Graphic health warnings on cigarette packs work but only if they cover almost the entire package, according to a new report from researchers at Health Canada.

The Canwest News Service reported Sept. 3 that the study found that the warnings would have to cover at least 90 percent of cigarette packages to achieve significant deterrent effects. Currently, graphic warnings on cigarettes sold in Canada cover half the package; researchers determined that increasing that to 75 percent would have only a small and short-lived impact on smokers.

The study, conducted by the Montreal polling firm Createc, questioned smokers on the impact of warning labels covering 75, 90, and 100 percent of cigarette packs.

Other recent research found that the percentage of Canadian smokers deterred by the current graphic warnings has declined by 5 points in five years.

Researchers also recommended that warnings cover the entire cigarette pack in order to deter teen smokers.

"Findings suggest that increasing the current size of warnings of cigarette packages is not very effective to negatively affect image of smokers or perception of cigarette product attributes, unless health warning messages occupy the entire front panel," the study said.