Vancouver Coastal Health says the majority of the 220 people who received medical attention at this year's 4/20 marijuana event at Sunset Beach had consumed edibles.

Although there were no serious cases, the number of "green-outs" — the term used to describe nausea, dizziness and general weakness sometimes brought on by cannabis — was up over previous years.

VCH spokesperson Tiffany Akins says people overdose more easily with edibles because there's little quality control or dosing accuracy in many of the products.

She also says because it can take an hour to feel the effects of ingested cannabis, people often make the mistake of not waiting long enough before taking more of the edible, thinking what they've already ingested isn't working.

"That's why we say to people who are going to take edibles, wait until you feel the full effects. The dosage can make a big difference between getting the desired effect versus feeling uncomfortable or anxious or sick," said Akins.

Posters were distributed at 4/20 advising users to wait 20 minutes when smoking cannabis to feel the effects, and at least an hour after ingesting.

VCH staff are working to help make everyone’s 420 celebration as safe as possible, checking on food safety & cautioning vendors on selling to youth. Thank you to the vendors who posted safety signs! <a href="https://twitter.com/hashtag/420day?src=hash&ref_src=twsrc%5Etfw">#420day</a> <a href="https://twitter.com/hashtag/420Vancouver?src=hash&ref_src=twsrc%5Etfw">#420Vancouver</a> <a href="https://t.co/lDKiPrgPLj">pic.twitter.com/lDKiPrgPLj</a> —@VCHhealthcare

VCH says 35 people were treated at St. Paul's emergency department with more serious problems, including four underage patients. Another 185 were treated by medical teams contracted to staff the 4/20 event.

The estimated crowd of 40,000 was the largest ever at the Sunset Beach 4/20 event, up from 35,000 last year and 25,000 in 2016.