A University of Washington study published in the New England Journal of Medicine reports that where you live in a city matters more to your health than which city you live in.
The authors found that different parts of a city have more exposure to fine particulate air pollution of less than 2.5 microns in diameter -- about 1/20th the size of a human hair or less -- than other parts of a city.
This type of air pollution has been found to cause heart disease and even death in women over the age of 50.
Living beside major roads, power plants or factories will increase the exposure and the risk of getting sick, the researchers found.
"When you live on a four-lane road, your levels are pretty high," said Brian McCarry, chair in environment and health at McMaster University.
"Right next to a major road, your exposure is quite different than if you live two blocks away. It's very dependent on where you live."
"This is much more immediate, real and happening everyday," said Dr. Stephan van Eeden, spokesperson for the Heart and Stroke Foundation."
"The effect this has on us directly is much more real than just the climate is changing and something is going to happen in 50 or 100 years. This is with us. This affects everybody," he said.
The researchers 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. They assessed the women's exposure to air pollutants using the monitor located nearest to each woman's residence.
Hazard ratios were estimated for the first cardiovascular event, adjusting for age, race or ethnic group, smoking status, educational level, household income, body-mass index, and presence or absence of diabetes, hypertension, or hypercholesterolemia.
The study found that a total of 1,816 women had one or more fatal or nonfatal cardiovascular events, as confirmed by a review of medical records, including death from coronary heart disease or cerebrovascular disease, coronary revascularization, myocardial infarction, and stroke.
In 2000, levels of exposure to particulate matter of less than 2.5 m in aerodynamic diameter (PM2.5) varied from 3.4 to 28.3 g per cubic meter. Each increase of 10 g per cubic meter was associated with a 24% increase in the risk of a cardiovascular event and a 76% increase in the risk of death from cardiovascular disease.
For cardiovascular events, the between-city effect appeared to be smaller than the within-city effect. The risk of cerebrovascular events was also associated with increased levels of PM2.5.
