|One month a year, it is not healthy to be outside in Houston.
Ozone. It can harm lung function and irritate the respiratory
system, convert cholesterol in the bloodstream into artery hardening
plaque, damage car tires, and stunt the growth of some plant species. It’s pale blue, and for as many as 35 days a year, high levels of ozone can be found for several hours in the air Houstonians breathe.
In the upper atmosphere, naturally occurring ozone protects the earth from the sun’s damaging ultraviolet light. In the lowest part of the atmosphere—the boundary layer—ozone is a destructive air pollutant, formed by a reaction
among hydrocarbons, nitrogen oxides, and sunlight.
“Houston has as many as 35 days of high ozone a year,
compared with the EPA’s recommendation of three days over a
three-year period,” says UH Assistant Professor of Atmospheric
Sciences Barry Lefer. “One month a year, for several hours a
day, it is not healthy to be outside in certain areas of Houston.”
In an effort to learn how ozone is being formed in
Houston and how to reduce it, a large multi-agency project
titled Texas Air Quality Study II (TexAQS II) has brought
hundreds of scientists to Houston for the months of August
Scientists from the National Oceanic and Atmospheric
Administration (NOAA), Environmental Protection Agency
(EPA), Texas Commission on Environmental Quality (TCEQ),
The University of Texas (UT), and numerous other agencies
and universities are working with experts from the UH
Institute for Multi-dimensional Air Quality Studies (IMAQS)
to examine Houston’s air quality.
Meteorological conditions, ozone, and many other
photochemical smog-related measurements are being taken
from the ground, by aircraft and ship, and with balloon-borne
Lefer and Associate Professor of Atmospheric Sciences Bernhard Rappenglueck, along with more than 40 visiting
scientists from different universities and national labs, are
working at the UH Moody Tower “Supersite,” an 18-stories-high rooftop lab, where measurement towers and sophisticated
instrumentation trailers have been set up.
In addition, measurements are being taken at the UH
Coastal Center in La Marque and other surface sites around
Houston, while weather balloons are launched two to six
times a day from the UH campus.
Among some of Rappenglueck’s studies are measurements
of organic nitrates to tell what kind of hydrocarbons are
making ozone and measurements of toxics in the air, which
are produced by gasses emitted from a variety of sources,
including industries and traffic.
Two of Lefer’s studies involve calculating the rate at
which sunlight is creating reactions that make ozone and
determining how clouds and particles in the atmosphere
reduce or produce ozone.
Using all of these measurements, IMAQS Director and
Professor of Atmospheric Sciences Daewon Byun will test
air quality models he has developed to predict where ozone
pollution is headed and which neighborhoods are getting the most impact. Byun is also providing daily weather and air
quality forecasting results from advanced computer models
for the EPA and the State of Texas to help determine if an air
quality alert should be issued.
“These measurements will be used to improve our
ozone forecasting and to help target culprit emissions that
exacerbate Houston air quality,” says Byun.
Visit the IMAQS Web site at www.imaqs.uh.edu/ozone_forecast.htm
for daily ozone forecasts.