ATLANTA — A new study from the Johns Hopkins Bloomberg School of Public Health ranks metro Atlanta as the second most sprawling metro area in the United States, behind Riverside, California.

Researchers say urban sprawl is having a major impact on affordability, transportation costs and health outcomes across the metro area.

Lead researcher Dr. Shima Hamidi says housing affordability is one reason many people choose to live farther outside the city.

“That’s probably the most discussed point when you talk about urban sprawl,” Hamidi said.

But the study found some households in metro Atlanta spend more on transportation than housing.

“We found households that spent 30-35% of their income on transportation,” Hamidi said.

Hamidi says transportation costs increase in sprawling areas because many households rely on multiple vehicles.

“Because most of the people in those households have to have multiple cars, and car ownership is expensive,” Hamidi said.

The study also found higher health and safety risks tied to sprawling communities.

“2.2 times higher risk of being in a fatal crash for a person who lives in a sprawling area, and 6.5 times higher risk of a pedestrian being in a fatal crash,” Hamidi said.

Researchers also found higher rates of hospitalizations for heart attacks, COPD and similar illnesses in sprawling areas.

Hamidi says there are benefits to living closer to urban centers, including more walking and outdoor activity.

“Driving less and walking more, and really all of those costs that are associated with the sprawl, you’ll feel that less when you have the community centers that are mixed used,” Hamidi said.

The study says metro Atlanta has made some improvements since a similar report in 2010, with areas including Midtown, Cherokee County and Forsyth County seeing population and employment gains.

“Atlanta is becoming more polycentric than what it used to be,” Hamidi said.

WSB Radio’s Jennifer Perry contributed to this story.