Air Pollution and Cardiovascular Disease

There a very important piece of research published in this week's issue of the prestigious New England Journal of Medicine, indicating that air pollution increases the risk of cardiovascular disease, at least in women.  The whole article is available for free download.

Researchers from the University of Washington studied 65,893 postmenopausal women without previous cardiovascular disease in 36 U.S. metropolitan areas from 1994 to 1998, with a median follow-up of 6 years. All the participants were aged 50 to 79 and part of the Women's Health Initiative, a major US Government funded investigation into the causes of heart disease in women. A total of 1,816 women suffered one or more cardiovascular event.

The investigators were particularly interested in tiny airborne particles called particulates, which are less than 2.5 microns across, and can lodge in the lungs. Previous research had incriminated them in heart disease. These are the dense clouds that you see coming out of chimneys or exhaust pipes. They found that pollution levels varied between four to nearly 20 micrograms per cubic meter.

Each 10 microgram rise was matched by a 76% rise in the chances of dying from heart disease or stroke. For women living within, rather than between, cities, the risk more than doubled, increasing by 128%, with each step up in pollution levels.

It is not clear whether women are more susceptible to pollution than men. Women's coronary arteries are smaller and this might render them more vulnerable.

These results suggest that the risk from air pollution is far greater than most doctors previously thought, though it is still not clear how these sooty particles lead to the development of heart disease.

I live just outside a city where we often have smog advisories for weeks at a time in the summer. This research adds to the growing evidence that air pollution should be taken seriously as a risk factor for cardiovascular disease.

That also means that when localized air pollution is particularly high, people with chronic lung disease or coronary heart disease should avoid staying outside.

This problem will likely get worse as the summers be progressively warmer.

Yet another reason for taking climate change seriously.

“For the first time in the history of the world, every human being is now subjected to contact with dangerous chemicals, from the moment of conception until death.”
--Rachel Carson (American Biologist and Writer, 1907-1964)