Geoscience Reference
In-Depth Information
The amounts and sources of atmospheric CO change with locale and season. In
Africa, for example, the seasonal shifts in CO are tied to the widespread agricultural
burning that shifts north and south of the Equator with the seasons.
The related HELIX-Israel project is still in its organizational and fund-raising stag-
es. Niskar, now a faculty member at the Tel Aviv University School of Public Health
and director of HELIX-Israel, says the portion of the project that would use satellite
data on air pollutants may begin as early as 2009. She says the Israeli project could be
even more revealing than its Atlanta counterpart because the public health data avail-
able in Israel are of higher quality than those in the US, and the network of ground
monitors is denser, allowing for better cross-checking of satellite and ground data. If
the project is successful, Niskar says she is eager to help other countries set up similar
systems. She would also like to include other health outcomes beyond the initial respi-
ratory and cardiovascular targets and other pollutants (such as ozone) once NASA and
others develop accurate methods for determining ground-level concentrations.
Another project will look at links between PM
2.5
and health outcomes such as
stroke, blood pressure changes, cholesterol levels, deep vein thrombosis, and cogni-
tive function. The REGARDS project (Reasons for Geographic and Racial Differenc-
es in Stroke), a multicenter study sponsored by the National Institute of Neurological
Disorders and Stroke, already has 30,228 volunteers signed up in the lower 48 states
and may be able to begin the satellite-related portion of its work as soon as 2009 if
NASA funding comes through, says Leslie McClure, an assistant professor of biosta-
tistics at The University of Alabama at Birmingham. “This is all very cutting-edge,”
she says. “To be able to estimate exposure for someone in the plains of Kansas where
monitors are scarce is an extraordinary power.”
CLOSING IN ON GASES
Satellite tracking of several gaseous pollutants also is improving. One class of such
pollutants is the nitrogen oxides (NO
x
), which are created primarily through vehicle,
power plant, and industrial combustion processes, as well as by natural sources such
as fires, soils, and lightning. The NO
x
, despite their short lifespan in the lower atmo-
sphere, play a key role in the formation of ground-level ozone, acid rain, and green-
house gases. The NO
2
, along with other toxic by-products of NO
x
reactions, can cause
health problems such as premature death, cancer, and respiratory and cardiovascular
effects. The NO
2
is typically used by researchers and regulatory agencies as a surro-
gate for NO
x
reaction by-products.
The NO
2
is one of the easier pollutants to track via satellite because of its spectral
signature. “You can see it all the way down to the surface,” says Mark Schoeberl,
project scientist for NASA's Aura satellite, which carries several pollutant monitoring
instruments. This has made it relatively simple to capture extensive satellite data about
the global movement of this compound. There are a number of hotspots for the origin
of NO
2
, and the pollutant can travel long distances. Portions of eastern China are major
generators all year long, and moderately high emissions come from areas in Europe,
the eastern US, and central and southern Africa during much of the year.
