FOLLOW YOUR NOSE: HOUSTON AIR QUALITY
STUDY FINDS A FEW SURPRISES
Mercury and Formaldehyde Levels Have Scientists Scratching Their
HOUSTON, August 20, 2007 – As a frequent addition to the
list of America’s most polluted cities, Houston is no stranger
to having more than just oxygen and carbon dioxide in the air. But
a University of Houston study found a few surprising results in
the air Houstonians breathe day in, day out: mercury and formaldehyde.
Although Houston’s air quality has improved from previous
years, the Texas Air Quality Study-II, a 45-day study conducted
in 2006, is the first to provide solid mercury measurements in Houston,
according to Barry Lefer and Bernhard Rappenglueck, UH professors
of atmospheric science.
“Formaldehyde has been measured before in Houston’s
air, but, to the best of my knowledge, mercury has not been measured
in Houston,” Rappenglueck said. “There is now a significant
amount of formaldehyde and mercury in the air here at times.”
Scientists know mercury is emitted mostly from coal-burning power
plants, such as the one in Sugar Land, but there is additional mercury
coming from the area around the Houston Ship Channel and the nearby
refineries and petrochemical plants, according to the study. The
more than 100 scientists from UH and research institutions across
the country who pored over the air quality data are still analyzing
the information to identify what industrial processes are producing
Most of the data was collected from the UH Moody Tower Atmospheric
Chemistry Facility, an 18-story building that is operational 24
hours a day, seven days a week, and from data collected from various
aircrafts and a National Oceanic Atmospheric Administration ship
in the Houston Ship Channel.
The Moody Tower facility measured three different types of mercury:
gaseous elemental mercury, reactive gaseous mercury and fine particulate
mercury. Although traces of mercury have been found all over the
country, the amounts detected varied from double to more than six
times what is typically found in other parts of the United States,
“Mercury is toxic and is most detrimental to children and
pregnant women and causes developmental abnormalities,” Lefer
said. “Mercury emissions from coal and other sources are going
to be more problematic to reduce, but using cleaner fuels and alternative
energy for electricity will reduce the mercury levels in the environment.”
The base for embalming fluid, formaldehyde is believed to be the
catalyst in the production of ozone, a harmful pollutant that may
be primarily emitted from traffic and poorly maintained diesel cars,
and secondarily by chemical reactions in the atmosphere.
“Primary formaldehyde means it is directly emitted to the
atmosphere,” Rappenglueck said. “Secondary formaldehyde
means that it is chemically formed in the atmosphere from other
Formaldehyde emissions from automobile exhaust are directly emitted
into the atmosphere, but their contribution is small, Rappenglueck
said. Instead, the air quality data suggests there may be a “new”
source of primary formaldehyde emissions in Houston.
“Once the source of the formaldehyde is identified, it should
be possible to figure out how to reduce these emissions,”
Lefer said. “Formaldehyde is not toxic at these levels, but
it is very efficient at producing ozone pollution. We think this
is one of the ‘missing’ links in understanding Houston’s
The UH Atmospheric Science group is working on calculations to
assess the impact of primary formaldehyde emissions in producing
ozone in Houston. They hope to have the results in time for conferences
in December and January.
The Texas Air Quality Study-II wasn’t all doom and gloom for
Houston, though. Houston does have a serious ozone problem, but
efforts to fix it are headed in the right direction.
“The bad news is that Houston’s ozone levels are above
the Environmental Protection Agency’s (EPA) standards for
30 to 40 days each year,” Lefer said. “The EPA allows
a city to have one to three ‘bad’ ozone days per year.
So we are well above this average. But, the good news is that the
number of ‘bad’ ozone days each year in Houston is decreasing.
In addition, the peak ozone values observed in Houston have also
been on a down trend the past six years. We still have a long way
to go, though.”
About the University of Houston
The University of Houston, Texas’ premier metropolitan research
and teaching institution, is home to more than 40 research centers
and institutes and sponsors more than 300 partnerships with corporate,
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in the country, stands at the forefront of education, research and
service with more than 35,000 students.
About the College of Natural Sciences and Mathematics
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centers, Texas Medical Center institutions and national laboratories.
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