WESTPORT — Wildfires ravaging Canada continue to cause sky-high pollution across the northern U.S., prompting an air-quality health advisory from Westport’s Office of Emergency Management on Wednesday.

The unhealthy air conditions — carrying fine particulate matter — may worsen over the course of Wednesday and into Thursday, according to a statement from the state Department of Energy and Environmental Protection.

The National Weather Service has also issued an air-quality alert for the region.

A “significant smoke area moving toward Connecticut from upstate New York and northern Pennsylvania” is being monitored, Westport officials reported about 11 a.m. Wednesday.

As a result, more smoke is expected to move over the Westport region later Wednesday continuing into Thursday, according to the alert.

The town’s schools cancelled outdoor recess activities Wednesday, and planned to cancel all after-school activities, Supt. of Schools Thomas Scarice said.

“We will continue to monitor the situation on a day by day basis,” the superintendent added in reference to ongoing concerns about the wildfires’ impact.

State tournament play for high school athletics has been postponed by the CIAC as a result of the poor air quality. The postponement was expected to affect Staples lacrosse and tennis teams that were scheduled to compete Wednesday. The CIAC plans to reschedule postponed games to Thursday.

Air quality Wednesday already is deemed unhealthy, with the presence of harmful pollutants. “We anticipate the concentration of smoke to be highest [Wednesday night] and early Thursday morning, with lower levels persisting throughout Thursday,” the health advisory warns.

People, particularly those with respiratory conditions like asthma or allergies, should limit time outdoors and stay indoors as much as possible, officials recommend.

Closing windows and doors can help minimize smoke entering a dwelling. Also, consider using air purifiers or set air conditioning to recirculation mode to improve indoor air quality, officials said.