Lung Disease & Respiratory Health Center

Air Pollution Increases Blood Pressure

April 2, 2001 -- Residents of many major cities have become accustomed to radio and TV alerts about unhealthy air quality, filled with warnings to avoid outdoor exercise during the worst hours. Now a team of German researchers has discovered yet another reason to stay inside on smoggy days.

"The authors found increases in blood pressure related to air pollution, especially to particulate air pollution," Henry Gong Jr., MD, professor of medicine and preventive medicine at the University of Southern California, Los Angeles, tells WebMD.

"We've learned that increasing concentrations of particulate air pollution affects several cardiovascular health [factors], such as blood pressure," author Angela Ibald-Mulli, MSc, MPH, tells WebMD.

"In previous papers, we discussed its effect on heart rate and [blood thickness]. This may explain the increase in cardiovascular mortality due to air pollution, which has been established in several mortality studies," says Ibald-Mulli, a junior scientist at the Institute of Epidemiology at the GSF-National Research Center for Environment and Health in Neuherberg, Germany

In this study, published in the April issue of the American Journal of Public Health, researchers examined nearly 2,700 men and women for the effects of air pollution. They found there was a consistent increase in blood pressure linked to the levels of particles in the air. Weather conditions, such as humidity and barometric pressure, also affected blood pressure levels.

"Numerous studies have found elevated air pollution, especially particulates, are statistically related to premature death, breathing problems, and admissions to hospital emergency rooms for heart and lung problems," Gong says. "Now we're trying to understand the mechanisms behind these statistics."

At this point, researchers can only speculate as to possible causes for the increased blood pressure, according to Ibald-Mulli. It may be related to dysfunction in the part of the nervous system that controls blood pressure, or due to a widespread inflammation in the body, which spreads from the lungs.

Gong warns that when air pollution levels are high, it is particularly important that people who already have heart or lung problems avoid vigorous outdoor exercise.

"Stay indoors, use air conditioning -- which filters out pollutants, and clean the filters," he says. "Take your medicines faithfully according to what your doctor prescribed. In terms of the larger picture, hopefully we can diminish and control air pollution problems through regulations and improved technology."

Not every expert is sold on the air pollution-blood pressure connection, however.

"Many things affect blood pressure," says William White, MD. "It's well known that blood pressure tends to be lower in summer than winter, because of the hot weather and because people tend to lose weight and be more active then. So it's difficult to sort out these complicated relationships, and I question whether there is a relationship between air pollution and blood pressure levels."

In any case, the most important ways to reduce blood pressure are to keep salt intake low, maintain a healthy weight, and be physically active, says White, who heads the hypertension division at the University of Connecticut Health Center in Farmington and is founder and editor of the journal Blood Pressure Monitoring.

"Those who have high blood pressure or heart failure should read food labels and make sure their daily intake of sodium is under 2 to 3 g a day," he says.