Vancouver Mayor Gregor Robertson says the annual 4/20 marijuana-smoking rally is "very disruptive" and better planning by police and city officials required to manage it.

"Certainly the city and VPD are always looking to improve the management of these big demonstrations and protests," he said Tuesday when asked about this week's event during a news conference on transit.

"I know there will be lessons learned from what happened yesterday. There were certainly more challenges this year than ever before."

Story continues below advertisement

His comments Tuesday came a day after 25,000 people gathered on the grounds of the Vancouver Art Gallery, blocking traffic as marijuana was smoked and consumed in food items.

Providence Health Care reported that 64 people had to go the St. Paul's Hospital ER for treatment of nausea and vomiting due to eating marijuana-laced food products such as cakes and smoothies as well as diminished consciousness and minor injuries.

While 4/20, which is held across North America every April 20, previously featured the need for some medical response, the numbers were up in Vancouver this year, said Providence spokesperson David Lefebvre.

The mayor said city and police made plans to manage the protest but may have been caught short.

"In this case, the scale of it, the number of people attending was huge and had much more impact than in past years," said Mr. Robertson.

Mr. Robertson said 4/20 is difficult to manage when "it busts well beyond the size that was anticipated."

The mayor said the outcome of this fall's federal election may help resolve aspects of the debate over access to marijuana in Canada, apparently referring to Liberal Party of Canada musings about legalization and the NDP talking about decriminalization.

Story continues below advertisement

"Perhaps there will be a change next year if the federal election has an outcome that changes the course of history with marijuana legislation."

Mr. Robertson says the growth of the protest shows how "intense" the issue around marijuana legalization is.

"With a federal election this year, there's a lot of attention on the marijuana issue and that showed on the streets of Vancouver, which was very disruptive."

On a related issue, Mr. Robertson said to stay tuned for city action next week on marijuana dispensaries and the regulation of such operations.

"The city has a challenging role with the dispensaries and we're looking at next steps with that. Expect to see some next steps next week in council."