Studies Suggest Link Between Smog, Joint
SATURDAY, Nov. 5 (HealthDay News) -- Exposure to certain types
of air pollution is associated with an increased risk for the
painful joint disease known as rheumatoid arthritis, new research
This link is strongest for sulfur dioxide, one of the six most
common air pollutants in the United States, according to the
findings from two studies scheduled to be presented Wednesday at
the American College of Rheumatology annual meeting, in
In the studies, investigators looked at 2,092 rheumatoid
arthritis patients and more than 93,000 people without the disease
in the United States and Sweden, and used their home addresses to
estimate their long-term exposure to several common air pollutants,
both gaseous (for example, carbon monoxide, sulfur dioxide and
nitrogen dioxide) and particulate (soot or dust).
There was no evidence of increased risk of rheumatoid arthritis
associated with particulate air pollution. But increasing exposure
to sulfur dioxide and oxides of nitrogen in the 10 and 20 years
prior to onset of rheumatoid arthritis was associated with
increased risk of the disease among the Swedish participants, the
Low-, medium- and high-exposure to sulfur dioxide, nitrogen
dioxide or nitrogen oxide were associated with an up to 7 percent,
11 percent and 7 percent increased risk for rheumatoid arthritis,
respectively, according to the Swedish study.
These increased risks of rheumatoid arthritis were higher in
people with less than a university education than in those with at
least a university education. Education levels are a measure of
People "with a lower socioeconomic status are more likely to
live in houses where more air pollution leaks in from the outside
or other factors such as general health status that may make them
more susceptible to the effects of air pollution," Dr. Jaime Hart,
an instructor in medicine at Brigham and Women's Hospital in
Boston, said in an American College of Rheumatology news
Hart was lead investigator of the U.S. study and was scheduled
to present the U.S. and Swedish findings at the meeting.
The U.S. study found that only exposure to sulfur dioxide was
associated with modest increases in rheumatoid arthritis risk.
Those with a high exposure to sulfur dioxide had a 5 percent
greater risk of rheumatoid arthritis than those with low
But Hart noted that the U.S. participants were part of the
Nurses' Health Study, which meant they may have had a higher
overall socioeconomic status than the Swedish participants.
Study data and conclusions presented at medical meetings should
be viewed as preliminary until published in a peer-reviewed
About 1.3 million Americans have rheumatoid arthritis, which
typically affects women twice as often as men. Previous research
has suggested a connection between environmental factors and
The American Academy of Family Physicians has more about
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