Nonsmokers's health could be threatened by secondhand smoking from their neighbors, demonstrating the need to have smoking-free buildings, the United States researchers say.

To determine the impact of neighbors'secondhand smoking on nonsmokers, researchers at Roswell Park Cancer Institute (RPCI) in Buffalo, New York, analyzed air quality data from 30 apartments within 11 buildings.

The findings show that secondhand smoke can travel from the apartments of smokers to hallways and apartments of nonsmokers. The extent of the secondhand smoking transfer depends on a number of factors, including ventilation and distance between apartments, according to the study published Thursday online in the journal Nicotine & Tobacco Research.

The researchers said the best way to protect apartment residents from secondhand smoking is to have smoking-free buildings.

"This study suggests that individuals who live in apartment buildings are particularly susceptible to secondhand smoking exposure in their homes," lead investigator Brian King, of RPCI's department of health behavior, said in a news release from the institute.

"Since many factors can impact the amount of secondhand smoking transfer between apartments, smoking-free building policies are the most effective way to protect apartment residents and their visitors from exposure."