Landmark study links air pollution to accelerated buildup of calcium in arteries

Scientists have known for years that long-term exposure to air pollution raises the risk of heart disease, but a highly anticipated study finally explains why.

In a decade-long analysis involving more than 6,000 people in six US states, University of Washington environmental health expert Dr Joel Kaufman found that people living in areas with more outdoor pollution built up calcium in the arteries of their hearts faster than those who lived elsewhere — increasing a known risk for heart attack and stroke.

“On average we found a 20 per cent acceleration in the rate of the calcium deposits,” said Kaufman, 54, director of the UW’s occupational and environmental medicine program. “I would say the results are a little more clear-cut and dramatic than I expected when I started this.”

The US$30 million study, funded by the US Environmental Protection Agency and the National Institutes of Health, is the largest to measure both metrics of air pollution exposure and health markers over time. Results were published Tuesday in the journal The Lancet.

It relied on data collected through the Multi-Ethnic Study of Atherosclerosis and Air Pollution (MESA Air), which studies the effects of pollution in six US metropolitan areas: Baltimore, Chicago, Los Angeles, New York, and St Paul, Minnesota, and Winston-Salem, North Carolina.

Through what authors of an accompanying Lancet editorial called “meticulous measurements,” Kaufman’s analysis looked at the exposure of participants to the fine particulate matter present in pollution, tiny bits less than 2.5 microns in diameter, too small to be seen with the naked eye. Those fine particles are referred to as PM 2.5.