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The signs sprouting up near border crossings and in airports across Canada are clear.

Paraphrased: Don’t take your pot to the States, or other countries which aren’t Canada.

Here’s one that recently appeared at Saskatoon’s airport:

This sign is displayed in front of the airport security check-in at the Saskatoon airport.

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Having got the message, it’s less clear what the traveller is supposed to do next.

After legalization, adults will be free to take up to 30 grams — roughly a double handful — on domestic flights.

Why might you want to? Cannabis will be much more available in some provinces than others for a while after legalization, and while you can’t mail-order your pot from other provinces, you can buy it in person and bring it home, assuming you can find a retail outlet that can sell it to you.

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But international flights are another matter entirely.

“More than the United States, I’m concerned about countries like China, South Korea and Saudi Arabia that have direct flights from Canada, in some cases, and that could cause significant risks to Canadians that could travel with cannabis,” said Deepak Anand, an executive at Cannabis Compliance Inc., a consulting company.

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“The consequences are quite serious.” Tweet This

Airports in the U.S. where recreational pot is legal have installed “amnesty boxes,” or containers where people can abandon cannabis that won’t be legal at their destination.

The boxes at the Colorado Springs airport have been in use since 2014, when the state legalized recreational marijuana. (Before that, panicking travellers resorted to flushing and even burying their pot, which was a nuisance for the airport.)

The Las Vegas airport’s versions are bolted to the floor and set up to make it hard to reach for the contents, much like a mailbox. The airport’s 13 boxes are emptied twice a week, and none is ever empty.

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Without amnesty boxes, though, the signs in Canada’s airports just point out a problem to travellers, without giving them a way of solving it.

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“There isn’t really a correct or proper way of disposing of it other than throwing it into the random garbage bins that are at the airport,” Anand says.

Anand noticed the problem last week at the Vancouver airport, where signs recently went up just before security warning people not to take marijuana on international flights.

“There clearly needs to be a more formal way to handle it. A couple of amnesty bins around the airport are probably a really good idea.” Tweet This

The Las Vegas airport spent $114,000 (U.S.) to install the bins and have a company empty them for a year.

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The Vancouver airport declined an interview request.

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Toronto’s Pearson International Airport hasn’t made a final decision about amnesty boxes, said spokesperson Natalie Moncur.