MONTREAL - Anti-tobacco advocates are using a new Quebec study to make the case for a smoking ban on outdoor patios.

A researcher at Johns Hopkins University in Baltimore, Maryland found harmful levels of second-hand smoke in a survey of Montreal bar patios.

Ryan Kennedy says the concentration of smoke was comparable to a smoggy day in Los Angeles or an area near a forest fire.

Kennedy says the tests show that second-hand smoke can be harmful even outdoors, on a windy day.

Quebec's anti-tobacco coalition says the tests show a ban is needed to protect bar patrons and staff.

Several provinces have already banned smoking on patios, including Newfoundland, Nova Scotia, and Alberta.

Yukon has also introduced a ban, along with a number of municipalities across the country.