ATLANTA: Almost half of nonsmoking Americans are still inhaling in cigarette fumes, but the proportion has decreased considerably since the early 1990s, according to an administration research released Thursday.

The major cause for the decline in cast-off smoke is the increasing number of laws and policies that proscribe smoking in workplaces, bars, restaurants and public places, stated by investigators associated with the Centers for Disease Control and Prevention.

Another reason is the decrease in the number of teenage smokers. It has currently inched below 20 Percent, according to 2007 CDC data.