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Smoke enveloped Klamath Falls Monday afternoon. Klamath County Public Health and the Oregon Department of Environmental Quality expect that it'll be here to stay for at least the rest of the week. H&N Photo by Alex Schwartz

Smoke from the Caldwell Wildfire Complex descended into the Klamath Basin on Monday, tanking the area’s air quality. The Oregon Department of Environmental Quality issued an air quality advisory for Klamath County on Tuesday morning and expects it to last until Friday at the earliest.

Between 4 and 5 p.m. Monday afternoon, the ODEQ’s air monitoring station in Klamath Falls recorded an Air Quality Index increase from 63 to 183—from “moderate” to “unhealthy.” AirNow, which pools together AQI data from various government agencies, reported a “hazardous” AQI of 313 at 7 p.m. Monday.

Tulelake, which lies just north of Lava Beds National Monument where the fire is taking place, was covered in a fog-like smoke Tuesday. The DEQ station in Chiloquin recorded air quality that was “unhealthy for sensitive groups” for most of Monday evening and Tuesday morning.

Through Tuesday afternoon, AQI in Klamath Falls continued to remain above 100, the national air quality standard set by the Environmental Protection Agency above which indexes are considered unhealthy.

Valeree Lane, public information officer for Klamath County Public Health, said weather and fire intensity caused the abrupt influx of smoke to the basin.

“Because the basin is bowl-shaped, when we have a wildfire incident, it’s not uncommon for us to get a shift of wind and to have smoke just all of a sudden appear,” Lane said.

That wind came from a low pressure system currently out in the Pacific, which pushed air in the basin downward—and the smoke along with it. That system is projected to remain intact for the remainder of the week, leading to smoke in the forecast through Friday. How intense that smoke is depends largely on how the fires fare over the coming days.

While agencies determine AQI based on the concentrations of several types of compounds in the air, smoke events from wildfires concern particulate matter smaller than 2.5 micrometers (PM2.5). Thirty times thinner than a human hair, these microscopic particles can be absorbed by the lungs to cause respiratory problems. They can even enter the bloodstream and affect the heart, making them more detrimental to people with preexisting respiratory or cardiovascular conditions. Smoke can also irritate the eyes and cause reduced road visibility.

According to a news release from Klamath County Public Health, older people, pregnant people and those with preexisting conditions are most at risk for negative health effects from wildfire smoke. Children may also be disproportionately affected, as their airways are still developing and they breathe in more air per pound of body weight than adults do. But when AQI is above 151, EPA standards say the entire population could be affected, not just the especially vulnerable.

Lane said it’s crucial to stay inside during smoke events that pose such elevated health risks. While getting out of town and up into the mountains that form the rim of the “bowl” the smoke has spilled into, she said pandemic-related travel restrictions make that less realistic. KCPH suggests that residents stay home, keep their windows and doors closed and install a HEPA air filter if possible. Pets should also be kept inside, Lane said, as anything that breathes will be impacted by the smoke.

While face masks are a key tool in controlling the spread of respiratory illnesses like COVID-19 and have thus become a part of daily life in 2020, Lane said not all types will protect our lungs from smoke. N95 masks, when properly fitted and sealed around a person’s nose and mouth, can filter out PM2.5 particles, but they’re being reserved for healthcare workers treating COVID-19 patients. Other face coverings, like those made out of cloth, aren’t as selective. Their looser stitching may catch a COVID-infected respiratory droplet, but smoke can still get through.

“There’s no science that says that cloth face coverings can help with smoke when you’re outside,” Lane said. Even dust masks can’t catch the tiny particles floating around in smoke—the surest way for residents to protect themselves from respiratory trouble this week is to stay inside.

ODEQ posts air quality updates every hour to their interactive air quality map, available online or through the free OregonAIR app. The U.S. Interagency Wildland Fire Air Quality Response Program also tracks the air quality of cities associated with major fires.