High-cost cigarettes and smoke-free homes reduce smoking among people with low incomes, a new study concludes. Cigarettes that cost $4.50 or more per pack are associated with lower cigarette use, researchers from the University of California, San Diego found.

The results come from an analysis of U.S. Census Bureau data. The study found living in a smoke-free home reduces tobacco use and also helps prevent a relapse among people trying to quit, HealthDay reports. “Price is a deterrent to smoking, but successful quitting — 90 or more days — was associated in this study only with a smoke-free home,” lead researcher John Pierce said in a university news release.

“No one is mandating a smoke-free home,” he added. “We are telling people that if they really want to quit, then introducing a smoke-free home will help them be successful. This study supports the current policy of increasing (cigarette) prices and building social norms that protect against secondhand smoke. These policies will reduce consumption among all smokers – reducing potential harm – and the ensuing smoke-free homes will help smokers quit successfully.”

The findings are published in the American Journal of Public Health.