It may have started out in jest, but two Canadians are now profiting off a smog "red alert" in Beijing, as Chinese people buy canisters of fresh air from the Rocky Mountains.

From December 8 to December 10, Beijing was under its first-ever red alert — the highest in the four-level system adopted two years ago — for air quality, with children and the elderly being told to stay inside.

The city recommended that schools stay closed, and residents take public transit instead of driving or walking. Those who did step out were encouraged to wear masks — and some turned to ordering the air canisters created by Troy Paquette and Moses Lam.

The pair stumbled into the business venture in 2014 after talking to friends who were frequent visitors to Asia and would tell them about poor air quality in China, specifically.

As an experiment, the two captured as much air as they could in a large Ziploc freezer bag, closed it, and put it on eBay—it eventually sold for 99 cents. Their second attempt started a bidding war, someone bought the bag for an astounding $168, sparking the idea for what's now Vitality Air.

"The way we capture the air now is a bit of a trade secret," Paquette, who goes down to Banff and Lake Louise from Edmonton, Alberta to fill giant cans with air through clean compression, and brings it home to bottle it, told VICE News.

"As much as it started out as a novelty idea, with the really bad smog they've had in Beijing, we're finding people are buying it as more than just a novelty, but for everyday use" he says. "There's been quite a demand."

The canisters have a cap mask attached to it and contain about 150 1-second sprays.

Single and twin packs of cans are being sold from $16 to $46. Aside from China, interest has also come from places like Iran and Afghanistan, said Paquette.

Paquette says it took a while for the product to gain any traction, but since the smog alert issued in Beijing last week, demand has skyrocketed.

Lam told the Telegraph their first shipment of 500 bottles was sold in four days, and a crate containing 4,000 more is on its way to China.

And Paquette said distributors in China have expressed interest in carrying Vitality Air in stores.

But the concept of breathing in air from another location to deal with thick smog isn't completely novel.

For example, to promote tourism in the area and to raise awareness about China's air pollution crisis in 2014, the Laojun Mountain Natural Reserve Development Co. gave residents of Zhengzhou — one of the most polluted cities in the country — a chance to breathe in fresh mountain air from sealed bags.

And Vitality Air isn't the only business capitalizing on the smog. On Monday, a restaurant in Jiangsu Province was caught adding an "air cleaning fee" to customers' bills, some media reported.