-- Mary Elizabeth Dallas
SUNDAY, Feb. 17 (HealthDay News) -- Levels of ozone and of air
pollution are directly linked to heart attacks, according to a new
study from Houston.
For both ozone and airborne fine particulate matter (tiny solid
and liquid pollutants such as those emitted by cars and factories),
peak exposure was found to increase the risk for heart attack
nearly 5 percent. Men, blacks and people older than 65 were at
greatest risk, the investigators found.
These findings should prompt health officials to continue their
efforts to reduce air pollution and provide the public with early
warnings of high ozone levels, the study authors suggested.
"The bottom-line goal is to save lives," researcher Katherine Ensor, a professor and chair of the department of statistics at Rice University, said in a university news release. "We'd like to contribute to a refined warning system for at-risk individuals. Blanket warnings about air quality may not be good enough. At the same time, we want to enhance our understanding of the health cost of pollution -- and celebrate its continuing reduction."
In conducting the study, Ensor and colleagues examined eight
years of data on air quality in Houston. They also reviewed
information compiled by Houston Emergency Medical Services on more
than 11,000 heart attacks that occurred outside of the city's
hospitals. More than 90 percent of cases were fatal, and 55 percent
occurred during the heat of summer.
Heart attacks were linked to exposure to both ozone and
particulate matter smaller than 2.5 micrograms in the air. An
average increase in fine particulate matter of 6 micrograms per day
over the course of two days increased the risk for heart attack by
4.6 percent. People with pre-existing health problems would be at
particular risk, the researchers noted.
Similarly, an ozone level increase of 20 parts per billion (ppb)
in one to three hours increased the risk for heart attack up to 4.4
percent. However, nitrogen dioxide, sulfur dioxide and carbon
monoxide levels did not affect the number of heart attacks, the
Study co-author David Persse, EMS physician director for the
Houston Fire Department, said that EMS workers have long believed
that certain types of air pollution, including ozone, have serious
harmful effects on people's hearts and lungs. "But this
mathematically and scientifically validates what we know," he said
in the news release.
The American Lung Association ranked Houston eighth in the
United States for high-ozone days. The city is taking steps to
reduce fatalities from heart attacks, such as increasing education
on bystander CPR (cardiopulmonary resuscitation) in at-risk
The best way to prevent the harmful effects of exposure to air
pollution, however, is to improve air quality, according to
Houston's Health and Human Services Department.
Rice University environmental engineer Daniel Cohan said that
environmental strategies that reduce ozone year-round may be
The researchers noted their findings could have important
implications as states plan to meet national ozone standards.
Although standards are now set at 75 ppb, the U.S. Environmental
Protection Agency is considering tightening them to between 60 ppb
and 70 ppb.
A 2012 study from Rice determined that the EPA's particulate
standard of 35 micrograms per cubic meter does not go far enough to
protect people's health.
The findings were scheduled for Sunday presentation at a meeting
of the American Association for the Advancement of Science, in
Boston. The study will also be published in the journal
Visit the U.S. National Institute of Environmental Health
Sciences to learn more about
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