PENDLETON — The smoke has finally cleared from the two wildfires that broke out mid-month.

The nearly 17,000-acre Hat Rock Fire near Hermiston and roughly 500-acre Mount Hebron Fire near Pendleton left surrounding communities shrouded in smoke.

It’s yet another early start to fire season — not the first in recent years as summer skies have become increasingly overcast and hazy with smoke due to wildfires burning somewhere, whether near or far.

The Oregon Department of Environmental Quality released a report in May titled “Wildfire Smoke Trends and the Air Quality Index,” which corroborates the earlier starting and longer running wildfire seasons the state has been experiencing in recent years. The report tallies and summarizes Air Quality Index data for 24 Oregon communities. Specifically, it looks at the number of days the AQI registered “unhealthy for sensitive groups or worse” (≥USG) during the summer wildfire season.

The report’s key finding was “Wildfire smoke impacts are increasing across the state. There are more ≥USG days per year and more years with at least one ≥USG event.”

The report noted these ≥USG events began increasing around 2012.

Data collected by DEQ for Pendleton, which goes as far back as 1999, reveals a spike in ≥USG days starting in 2015. Two years later saw the most ≥USG days with seven at USG, two ranked Unhealthy and one Very Unhealthy. 2020 was the worst year on record with less total days, but more severe conditions with one Unhealthy day, three Very Unhealthy and four Hazardous.

As Ed Townsend, science and operations officer at the National Weather Service in Pendleton, explained, “Pendleton saw an increase of around 29-fold in the number of days between 2017-22 versus the entire 1999-2016 period, or a total of 35 days with AQI unsafe for sensitive groups or worse.”

Townsend’s office works with DEQ to evaluate and model how weather conditions influence the movement of smoke, allowing DEQ to forecast upcoming air quality conditions.

La Grande has seen a lot more ≥USG activity over the years, with a handful of ≥USG days prior to 2012. 2015 saw a spike that has now become a new norm for wildfire season. Hermiston was not included.

The report’s authors predict “if these trends continue, Oregon should expect to see an increasing number of days with an AQI ≥USG during the summer.”

Causes“Where there’s fire, there’s smoke,” said Laura Gleim, DEQ public affairs specialist for the eastern Oregon region, explaining, “The years with the poorest air quality correlate with larger numbers of acres burned.” That includes fires burning thousands of miles away whose smoke drifts into the region on wind currents.

The National Interagency Fire Center has said forest fires in recent years have become more massive and burn more acres on average.

The Oregon Global Warming Commission has tracked an upward average trend in temperatures over time, with many of the hottest years on record coinciding with the years of greatest uptick in ≥USG days.

Though global warming trends are an ongoing study, climate change does gradually shift seasonal weather patterns. Hotter seasonal weather patterns lead to a warmer dry season, changes in vegetation growth, changes in land use and fire fuel availability.

“With drought, that will create ideal conditions for fires, making it easier for fires to spread whether they’re caused by lightning or human error,” said Townsend.

“Total annual area burned in Oregon has increased during the last 35 years. As aridity increases, the likelihood of extreme fire weather is increasing, and the area burned by lightning-caused fires in central Oregon is projected to increase,” stated a 2023 executive summary of the Oregon Climate Change Research Institute’s biennial climate report.

Townsend pointed to the recent Hat Rock Fire as a prime example of the way weather patterns can set the stage for more severe wildfires.

An early heatwave settled in across the region in May. On May 20, the daytime high hit 97 degrees Fahrenheit, which broke the previous record high. Townsend said the average high is 77 degrees for that time of year with 97 more commonly seen at the end of July.

On June 12, when the fire broke out, the National Weather Service declared a Red Flag Warning for the day due to the relative humidity being between only 20-25% with strong winds and high gusts in the forecast. At around 11 a.m. when the fire started, wind speeds were around 23-28 mph and peak gusts occurred between 4 and 6 p.m. at 47 mph.

Compounding the situation, Townsend said conditions on the ground were extremely dry. “Last time it rained in Hermiston, they received 3/100 of an inch on (May) 9th. The last measurable amount was in early May, a ½ inch below average for the month.”

It’s often said wildfires create their own weather; a lot of that phenomenon is influenced by smoke, according to Townsend.

Smoke can temper high air temperatures by blocking sunlight, causing the solar radiation that heats the earth to be reflected back by particles that make up smoke instead of being absorbed.

Thanks to this quality, dangerous particles in wildfire smoke likewise get trapped by the pseudo cloud layer at night.

“The warmer air stays on top (of the smoke), while it’s cooler on the ground surface,” Townsend explained. “Wildfire pollution can get up and out of those lowest levels closest to the earth during the day, but at night it gets trapped because warm layers form above the cool air … that is a huge indicator of if the AQI will be poor or not.”

How to prepareWildfire smoke is a cocktail of harmful chemical compounds such as carbon monoxide, volatile organic compounds, black carbon, polycyclic aromatic hydrocarbons, heavy metals, nitrogen dioxide, ozone and particulate matter 2.5 (PM2.5) and PM10. Some of these can reach the bloodstream if inhaled.

Though at ≥USG, the general public is not likely to be affected, at Unhealthy and above, everyone may begin to experience health effects, and the Hazardous level constitutes emergency conditions.

Watery eyes, respiratory tract irritation and headaches are common effects of exposure. Oregon DEQ advises the best way to protect oneself from wildfire smoke is to stay indoors when air quality is poor and filter indoor air using high-efficiency particulate air — HEPA — filters in indoor ventilation systems and portable HEPA air purifiers, just be sure the latter are appropriately sized for the room.

Gleim added exterior doors and windows should be kept closed. The air recirculation function on some home air systems and cars can also help.

Joe Fiumara, director of the Umatilla Public Health Department, said his office encourages people to plan ahead of wildfire season and keep extra filters for furnaces, box fans, air purifiers and masks on-hand, because they can be hard to find once an event has started.

He added that those who have to go out or work in unhealthy conditions should wear a properly fitted and sized N-95 or P-100 respirator to mitigate exposure. Regular cloth or paper masks are not sufficient to block wildfire smoke. Fiumara emphasized that respirators don’t completely eliminate exposure, but can reduce it.

Fiumara also said people should avoid activities that increase respiration, including exercise, until air quality improves to minimize inhalation of contaminants.

Nathan Wadsworth, assistant chief nursing officer at Grande Ronde Hospital in La Grande, said dangerous health symptoms one should seek medical attention for immediately include: difficult labored breathing, chest tightness, feeling like it’s taking longer to recover after exertion, tingling lips, dizziness or confusion.

The Air Quality Index consists of six color-coded levels of advisory based on a measure of air pollutant concentrations, including particulate matter 2.5 (PM2.5), ozone, PM10, nitrogen dioxide, carbon dioxide and sulfur dioxide.

The six levels are: Good (green), Moderate (yellow), Unhealthy for Sensitive Groups (orange), Unhealthy (red), Very Unhealthy (purple) and Hazardous (maroon).

“Sensitive groups” include people with heart or lung disease, asthma and other respiratory issues, pregnant women and children whose rate of breathing and smaller developing respiratory systems put them at risk.

You can monitor air quality on the Oregon Smoke Information Blog, Oregon Department of Environmental Quality’s AQI website or by downloading the free OregonAIR app.

“Wildfire pollution can get up and out of those lowest levels closest to the earth during the day, but at night it gets trapped because warm layers form above the cool air … that is a huge indicator of if the (Air Quality Index) will be poor or not.”

— Ed Townsend, Northwest Weather Service in Pendleton