SALEM, Ore. (AP) — The Oregon Department of Environmental Quality on Thursday issued an air quality advisory for the next several days for parts of southern Oregon that may be impacted by smoke coming from a blaze in Northern California.

Oregon Public Broadcasting reports that Lakeview and Klamath Falls areas fall under the air quality advisory.

Wildfire smoke can irritate the eyes and lungs, and worsen some medical conditions. People it impacts most include infants and young children, people with heart or lung diseases, older adults and pregnant women. The DEQ recommends keeping an eye on the air quality index in your area.

In September, almost all of Oregon was covered in thick layers of unhealthy smoke, as wildfires stretched across the state. Researchers and health experts told OPB that having such high levels of smoke for so many people was unprecedented.

The Lava Fire, which was ignited by lightning last week, has put thousands of people under evacuation orders in Northern California.

As of Wednesday, the fire covered more than 27 square miles (70 square kilometers) but crews “made good progress on the western edge of the fire, cutting off progression into the communities,” Shasta-Trinity National Forest said in a statement.

All evacuation orders issued by the Siskiyou County Sheriff’s Office remained in effect for communities north of the city of Weed, about 250 miles (402 kilometers) north of San Francisco. Residents of other areas were warned to be prepared to evacuate.