SAN FRANCISCO -- A new San Francisco ordinance went into effect Thursday, forcing smokers to pay 20 cents extra per pack to cover the costs of cleaning up discarded cigarette butts throughout the city.

The controversial law, the first of its kind in the nation, was among Mayor Gavin Newsom’s budget proposal for the upcoming year. It was approved by the Board of Supervisors in July.

The fee will be collected from retailers and will go specifically to city departments that conduct street cleanup of cigarette butts.

The mayor's office said that discarded cigarette butts account for a significant portion of the litter that has to be cleaned from sidewalks and gutters, and can leach toxins into the environment.

According to the Department of the Environment, the city expects to make about $6 million each year from the cigarette fee, the bulk of which will go to the Public Works and Recreation and Park departments.

The local tax added to the 87-cent state tax and $1.01 federal tax pushed the price of a pack of cigarettes for San Francisco to about $7 a pack.