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POLLUTION from coastal cities and ships mingles with
chlorine compounds in sea air, triggering reactions that
boost smog formation, US scientists found.
The
team, led by researchers at the US National Oceanic and
Atmospheric Administration and the
University of
Colorado
in Boulder, studied the air quality near Houston and
Galveston in Texas in 2006.
Emissions of two forms of nitrogen oxide collectively
known as NOx led to quantities of another compound,
nitryl chloride, more than 20 times higher than in
“clean” areas, the scientists said in Nature Geoscience.
That compound, in turn, triggered reactions leading to
the formation of molecules including ozone that can harm
both human health and the environment.
“The NOx
pollution from cities and ships is combining with
chloride on particles to make a form of chlorine that
accelerates smog formation,” said Jim Roberts, a
University of Colorado scientist and one of the paper’s
authors.
While
ozone high in the atmosphere protects people from the
sun’s harmful ultraviolet rays, at ground level, it’s
“the smog ozone that irritates our eyes and lungs,
compromises people’s health and damages crops and other
ecosystems,’” Roberts said April 4 in an e-mail.
Roberts
and his colleagues found the series of reactions
triggered by the NOx pollutants led to the formation at
night of nitryl chloride. When exposed in the morning to
sunlight, the compound helped speed up the development
of ozone.
“Our
calculations indicate that as much as 10 percent to 30
percent more ozone is formed in the morning hours due to
this chemistry,’” Roberts said. “We are not sure how
widespread this effect is because ours are the first
measurements.”
The
chemistry resulting from pollution in marine areas
should be studied further because of the importance of
some of the substances to the environment, Roberts said.
Ozone in
the troposphere, or lower atmosphere, for example, acts
as a greenhouse gas, contributing to global warming by
trapping the sun’s energy, the scientist said. It also
helps drive chemical reactions that remove another
greenhouse gas, methane, from the atmosphere, he said.
(Bloomberg) |
