Apparently environmentalists aren’t the only ones upset by the increase of smog in our atmosphere.

According to a study conducted by German researchers, there is a direct link between long-term exposure to air pollution and high blood pressure, even when other risk factors are considered. This means city dwellers are more at risk for heart disease than their rural brethren.

Of course there are all kinds of stresses linked to urban living, from crowds to noise to traffic. But this study of five-thousand people points at fine particulates in the atmosphere, finding that ups and downs in blood pressure correlated with higher or lower levels of particles in the air.

For their research, scientists used data from an ongoing study examining the development of heart disease. They looked at the effects of air pollution exposure on blood pressure over a three-year period. The researchers found that blood pressure rose after exposure to particles from cars, heating, industry and power plants. The increases tended to be greater in women than in men.

The researchers said the connection remained even when other factors, such as age, gender, smoking and weight were taken into consideration.

This is especially troubling because according to the American Lung Association, one-hundred-and-fifty-nine million Americans live in areas threatened by heavily polluted air. That’s a little more than half of the country.

Of course, worrying about this won’t help your blood pressure, either. And there is hope for the future: Although air pollution continues to be a problem, the U.S. Environmental Protection Agency says the country’s skies are cleaner now than they have been at any point since nineteen eighty. Now that’s a reason to look up.