TORONTO -- Despite the Canada-U.S. border being closed to non-essential travel and airlines cancelling international flights into the country, thousands of passengers are still arriving at Canadian airports.

According to new numbers from the Canada Border Services Agency (CBSA), Canada saw a 98 per cent drop this year in travellers arriving from the U.S. during the week of May 18-24.

In 2019, 379,211 travellers from the U.S. entered Canada during that week. This year, that number dropped to 4,077 travellers.

Other international travel saw 12,165 international travellers arrive in Canada by air -- a 97 per cent decrease from last year's total of 388,201. In addition to air travel, Canada also saw 49,785 land travellers enter the country during that week.

John Gradek, a former executive at Air Canada, told in a phone interview on Tuesday that those numbers may seem small in comparison, but they are significant amid the COVID-19 pandemic.

"We are no where near having COVID-19 under control, and there's questions about where these people coming from and what is the state of COVID-19 in those countries," Gradek said. "They're not necessarily coming from hot zones, but they’re definitely coming from some very warm zones."

Gradek, who now teaches aviation leadership and airline management at Montreal’s McGill University, said "a lot of people" are exempt from Canada's border restrictions, including relatives of Canadian citizens, citizens being repatriated, foreign workers and foreign students.

"We have not shut down the borders completely. We are letting people in for a variety of reasons, all of which are good reasons, but the concern that I have is: are [the rules] really being enforced in terms of quarantine," Gradek said.

Under the Quarantine Act, anyone arriving in Canada by air or land must self-isolate for 14 days to help slow the spread of COVID-19. Travellers are also required to complete a contact tracing form at their point of entry so the Public Health Agency of Canada (PHAC) can monitor and enforce the isolation requirement.

Police across Canada have made home visits to nearly 2,200 Canadians to ensure they are complying with their mandatory isolation after returning from abroad. As of May 13, only four people have been ticketed for breaking their quarantines under the federal rules.

Gradek said the number of travellers still arriving at Canadian airports should prompt the federal government to re-evaluate whether more travel restrictions need to be put in place.

"The numbers are significant, but I think it is a question about who the government has exempted from that non-essential travel rule that is causing those numbers to be what they are," Gradek said.

In total, 123,694 passengers from the U.S. and 301,781 international travellers have arrived in Canada by plane since March 21.

While air travel was responsible for Canada's earliest COVID-19 cases, Gradek said it could also play a part in Canada's second wave. To mitigate this, he says a "sanitation standard" needs to be set among all Canadian airports to ensure the same level of disinfection is happening across the country.

"Since the first wave, there really has not been any consistent effort to create a standard in Canada about what's an acceptable level of sanitation that is mandated at airports and on airlines.

"I think there's a need for Transport Canada, if not Health Canada, to step up to the plate and issue conditions and protocols that must be followed by all airports."