inhaled and exhaled from our lungs
per minute – than adults: 400 ml/
min/kg compared with 150 ml/
min/kg.
As children are also prone to
mouth breathing due to enlarged
adenoids, they lose the benefit of
nasal filtering, with the result
that more air pollutants end
up in the lower airways. Add a child’s
increased activity rate, where they
take in more breaths per minute, and
the resultant exposure of the lungs to
air pollutants is even greater.
When children are exposed to air
pollution, the lungs and cardiovascular
system are the first to take a hit.
“Every lungful of air laden with
pollutants has the potential to cause
damage to the tissues, which manifests
itself by causing inflammation,”
explains Professor Hedley.
A child affected by exposure to air
pollution may have increased phlegm,
appear wheezy and begin coughing.
In more severe cases, it can trigger
asthma, result in infections and even
bring about a bronchitic reaction.
But in some children, the effects may
be silent, and not appear until many
years later.
Each pollutant affects the body
in different ways. “Polluted air is
actually a mixture of pollutants that
may have common or specific effects,”
explains Professor Ignatius Yu, head
of occupational and environmental
health at the Chinese University of
Hong Kong.
Ozone, for example, which is
soluble in the fluids that line the
respiratory tract, has the ability to
penetrate deeply into the area of
the lungs responsible for vital gas
exchange with the blood, resulting
in breathing problems and possibly
triggering asthma.
Carbon dioxide, when inhaled,
reacts rapidly with haemoglobin in
the blood, preventing the uptake and
transport of vital oxygen. Worse still,
it hangs around in the blood for hours
after exposure.
Nitrogen dioxide and sulphur
dioxide suppress the immune system
and place a child at an increased risk
of respiratory infections.
Some children, of course, are
more susceptible to the harmful effects
of air pollution than others. Those
with underlying chronic lung disease,
particularly asthma, are potentially at
greater risk than those who don’t have
such conditions.
Overall, Professor Yu cautions
that the long-term effect of air
pollution on children is suffocating.
“Inflammation reduces lung
function,growth and a child’s cardio-
pulmonary fitness. It reduces the
volume of oxygen the lungs can take in
and breathe.”
To play, or not to play?
It’s a terrible dilemma: we know
children should exercise, but exercise
speeds their breathing and increases
the throughput of air through their
airways.
“If children exercise in polluted
air, they’re dumping more of this
rather dangerous cocktail of particles
and gasses into their body system at a
higher level than if they were leading
a more sedentary lifestyle,” explains
Professor Hedley.
Even Professor Lai struggles
to find a solution of ensuring his
children, aged nine and five, get
enough exercise. “I am also worried…
Summer 2014
43
