Subscribe | UPI Odd Newsletter Subscribe VANCOUVER, British Columbia, April 15 (UPI) -- An indoor pool in Canada has decided to close on Wednesday, April 20 to avoid a massive event being planned by a group of marijuana enthusiasts. Staff at Vancouver Aquatic Centre feared that their ventilation systems would take in too much marijuana smoke from a "4/20" event expected to draw approximately 25,000 people. Advertisement "It's not possible to shut down intake fans," park board chair Sarah Kirby-Yung told the CBC. "Given the tens of thousands of people expected to be around the Aquatic Centre smoking marijuana that day, we are very sensitive to that intaking into the building." Organizers of the marijuana event decided to move the "smoke-in" from its 20 year home at the Vancouver Art Gallery to the Aquatic Center due to an increase in size. Kirby-Yung said that she encouraged the organizers to choose a different location several months ago. "From the park board's perspective, and I really want to stress this, this is an unsanctioned event, this is a non-permanent event, and it is classified as public protest," she said. "It really doesn't fall under the jurisdiction of the park board." Advertisement The event drew 20,000 visitors last year and cost the city about $93,000, as 64 people were treated at a local hospital. Read More Man calmly confronts suspected car burglar caught in the act on camera Bench facing away from sea reimagined as world's first 'selfie bench' Scottish sonar images reveal Loch Ness Monster, but not the real thing