FAQ Sheet
What is Fine Particulate Matter?
The earth's atmosphere is composed primarily of gases, with nitrogen,
oxygen, carbon dioxide, and water vapor being most prevalent. However, the
atmosphere may also contain droplets of liquid and bits of solid matter (dust,
for example) that remain suspended for long periods of time. These
suspended particles vary in size and composition, but they can all be classified
as Particulate Matter.
Fine Particulate Matter refers to particles that measure less than 2.5 microns in diameter. In most cases, these particles are "secondary pollutants." They don't come directly from tailpipes, smokestacks and other emission sources. Instead, they are formed in chemical reactions that occur in the atmosphere.
Why should I be concerned about Particulate Matter?
Airborne particles find their way into living organisms through normal
breathing mechanisms. The particles may contain acids, heavy metals,
biological irritants, soot, and other substances. Fine particles may be
especially hazardous, as they are often too small to be screened out by the
body's natural filtering systems. Recent studies have found strong
associations between airborne particulate matter and adverse human health
effects, including premature death, aggravation of asthma and other respiratory
diseases, and decreased lung function.
What is a Supersite?
EXPLAIN ABOUT EPA AND HOW THERE ARE 6 SUPERSITES NATIONWIDE. FIRST
SUPERSITE STUDY WAS ATLANTA IN 1999.
Because particulate matter is so complex, it is not yet clear which of its chemical and physical properties are responsible for the observed health problems.
The Houston Supersite and approximately 5 similar supersites distributed around the United States will improve our understanding of Particulate Matter and its relationship to human health.
Why the Houston Area?
Houston in the fourth largest city in the United States, and it has recently
been cited as having the worst air quality of any US city, surpassing Los
Angeles in ozone concentrations. Background concentrations of Fine
Particulate Matter in the Southeast Texas area average 10 to 12 micrograms per
cubic meter (mg/m3). Industrial and
urban emissions within the area create "hot spots" where
concentrations are significantly higher. A recent report from the City of
Houston estimated that 2.5 million people may be exposed to annual average
concentrations above 15mg/m3.
Particulates in Southeast Texas come from a wide range of sources. The
Houston area contains the largest concentration of petrochemical manufacturing
plants in the United States, which offers excellent opportunities for tracking
particulates from industrial sources. The area also has typical urban
emission sources and a significant quantity of biogenic emissions. For
these reasons, the Houston area offers an ideal field laboratory for studying
the behavior of Particulate Matter. Researchers expect that data collected
in this study will be relevant to other cities on the Gulf Coast and those with
petrochemical activity.
What will researchers do?
Researchers will collect and analyze air samples at three core sites and 20
peripheral sites around Houston. The three core sites include:
Researchers will determine the chemical make-up of Fine Particulate Matter, its sources and formation, its extent variations between night and day, and variations throughout the year. They will also examine how particulate matter is transported, how it is affected by weather patterns, and how it affects lung tissue. The study will be coordinated with a 6-week intensive sampling program during August and September 2000, called the Texas Air Quality Study.
Project Timetable:
December 1, 1999 - June 2000: Selection and preparation of sampling
sites
June 2000 - September 2001: Air quality measurements in Southeast Texas
September 2001 - September 2003: Data analysis and modeling