Pollutants from China have been
showing up in the air above West Marin, according
to recent scientific findings.
A statewide study has found Chinese pollution
in the skies above California. But media reports
have falsely associated the study's findings with
a decrease in local air quality. While the
research shows that Chinese air pollution is
possibly influencing global climate change it is
not impacting the air we breathe, said scientists.
Research on Mt. Tam
Since May, a research team from the University
of California at Davis has collected air born
particles atop Mount Tamalpais to see if Chinese
pollution can be found there. The Tamalpais site
has been in operation since May and is one of
three across the state.
Along with the Mt. Tamalpais site, two other
particle collectors are at Mount Lassen and Donner
Summit near Lake Tahoe and have been collecting
Particles in the free troposphere
All three sites were chosen for their
altitudes, which put them above what is called the
boundary layer. This part of the atmosphere, from
the ground up to roughly 2000 feet, is the lowest
level of the atmosphere and is where most local
pollution and air particles exist. The mountains
on which the collectors sit stick above the
boundary layer into what is called the free
troposphere. These two layers of atmosphere don't
often mix. Most of the particles that pass above
the California sky in the free troposphere stay
there. So they are basically unadulterated in
their long passage over the Pacific Ocean.
By collecting particles from the air mass that
comes directly from over the largest ocean on the
planet, Steve Cliff the atmospheric scientists who
heads the particulate study on Mt Tamalpais hopes
to gain an understanding of how particles in the
air impact climate change. With accurate
measurements of this air mass's particles he can
get a sense of the particulate matter around the
Chinese air pollution
not affecting local
While there have been a series of articles in
the national press about the negative impact of
Chinese particle pollution on local air quality,
Cliff, said that his research was misconstrued.
"We don't believe Chinese particulate air
pollution is a large air quality issue at this
time in the United States," said Cliff.
While pollution from Chinese industrial growth
is not affecting the air that we breathe it is
increasingly polluting the upper atmosphere with
particulates from coal-burning power plants
according to findings by the UC Davis group. The
Chinese are set to build one new coal power plant
every week in order to keep up with the
electricity needs of their rapidly urbanizing
While Cliff said he is unsure about the impact
of these particles on climate change until he has
more data, other scientists are more certain. Some
studies have even shown that in the short term
particles reflect the sun's rays and help cool the
earth. But other scientists counter that in the
long run they will have a warming effect.
"Particles in the atmosphere from China are
increasing global warming," said Thomas Cahill
another atmospheric scientists out of UC Davis.
Local air pollution worse
In most cases local pollution is much more of a
factor in air quality than anything coming from
The same is true along the coast of Marin; most
particulate air pollution is created locally.
While the marine layer along the coast does a good
job at cleaning the air of West Marin there are
still local sources of pollution, said Cort
Anastasio an assistant Professors at UC Davis'
Department of Land, Air and Water Resources.
According to a particulate testing station in
the Point Reyes National Sea Shore, 30 percent of
small particulates in the boundary layer along the
coast are from ammonium sulfate and another 10
percent comes from ammonium nitrate.
While it's difficult to gauge exactly where
these particles come from, Bret Schichtel a
physical scientists with the Park Service which
oversees 170 air testing sights nation wide, said
the pollution most probably comes from off-shore
shipping and inland pollution. The prevailing
winds carry pollution from tanker ships' diesel
engines onto the coast and periodic offshore winds
blow inland pollution out though the Golden Gate
along the coast. Yet all and all the majority of
particulate matter in the air of West Marin is sea
"The whole Northern Californian coast is quite
clean," said Anastasio, about the region's air
The results of the study on Mt. Tamalpais are
only preliminary, said Cliff. And he plans to
measure year-round particles in conjunction with
the two other sites he monitors. The study on Mt.
Tamalpais is located on Marin Municipal Water
Distinct land and is funded by the National
Oceanographic and Atmospheric Administration and
the California Energy Commission.