The U.S. Centers for Disease Control and Prevention (CDC) reports that 25 states had completely banned smoking from private-sector workplaces, restaurants, and/or bars by 2007, up from eight states in 2005.

Moreover, the number of states with no restrictions on smoking fell from 16 to eight during the same time period; the remaining 17 states had some restrictions on indoor smoking, such as requirements for a separate nonsmoking section, but did not prohibit lighting up indoors.

All of the changes reported in state smoking laws during the study period were moves toward increasing restrictions on smoking, the CDC found. By 2007, a dozen states banned smoking in all three settings where adults are most likely to be exposed to secondhand smoke, up from just three states in 2005.

"Smoking restrictions such as these reduce the risk of heart disease and lung cancer among nonsmoking adults," said Janet Collins, Ph.D., director of CDC's National Center for Chronic Disease Prevention and Health Promotion. "These findings are encouraging as they suggest that we may achieve the national health objective of establishing laws making indoor public places and worksites smoke-free in all states by the year 2010."

The study was reported in the May 23, 2008 issue of the CDC's Morbidity and Mortality Weekly Report.