Northwest Researchers Study Link Between Air Pollution And Heart Disease

By Matt Ironside

Researchers specializing in air pollution agreed to expand their focus from lung associated health conditions like asthma and cancer to include heart disease.

In a January symposium at the University of Washington (UW), researchers studying particle air pollution concluded it is important to widen their research to examine links between pollution and heart health. The symposium was sponsored by the Environmental Protection Agency (EPA) Northwest Research Center for Particulate Air Pollution and Health, which is based at the UW and is one of five such centers in the U.S.

"There has been a whole reorientation of our thinking from particulate pollution being a lung problem to being a heart problem," says Phil Hopke, a professor of chemical engineering at Clarkson University in Potsdam, N.Y. and a member of the EPA Center's Science Advisory Committee, which met at the symposium.

An example illustrating the shift is a study, by graduate student Kristin Miller working with UW professor Joel Kaufman, examining development of cardiovascular disease in women with a chronic exposure to particle pollution.

The study, conducted using data from the Women's Health Initiative Observational Study, showed a 25 percent increase in cardiovascular events and a 70 percent increase in the incidence of death from cardiovascular causes in post-menopausal women. The increase was for each ten microgram per cubic meter difference in chronic exposure to particulate pollution. The study focused on small particles with a diameter in the area of 2.5 microns.

Increasingly, researchers are investigating as possible culprits not only 2.5-micron particle pollutants but also smaller ultra-fine particles, which may be as small as one-tenth of a micron. They say the small size increases the likelihood that the particles penetrate into the blood.

In an attempt to understand how pollution might be affecting cardiovascular health, researchers are using transgenic mice to see if particle exposure is somehow causing areas of arterial plaque to rupture, causing cardiovascular events.

The mice, genetically altered to rapidly build up arterial plaque, are being exposed to diesel exhaust to study the effects of particle pollution on the plaque.

Specialists say that diesel exhaust and wood stoves are some of the most common combustion sources of particle pollution in the Northwest.

Matt Ironside is a journalism student at the University of Washington.

Image

A cross section of a mouse carotid artery shows blood (red) in the plaque layer (aqua), the first stage of forming thrombi. Blood and other materials in the plaque can eventually cause thrombi to rupture. In humans, this leads to clotting around the rupture which contributes to a variety of conditions including stroke, angina, and heart attacks. Scientists are investigating whether particle pollution from diesel exhaust might accelerate blood build-up in the plaque. Photo: Jerry Ricks