You probably don't need another reason to dislike smog, but here goes anyway: It can raise your blood pressure. "We discovered a significant risk of developing high blood pressure due to exposure to air pollution," such as coal burning, vehicle exhaust, and dirt and dust in the air, says Tao Liu, lead author of a study published in the journal Hypertension. Per a press release, Chinese researchers looked at 17 studies from Brazil, Canada, China, Denmark, Germany, Iran, Sweden, Taiwan, and the US that involved a total of about 328,000 people, HealthDay reports. They found that people exposed to carbon monoxide, nitrogen oxide, ozone, sulfur dioxide, and other pollutants were more likely to have readings of above 140mm for systolic blood pressure (the top number), according to Time. Normal is less than 120, per the American Heart Association.
Previously, the link between pollution and high blood pressure was "controversial," per HealthDay, which notes that hypertension raises the risk of heart attack and stroke and is associated with about 17% of deaths worldwide. So what can you do? "People should limit their exposure on days with higher air pollution levels," Liu says, "especially for those with high blood pressure. Even very short-term exposure can aggravate their conditions." The findings are not the final word on smog and high blood pressure, per Time, and the researchers want to take a closer look at the link between particulate matter and hypertension. HealthDay says the study did not "establish a cause-and-effect relationship." But a doctor interviewed by Time says the results should get lawmakers talking about how to improve air quality. For the time being, she says, doctors should advise people to "lower the salt in their meals, cook in a healthier way, and exercise." (Pollution may be making the planet greener.)