Open this photo in gallery Mask-clad commuters make their way to work during the morning rush hour at Shinagawa train station in Tokyo on Feb. 28, 2020. The World Health Organization and other provincial governments say mounting evidence shows the new coronavirus spreads through droplets such as sneezes, not through the air. CHARLY TRIBALLEAU/AFP/Getty Images

Nursing unions are demanding higher standards for the protective gear their members wear while caring for suspected coronavirus patients, but some infectious-disease experts say the unions’ plea isn’t backed by science and could lead to shortages of crucial supplies.

The Canadian Federation of Nurses Unions, an umbrella organization representing unions in eight provinces, asked its members on Friday to send letters urging their provincial health ministers to adopt safety measures that would protect health workers from airborne viruses.

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The CFNU’s position is in lockstep with the Province of Ontario and the U.S. Centers for Disease Control and Prevention, but out of step with advice from the Public Health Agency of Canada, the World Health Organization and other provincial governments who say mounting evidence shows the new coronavirus spreads through droplets such as sneezes, not through the air.

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“We need to step it up,” said Linda Silas, president of the CFNU. “[Federal Health Minister Patty Hajdu] is advising families to get ready with their food and water and medication. Well, that’s nice, but our health-care system is not ready right now and we need to get ready.”

The debate about how best to shield Canadian health-care workers has intensified as the new coronavirus has spread to nearly 60 countries, infecting more than 84,000 people and killing more than 2,800.

On Friday, Ontario confirmed a new case of COVID-19, as the disease caused by the new virus is known.

The patient, a man in his 50s, returned from Iran on Tuesday and visited the emergency room at Toronto’s Sunnybrook Health Sciences Centre on Wednesday. He is now in self-isolation at home, public health officials in Ontario said.

Open this photo in gallery Pedestrians walk in the Chinatown district of downtown Toronto, Ontario, after 3 patients with novel coronavirus were reported in Canada January 28, 2020. CARLOS OSORIO/Reuters

Canada had logged 16 cases of COVID-19 as of Friday night, seven in British Columbia, eight in Ontario, and one presumptive positive case in Quebec. All the cases could be traced to China, where COVID-19 emerged, or to Iran, the site of the deadliest outbreak outside of China.

Still, public-health officials fear more COVID-19 cases could be lurking undetected in Canada.

In the coming days, Ontario is launching a “sentinel surveillance” program to randomly test some patients admitted to hospital with respiratory illness for the coronavirus – even if they haven’t travelled to China or one of the countries battling a big outbreak, such as Italy, Iran or South Korea.

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Ontario is also expanding its testing capacity, with public laboratories in Hamilton, Kingston and Ottawa preparing to test for the new virus by the middle of next week, according to Vanessa Allen, chief of medical microbiology at Public Health Ontario’s laboratory.

“We’re ramping up very aggressively," she said. "We’re aiming to do, in very short order, about 1,000 tests a day.”

The CFNU’s position on protective gear for health workers differs from what all provinces but Ontario are doing in one critical way: the use of disposable respirator masks called N95s.

Open this photo in gallery Chief Public Health Officer of Canada Dr. Theresa Tam speaks at a press conference in Ottawa, on Sunday, Jan. 26, 2020. Justin Tang/The Canadian Press

The nursing organization says hospitals across the country should adopt airborne precautions that would require health-care workers treating patients with suspected or confirmed cases of COVID-95 to don fit-tested N95 masks.

The CFNU also wants to see workers wear powered air purifying respirator masks and full-body protective equipment when performing “aerosol generating” medical procedures, such as bronchoscopies, when a small scope is inserted into the lungs.

By contrast, the Public Health Agency of Canada and other provinces say paper surgical masks are sufficient for protecting health-care workers from the coronavirus most of the time, and that N95s should be reserved for aerosol generating procedures.

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Allison McGeer, director of the infectious diseases epidemiology research unit at Mount Sinai’s Lunenfeld-Tanenbaum Research Institute in Toronto, said health-care workers should use what are known as droplet precautions, including the use of regular surgical masks, eye guards, gloves and gowns when treating coronavirus patients.

Open this photo in gallery A researcher works in a lab that is developing testing for the COVID-19 coronavirus at Hackensack Meridian Health Center for Discovery and Innovation on February 28, 2020 in Nutley, New Jersey. Kena Betancur/Getty Images

Unlike small airborne particles, COVID-19 droplets are large and will land on a health-care worker’s surgical mask, protecting them from infection, she said.

The fast-moving coronavirus outbreak is leading to growing concerns of a worldwide N95 shortage, highlighting the need to use them judiciously, Dr. McGeer said.

“It’s pretty easy to generate a shortage of [N95] respirators,” Dr. McGeer said. “It’s not easy to increase production of them, just because of how they’re made, and I think there’s a legitimate concern about countries shutting down exports of respirators.”

Canada’s deputy chief public health officer Howard Njoo told reporters Thursday that infectious disease and emergency room physicians have warned federal officials about a possible shortage of N95 masks.

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He said droplet precautions are needed to help protect workers and manage resources.

Ms. Silas called that view “nonsense.” If hospitals began to run out of N95 masks, union leaders would work with hospitals to reserve the masks for workers who need them most, she said.

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