Smoke from wildfires in the western United States has spread east, raising pollution levels as far as the Great Lakes region, according to the National Weather Service.

In California’s North State, pollution levels are unhealthy to very unhealthy, and the hazy skies will be around for most of the week. What’s more, an air quality advisory is in effect for the entire state of Oregon through Thursday.

Redding’s levels dropped into the high unhealthy range Monday morning, according to the EPA’s AirNow air quality index (AQI).

Conditions could worsen again if the smoke thickens, according to a Shasta County air quality advisory.

Some areas of the county may see more smoke and pollution than other areas depending on how close they are to wildfires, and depending on current weather conditions, Shasta County Air Quality Management District officials said.

Air pollution levels in Mount Shasta and Yreka also were considered very unhealthy on Monday, a range sustained daily since Friday, according to Air Now.

Right now, “we have really crappy air,” Siskiyou County air pollution control office Jim Smith said. “In places, it has been very hazardous since the Red Salmon Fire started.”

People should avoid areas with active fires throughout the North State, like Happy Camp, Smith said.

California wildfires: Critical fire weather forecast for area of North Complex; fire now 26% contained

Light winds every day this week, and gusty winds predicted Thursday, may move the smoke, according to a forecast from the National Weather Service in Sacramento.

“The bad news for Redding is it will be southerly winds (during the day), pushing smoke from the August Complex north,” NWS meteorologist Cory Mueller said.

At night, winds going south will likely push smoke from fires in Oregon and Northern California over Mount Shasta and into Shasta County, Mueller said.

Strong wind gusts predicted Thursday, together with dry fuels, could spread current fires and enable the start and spread of new ones, according to Monday’s NWS forecast.

Until the smoke clears and air quality improves, people with respiratory or heart disease, the elderly, pregnant women and children should reduce their time, and avoid when possible, going outside, the advisory said. Everyone else should limit prolonged exertion. When possible:

Limit exercise and outdoor activities.

Remain indoors with the windows and doors closed.

Turn on an air conditioner with a recirculation setting, such as in a vehicle.

The Shasta County Air Quality Management District operates air quality monitors in Anderson and Redding that read pollution levels in the area.

Siskiyou County has permanent monitors in Yreka and Mount Shasta.

Both counties have numerous portable sensors positioned throughout their areas.

As of Saturday afternoon, wildfire smoke reached as far east as Michigan, according to satellite imagery taken by NWS meteorologists in Maryland and posted on Twitter. 

Wildfire smoke reaches Michigan; North State air hazardous to breathe