MONTREAL -- Hundreds of health experts from across Canada are calling for more aggressive measures to stop airborne spread of COVID-19.

The experts include more than 360 scientists, engineers, and doctors who are expressing alarm over surging cases and hospitalizations. They say provincial prevention messages "continue to be deficient" when it comes to infection threats posed by shared indoor spaces.

Their concerns are detailed in an open letter addressed to Canada's Chief Public Health Officer Dr. Theresa Tam, federal Health Minister Patty Hajdu and provincial premiers and medical officers.

They want public health messages to more strongly warn of the risk posed in closed spaces, especially with winter forcing more people indoors.

They're also calling for officials to order the inspection of ventilation systems in schools, long-term care homes and other essential public institutions, and provide funding for necessary upgrades in those spaces.

The World Health Organization and the Public Health Agency of Canada have recognized that COVID-19 can spread by aerosols -- tiny, light particles expelled when people cough, sneeze or breathe that stay suspended in the air for longer periods of time. But the experts say that hasn't resulted in better protective measures for health workers and other essential service workers.

- This report by The Canadian Press was first published Jan. 4, 2021.