For the fifth year in a row, the smoking rate among U.S. adults remains at about one in five, the Centers for Disease Control and Prevention announced Tuesday.

The new CDC study shows that secondhand smoke exposure is up as well, with 40 percent of all non-smokers still being exposed to the toxic smog.

Prior to 2004, the smoking rate had been falling dramatically since the 1960s.

"So why has the decline stalled? The answer really is quite simple," CDC Director Tom Frieden told ABC News. "The tobacco industry combined with the failure of governments and communities to do what we know to reduce tobacco use."

Frustrated health officials say that more anti-tobacco campaigns are needed to compete with the aggressive marketing of cigarette companies.

"While government efforts are often standing still or even moving backward, the tobacco industry is not standing still," Frieden said.