Under the expanded labeling, people who smoke one pack per day would see antismoking messages at least 7,300 times and even more when accounting for each puff, said Geoffrey Fong, a psychology professor at the University of Waterloo, in Ontario, and principal investigator at the International Tobacco Control Policy Evaluation Project.

“There are no public health messages or messages of any kind that have that type of exposure,” said Professor Fong. “There’s a lot of potential for these dissuasive warning labels, dissuasive cigarettes, to be impactful.”

Estimates on the number of smokers in the country vary, but according to the data published last August by Canada’s census agency, there are 3.8 million daily and occasional smokers over the age of 12. About 48,000 Canadians die from smoking each year, the health agency said.

Dana G. Smith contributed reporting from Durham, N.C.