Smoke from wildfires burning in Canada prompted the Pennsylvania Department of Environmental Protection to issue a statewide Code Red Air Quality Alert Wednesday.

The alert, which means that air pollution concentrations may be unhealthy for some, was in effect until midnight Thursday.

But AccuWeather meteorologist Isaac Longley doesn’t expect the smoke and haze to immediately clear.

Forecast models are showing smoky conditions lingering in the lower levels of the atmosphere through Friday.

“Smoke at the lower levels is what causes air quality concerns,” he said. “That is what we are dealing with again. It is similar to what we saw a few weeks ago. Unfortunately, that seems to be common this summer.”

Longley, who is based in State College, Centre County, reported that hazy conditions were more intense there Wednesday morning.

“You could barely see the ridgelines and ridges,” he said. As the day wore on, the haze began to dissipate - and move east to places like Carbon and Schuylkill counties.

Across the region, Wednesday’s skies were mostly cloudy during the day. Toward the evening hours, peeks of sun broke through - and the smoke and haze became more apparent.

“There will likely be a Code Red issued for Thursday and it could be a problem even into Friday,” Longley said.

In early June, smoke was particularly heavy in the area, prompting the DEP to issue Code Red warnings on several days.

People with heart or lung disease, older adults, children and teenagers, and outdoor workers might experience more serious health effects by breathing the polluted air. The effects can be minimized by avoiding or reducing long or intense outdoor activities.