PORTLAND — The haze from California fires that settled in Oregon over the weekend showed signs of lifting on Tuesday, but health and environmental officials said it would linger several days.

Hospitals in Southern Oregon, where the smoke was heaviest, said they had seen only small increases in the number of people coming to emergency rooms with troubles related to the smoke.

In Eugene, attention was focused on the impact of the smoke on the Olympic trials under way at the University of Oregon, but emergency room Dr. Scott Williams at Sacred Heart Medical Center said it’s been hard to tell the difference between residents suffering from smoke and those suffering from the annual seasonal outbreak of pollen from trees and the region’s grass-seed industry.

“This has been a difficult allergy season,’’ he said.

Particulate measurements at Eugene had been classified as unhealthy as the California smoke began to invade the state, but on Tuesday they dropped to a rating of moderate.

Closer to the Oregon border, and nearer the hundreds of wildfires lightning touched off in California, the emergency room at Rogue Valley Medical Center in Medford hadn’t seen large numbers of people suffering from the smoke.

“Generally, people who have respiratory problems are staying inside,’’ said spokesman Grant Walker.

Oregon and its mountainous southern region often see smoke spreading from wildfires, as in 2002 when the Biscuit Fire burned on 500,000 acres and covered a wide region with smoke.

At mid-afternoon Tuesday, the state Department of Environmental Quality said particulate levels were high enough under federal standards to warrant labeling conditions as “unhealthy for sensitive groups’’ in Bend, Klamath Falls, Medford and Shady Cove. That included people with asthma and heart and lung diseases.

In Oregon itself, federal fire managers reported only three fires, and only one of those of any size, a 30,000-acre blaze in the far southeastern part of the state. California firefighters, however, continued to struggle with hundreds of fires.

The Oregon Department of Environmental Quality said the smoke was spreading to the Salem and Portland areas, as well as southwest Washington. Later in the week, the department said, particulate levels could reach a level that’s unhealthy for sensitive people.

But the haze didn’t seem to interrupt the likes of Portland stockbroker Sam McKinley, 32, one of dozens of joggers in Tom McCall Waterfront Park on Tuesday afternoon. Interrupting a 3.5-mile run, he said he runs most days to deal with the effects of the sell-off in the markets.

“I could stay in the office and be depressed,’’ he said, “or I can go out for a run in the haze.’’

Weather report

Improved air quality in the mid-valley will accompany temperatures cooler than the record-breaking 90s over the weekend.

Today should be mostly sunny with the high again around 85. Evening temperatures will cool to around 56 degrees.

Then on Thursday, the day-time temperature might drop to 82 degrees, and it will be about 77 degrees on Independence Day.