Ted White strolls the sidewalk on the north side of Auburn Avenue on a morning that more resembles London cloaked in its famous autumn fog than Baker City on the final week of summer.

But the gray cloud that draped itself over Baker City Wednesday morning carried not the salty tang of the sea but rather the acrid scent of scorched wood.

For the fifth straight day, smoke from the massive and destructive fires on the other side of Oregon and from Northern California, propelled by upper level winds, sullied the sky in Baker County and most of the rest of the state.

The smoke dirtied the air to potentially dangerous levels, blocked views of the nearby Elkhorn and Wallowa Mountains, and deflected some of the sun’s power on what would otherwise have been an unseasonably hot and possibly record-setting day.

But the smoke didn’t discourage White, of Baker City, from taking his daily walk.

He planned to put in about 3 miles on Wednesday.

White said the smoke is a “nuisance.”

But only once during the current spate of smoky days has the air been so foul as to drive White indoors.

“Other than that it hasn’t bothered me,” he said.

For much of last week Baker County was largely spared the onslaught of smoke from record-setting wildfires in the western and southern parts of Oregon that have burned more than 1 million acres.

But late in the week the upper level winds shifted to westerly, and the smoke spread across Oregon east of the Cascades.

The air quality index in Baker City — the sensor is on the roof of the David J. Wheeler Federal Building at 1550 Dewey Ave. — has exceeded the “moderate” category consistently since the first hour of Saturday, Sept. 12.

Since then the index has ranged from 116 to 257, at various times in the “unhealthy for sensitive groups,” “unhealthy” and “very unhealthy” categories.

The air quality index has six categories:

• 50 and under, “good” (green)

• 51 to 100, “moderate” (yellow)

• 101 to 150, “unhealthy for sensitive groups” (orange)

• 151 to 200, “unhealthy” (red)

• 201 to 300, “very unhealthy” (purple)

• 301-500, “hazardous” (dark red)

The dangerous components of the smoke are “particulate matter,” said Dr. John East, a pulmonary and critical care physician at Saint Alphonsus Medical Center in Boise.

These particulates, which include fragments of wood and other material that burned, are so small that they can infiltrate deep into the lungs, causing inflammation, East said.

Smoke particulates tend to be less than 1 micrometer in diameter, compared to a human hair at about 60 micrometers, according to the U.S. Environmental Protection Agency.

People most susceptible to the harmful effects of wildfire smoke are those who have existing lung diseases such as asthma and chronic obstructive pulmonary disease (COPD), East said.

When the air quality index reaches the “unhealthy for sensitive groups” category or above, people with those conditions are vulnerable not only to having their existing ailments worsen, but they’re at a higher risk for viral respiratory infections.

The coronavirus, for instance.

“Right now that’s particularly pertinent,” East said.

Even people who don’t have existing respiratory problems and are otherwise healthy should limit their outdoor activities — especially stressful ones such as running or bike riding — when the air quality index rises to the “unhealthy” or red category, East said.

“Even healthy populations can end up being impacted,” he said. “It would be best to curtail those high-exertion activities when it’s in the red range.”

On the positive side, East said short-term exposure to wildfire smoke, even extending for a few weeks, doesn’t lead to long-term effects.

The current situation is not comparable to, say, smoking cigarettes for a decade.

Although it has the potential to cause or exacerbate breathing problems, the thick smoke could have one beneficial effect for people who spend a lot of time outside — cooler temperatures.

The smoke layers, which have extended as high as 15,000 feet in altitude, said Jay Breidenbach of the National Weather Service in Boise, block some solar radiation.

The weather pattern this week, without the insulating effects of the smoke, would yield high temperatures in the 90s at lower elevations of Baker County, according to the Weather Service.

Those would threaten to set daily records for mid-September. The record highs at the Baker City Airport for this week range from 92 to 95.

But the smoke trims at least several degrees from the high temperatures, and in some cases even more, according to the Weather Service.

The highs this week at the Airport, from Saturday through Tuesday, were 78, 86, 91 and 85.

In the forecast discussion Wednesday morning, the Weather Service’s Boise office, which issues forecasts for Baker County, noted that the smoke is “reducing temperatures around 10 degrees and keeping the region from reaching record high temperatures today and Thursday.”

Baker Valley farmer Mark Ward, whose family raises several crops, said the smoke would have affected yields had it arrived in July or August during the height of the growing season.

But with only potatoes and silage corn yet to harvest, Ward said those crops are mature enough that the smoke, and its reduction of sunlight, won’t harm them.

The smoke will slow the drying process for alfalfa hay, however, Ward said.

That tends to be a challenge for the final cutting of the season in any case due to the longer, cooler nights with heavy dew and the potential for frost.

Ward said Baker Valley had a frost last week, when skies were clear but smoke-free.

The low temperature dipped to 29 degrees on both Sept. 10 and 11 at the Baker City Airport.

Ward said the smoke doesn’t bother him, but he has an employee who has more trouble breathing when the smoke is thick.

A cold front forecast to move through Baker County Friday morning could at least temporarily dissipate some of the smoke, according to the Weather Service.

The front could bring showers or thunderstorms, along with stronger northwest winds that could combine to clean the atmosphere, at least partially.