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Combining the assets of NASA and the EPA with NOAA’s weather
information is at the heart of a new NASA Earth Science Applications project called IDEA: Infusing
Satellite Data into Environmental Air Quality Applications. The goal of IDEA is to improve the EPA’s
decision-making tools with NASA satellite observations for better air quality forecasts. The project was
conceived and planned by Szykman, along with Jack Fishman and Doreen Neil, researchers at NASA’s Langley
Research Center. Szykman stumbled into research on air quality from a graduate school background in
water resources. While his wife was getting a Ph.D. in business at the University of North Carolina,
Szykman’s scientific expertise was broad enough to get him a position at the EPA’s office in Research
Triangle Park, just outside Raleigh. The office devotes most of its activities to air quality research
and national programs. |
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“In part, my wife Lisa also prompted my work with NASA,” says
Szykman. When she accepted a faculty position at the College of William and Mary, the move brought them
within 20 miles of NASA’s Langley Research Center in Virginia. “Jack had a long history of working with
the EPA office in Research Triangle Park,” says Szykman, “and the timing seemed to be right to increase
the collaboration between NASA and EPA offices there. While there are many others involved with this
work, Jack, Doreen, and I had an ‘IDEA’.”
First, the team wanted to demonstrate how NASA’s satellite observations could improve computer models—the
decision-making tools—used by EPA forecasters to predict pollution caused by aerosols. In the future,
they will expand their work into improving computer predictions of other major air pollutants, like
ozone or carbon monoxide.
What’s in the Air We Share
According to Szykman, the collaboration is just a step ahead of a shift in the nation’s
data needs for air quality management. Agencies are beginning to realize that air pollution must be
tackled on a regional basis: Denver’s “brown cloud” winds up in Rocky Mountain National Park, while the
Great Smoky Mountains are hidden beneath the haze of pollution from cities and power plants as far away
as Chicago, Detroit, Indianapolis, and St. Louis. In 1997, when the EPA began to enforce stricter rules
for controlling ground-level ozone pollution (the cornerstone of smog), 11 states in the Northeast
appealed to the EPA for waivers on the grounds that their failure to curb ozone pollution to acceptable
levels was because of pollution wafting in from other states. |
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The EPA routinely measures ground-level ozone (left)
and particle pollution with a diameter of 2.5 micrometers or less (right), the two most significant
contributors to regional haze. Measurement locations (colored circles) for air pollutants are widely
scattered, and only provide information about current conditions in a localized area (gray areas on maps
represent places with no data). To solve regional air quality problems, EPA scientists need to know
where pollution comes from and where it ends up. (Maps courtesy EPA AirNow) |
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While the regions the EPA needs to monitor grow larger, the size of the
particles they need to track is growing smaller. In 1997, under the Clean Air Act, the EPA issued a new
set of National Ambient Air Quality Standards for fine particulate matter, or PM2.5, which are particles
with a diameter less than 2.5 microns. These particles are so tiny—a micron is only one millionth of a
meter—that an individual particle can only be seen with a microscope. Spewed by the trillions out of
power plants, automobile exhaust pipes, fireplaces, and forest fires, these particles mix with each
other and with larger particles to create a hazy blanket that often spreads far from the original
source. The EPA calls pollution caused by aerosols “particle pollution.” |
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Air pollution often spreads far from its source. These
photographs of Rocky Mountain National Park in Colorado show the difference between a clear day (left)
and an extremely hazy one (right). The haze often blows into the park from nearby Denver. (Photographs
courtesy Interagency Monitoring of Protected Visual
Environments) |
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The PM2.5 particles’ tiny size makes them particularly treacherous to public health because
the smaller the size, the easier it is for the particles to slip through the lung’s defenses, causing or
worsening breathing problems in many people. According to an EPA report called “Latest Findings on
National Air Quality: 2002 Status and Trends,” about 59 million people in the United States—that’s just
over 20 percent of us—live in counties where the PM2.5 concentrations regularly exceed the safe limit
set by the EPA.
In December 2002, the EPA administrator signed a proposed suite of actions to reduce current levels of
power plant emissions. One of the actions is the Interstate Air Quality Rule, which targets sulfur
dioxide and nitric oxide emissions in 29 Eastern states and Washington, D.C. Those two types of
emissions contribute significantly to the fine particle and ozone pollution that creates regional haze,
such as the Midwest event Szykman described.
The Future of Particle Pollution Forecasting
The need to monitor tiny particles over a wide region is a major change from previous air
quality standards, according to Szykman. The EPA’s existing ground-based monitoring networks within
North America are located primarily in urban areas. They provide detailed measurements on the kinds and
amounts of pollution in the air. “These networks already cost the agency’s Office of Air Quality
Planning and Standards about $200 million a year to operate,” says Szykman. “Adapting these existing
networks for tracking regional haze would require substantial additions or reconfigurations of existing
networks.”
When scientists make air quality forecasts these days, they focus on atmospheric processes in the lower
atmosphere (near Earth’s surface), urban-scale models of pollution transport, and ground-based
measurement networks. This approach works for predicting whether the pollution present in a city today
will lift out by tomorrow, or whether joggers should consider taking their daily run on an indoor
treadmill, but it wouldn’t have predicted, for example, that smoke from devastating forest fires in
southern California in late October 2003 would wind up on the doorsteps of Maine in early November.
That is where NASA comes in. Not only do NASA scientists have experience in creating and running
regional-and global-scale models of how the atmosphere moves aerosols around, but they also have
satellites that observe aerosols on regional and even global scales. While EPA’s measurements are more
detailed but localized, NASA’s satellite measurements are less specific but comprehensive. According to
Szykman, fusing these complementary approaches is the future of particle pollution forecasting. Using
this technique for other major pollutants, like ozone or carbon monoxide, could revolutionize how
forecasters determine the overall air quality for a region.
Data
Fusion A New
IDEA in Air Quality Monitoring |
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This image shows a magnified view of aerosol particles
collected in the industrial city of Port Talbot, England. Many of the particles measure roughly 2.5
microns across, small enough to easily enter and damage human lungs. (Micrograph adapted from Sixth
Annual UK Review Meeting on Outdoor and Indoor Air Pollution Research 15th–16th April 2002 (Web Report
W12), Leicester, UK, MRC Institute for Environment and Health)
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