The odds that you’ll suffer cardiac arrest—or that someone will use cardiopulmonary resuscitation (CPR) to help you survive it—depends on what neighborhood you live in, according to a study in the June issue of the Annals of Internal Medicine.

Cardiac arrest is when the heart stops pumping blood through the body. That event is usually caused by heart attacks, but it may also be triggered by other health emergencies such as choking, drowning or electrocution.

For the study, researchers analyzed data from the Cardiac Arrest Registry to Enhance Survival Rates (CARES), a database that tracks 911 and Emergency Medical Services (CMS) calls about cardiac arrest and correlates them with the hospital medical outcomes.

Looking at the results for Fulton County, Georgia—which includes the city of Atlanta—researchers found that some neighborhoods had rates of cardiac arrest two or three times greater than the rest of the county. In addition, the data showed fewer passersby there were willing or able to give CPR. (No, this wasn’t a fluke—these risks were neighborhood characteristics for several years running.)

What set these neighborhoods apart from the rest? According to the study’s authors, the residents of these neighborhoods were poorer and less educated—and they were more often black.

“Nine out of 10 people die from a cardiac arrest event,” said Comilla Sasson, MD, MS, the study’s lead author. “This number can and must change.”

Sasson said she hoped to extend CPR training programs beyond the usual range of young volunteers so that more people in high-risk communities know how to use CPR to save a life.

Each year, close to 300,000 people die of cardiac arrest while not at a hospital. Broader access to CPR training could save as many as 1,500 lives in the United States annually.