VANCOUVER -- Acknowledging a problem with outbreaks impacting B.C. workers, the province's top doctor announced a new public health order Thursday.

Calling it an "expedited workplace closure order," Dr. Bonnie Henry said this new measure will allow WorkSafeBC inspectors to shut down a workplace for a period of 10 days or longer, if needed, after COVID-19 transmission is detected.

Part of the reason behind the new order is an increase in transmission among working-aged adults.

"I don't need to tell people that we have also seen new cases in younger populations, particularly the 20- to 39-year age group, and much of it is being driven by our social interactions, and then amplified in places like work places," she said during a news conference.

"Those gatherings with different people in different places on different days are fuelling the spread of the virus that we're seeing."

The order falls under the Public Health Act, Henry said, and will be used with guidance from medical health officers in cases of workplace transmission.

"When three or more workers have COVID-19 at a workplace, that's determined by public health to be transmission in that workplace," she said.

"We have an outbreak protocol that includes testing, that includes investigation of how transmission might happen."

When it's determined that transmission has occurred, the workplace can be shut down under the new order.

Depending on the situation, this type of shutdown may only involve one particular location or team. Using the example of a construction site, Henry said there may be cases where just one team on site needs to be off for a period of time.

When a closure is ordered, WorkSafeBC will work to support public health, serving the closure notice and supporting a review of existing safety plans.

"We recognize, of course, there are many workplaces that cannot be closed… those will be under the guidance of public health as well," she said, listing police stations and health-care facilities, among other examples.

"But we now have some extra resources to help support those workplaces when we have workplace transmission and worker safety is at risk."