
It is an example of an epigenetic change - where environmental factors
influence the activity of genes but do not cause structural changes or
mutations in the genes.
Previous work suggests the ACSL3 gene is involved in the structure of
But more work is needed to unpick the role of the gene in asthma.
Studies have suggested asthma risk is linked to environmental
pollution in early life and the incidence of asthma is higher in areas
with high traffic density.
"Our data support the concept that environmental exposures can
interact with genes during key developmental periods to trigger
disease onset later in life, and that tissues are being reprogrammed
to become abnormal later," said Dr Shuk-mei Ho, study leader and
director of the Center for Environmental Genetics at the University of
She said detecting early signs of asthma could help prevent the
disease than can affect as many as 25% of children in areas with high
levels of traffic pollution.
Dr Keith Prowse, vice-president of the British Lung Foundation, said
the study was interesting.
"We know that children living in polluted areas have a higher
incidence of asthma but what we didn't know was it was affecting a gene."
"If you look at cord blood and you find the gene has been modified you
know the child is more likely to get asthma so you can treat them early."
He added there were probably many factors contributing to the
development of asthma so the issue was fairly confused but in 10
years' time there would be a clearer picture.
Dr Elaine Vickers, research relations manager at Asthma UK, said: 'We
don't yet know whether air pollution can actually cause asthma and
although this study is very interesting, further research is needed
before we can say for sure.
"We do know however that pollution triggers symptoms in two thirds of
people with asthma, and many say that a reduction in air pollution
would make the single biggest difference to their quality of life."