Pittsburgh, a former steel-making center once known
for its sooty skies, is the worst US city for short-term
particle pollution, the American Lung Association announced
in a recent report.
It was the first time a city outside California topped
any of the association's three lists for different kinds
of pollution in its annual 'State of the Air'
Greater Los Angeles was listed as the worst city for ground-level
ozone - also known as smog - and year-round particle pollution.
Pittsburgh had the second-worst year-round particle pollution,
the association said.
The shift occurred because Los Angeles took action to clean
up particle pollution - tiny particles that can be inhaled
and lodge in the lungs - the association's Janice Nolen said.
In Pittsburgh, the biggest source of particle pollution is
a steel plant in nearby Clareton, Nolen said. There are plans
to reduce that kind of pollution in Pittsburgh - but, because
the report uses data from 2004 to 2006, those changes are
not evident in the current report, she added.
Overall, the report found that 42 percent of US residents
- or nearly 125 million people - lived in counties with unhealthy
levels of either ozone or particle pollution. "We had seen
some real improvement in a lot of areas in the first part
of this century, but now we're seeing a levelling-off" - Nolen
The earlier improvement was due, partly, to measures
to clean air pollution from power plants in the eastern
US, she said.
However, other factors are pushing up pollution levels,
including more electricity generation and an increase
in the distances travelled by polluting vehicles.
"That can add pollution and can make it harder to clean
up the pollution already there."
Ozone - a gas that forms when sunlight reacts with emissions
from motor vehicles, factories and power plants - irritates
the respiratory tract and can cause asthma attacks, coughing,
wheezing, chest pains and premature death, the report said.
Short-term particle pollution, which affects over 81 million
US residents, involves sharp, brief rises in the level of
sooty particles in the air, lasting from hours to several
days. Those episodes can increase the risk of heart attacks,
strokes and emergency-room visits for asthma and cardiovascular
disease and can increase the risk of early death.
Long-term particle pollution involves lower levels of pollution
over longer periods of time, which can increase risk of hospitalisation
for asthma, damage lungs and increase the risk of premature
To download the report - 'State of the Air' - Click
For more information on the American Lung Association -