Fewer nonsmokers are inhaling second-hand smoke than in years past, thanks to recent laws that prohibit smoking in offices, bars, restaurants and other public places, a study from the U.S. Centers for Disease Control and Prevention concludes.
A decline in the number of adult smokers to slightly below 20 percent also is a factor, the Associated Press said, citing the study's conclusions.
Some 46 percent of nonsmokers had evidence of measurable blood nicotine levels between 1999 and 2004, compared with 84 percent of nonsmokers sampled in the late 1980s and early 1990s.
Exposure to second-hand smoke can increase a nonsmoker's lung cancer risk by at least 20 percent and the risk of heart disease by at least 25 percent, the wire service said.
Despite the decline, study co-author Cinzia Marano said the numbers were still too high. "There is no safe level of exposure," Marano told the AP.