Is Air Pollution OK Just Because It’s Wildfire Caused?

Wildfire-caused pollution in Alaska is an annual annoyance like in many regions of the Earth, where fires are part of the landscape evolution. Nature-caused wildfire smoke is often excluded from the determination of the annual exposure to harmful air constituents. Therefore, people living in regions with winter human-caused pollution with summer smoke are reluctant to address the winter air quality problem without also addressing the hazardous air conditions they face on a summer evening after a work day. This post discusses the problem of wildfire smoke that occurs widely in the western US, Canada, Alaska and many other regions in the World each summer. Learn what’s in the smoke, how wildfires have affected Alaska, and how people cope with it.

 

 

Did You Know that Wildfires Are Not a Developing Country Problem?

When I was in elementary school, I loved watching the wildlife documentaries by Bernhard Grzimek. He was a zoo director, and spent time in the Serengeti to film wildlife for the German TV. His documentaries often included scenes of animals running away from wildfires.

As a kid, I thought of these wildfires as a Developing Country issue until the 1976 drought in Germany when the Lüneburger Heide burned. I realized that an extended drought plus a lightning strike and/or human failure can set a fire. Wind and flash-overs spread it. However, a wildfire wasn’t a normal in middle Europe.

 

Interior Alaska Is Wildfire-Prone

Lightning caused wildfires have been a natural and dominant disturbance regime in the boreal forest of the Interior for millennia. The wildfires play an important natural role in its ecosystems. However, in Alaska and Northern Canada, the area of boreal forest burned annually has doubled in the last three decades.

 

 

What Is in the Smoke of Wildfires?

The 2004 wildfire season evidenced that even in a remote and otherwise pristine region like Interior Alaska serious air quality problems can occur. Here, the biomass burning emits carbon monoxide (CO), carbon dioxide (CO₂), methane (CH₄), non-methane hydrocarbons (NMHC), polycyclic aromatic hydrocarbons (PAH), nitric oxide (NO), nitrous oxide (N₂O), carbonyl sulfide (COS), and particulate matter (PM).

 

 

Moreover, wildfires release huge amounts of water vapor (H₂O) because they heat the underlain permafrost, and thaw some of the permafrost. The resulting soil water evaporates or the soil-ice may even directly sublimate to water vapor.

The gases and particles released by wildfires chemically react with trace species naturally available in the atmosphere. Some of the gases photo-dissociate by solar radiation during the long daylight hours and produce free radicals. The emitted gases and radicals also react with VOCs emitted naturally by the deciduous and coniferous trees of the Interior.
Smoke also contain ash that falls out. You can literally see it fall like snowing. The air smells like licking an ashtray. Well, Interior Alaska summers smell like a huge bonfire.

 

 

 

Smoke Reduces Visibility

In the atmosphere, water-soluble particles take up water vapor, and swell thereby reducing the visibility in addition to the ash and non-water soluble particles. When small droplets form, the solution will also undergo chemical reactions.

 

Nature’s Cleansing Processes Can Be a Burden for Ecosystems

The pollutants are removed from the atmosphere by rain, particle sedimentation, and dry deposition of gases. Acid rain is the result of in-cloud and below cloud scavenging of the pollutants. The removal of the pollutants from the atmosphere represents a burden on the ecosystems and natural water systems. Since the peak number of wildfires occurs in summer when insolation and, hence, available energy for photochemical processes is high, the impact on ecosystems and air quality will be the strongest in summer, too.

 

 

A Bit About Air Quality Regulation

For my international readers let me quickly define the US Environmental Protection Agency (EPA) National Ambient Air Quality Standard (NAAQS). The NAAQS for particulate matter less or equal to 2.5 μm in diameter – called PM_2.5 98^th percentile, averaged over 3 years, is 35 μg/m³. Note that PM_2.5 is 70 times smaller than the diameter of a human hair. Various medical publications connected severe health issues to short and long term exposure to PM_2.5. Note that the World Health Organization recommends 25 μg/m³ not to be exceeded.

Particulate matter less or equal to 10 μm in diameter is called PM₁₀. The 24 hours average PM₁₀ NAAQS not to be exceeded more than once per year on average over 3 years is 150 μg/m³. The white and gray ash flakes that you see on our deck in the photo above are greater than several mm (1 mm = 0.0393701 inch).

 

 

Why Is Fairbanks Known as the Nation’s City with the Worst Air Quality?

Huge efforts are made to reduce winter air pollution. In winter, temperatures are so low that nobody gets outside to breath the air. Only at 40 below, Fairbanksans go out in a bikini for a photo which is just 5 minutes or less.

Therefore, people argue that summer air pollution due to wildfires is often much worse than air pollution due to local emission accumulated under the inversion in winter. They argue that their exposure to poor air is higher in summer because they spent more time outside. For instance, they mow their lawn, play, grill, hike, canoe, or just sit on their decks to catch some sun rays to build up their vitamin D levels. Building vitamin D is an urgent need for surviving the winter without getting seasonal depression syndrome or cabin fiver. The smoke from wildfires means that Alaska is no escape from air pollution, i.e., no guarantee pristine air.

 

Smoke Knows No Borders

The wildfire smoke and pollution affects more people than just Alaskans. In the 2004 wildfire season, for instance, the smoke penetrated into Denali National Park, Arctic National Park, the Yukon Flats National Wildlife Refuge, and the Arctic National Wildlife Refuge. In summer, these areas have many visitors. Often smoke from wildfires in Siberia or Canada reaches Alaska.

 

Managing Air Quality in Interior Alaska

Nothing is done against the wildfires. It is just let-it-burn until human life, structure or historic monuments are endangered. This policy is due to the fact that Alaska is only 2% developed. As a result, many areas are wilderness pure. Moreover, reaching the protected areas already makes fire fighting incredibly expensive.

In winter, the air quality officials ask the residents of the Fairbanks metropolitan area to not burn wood when there is a poor air-pollution alert. It’s to protect our health and that’s a good thing! However, what’s the catch? Shouldn’t the fires be fought to protect our health in summer? Long-term exposure can also endanger human life!

 

The 2004 Wildfire Caused Pollution in Alaska Was Hazardous

In 2004, Interior Alaska faced the strongest fire season since onset of recording in 1940. About 6 671 845.3 acres (2 700 000 hectare, 27 000 km²) forests burned. Thick smoke layers of large horizontal and vertical extension covered Central Alaska. On some days, the smoke reduced the visibility to several tens of meters and even led to restrictions on air traffic.

 

 

People wore masks to at least filter out some of the ash, black carbon and other particles. Nevertheless, you could smell the volatile organic compounds (VOC), and the ozone that formed from the precursor gases emitted by the wildfires.

The concentrations of particles with 2.5 micrometer or less in diameter (so-called PM_2.5) were so high that the instrument could not measure them, i.e., over 1000 microgram per cubic meter, which was the uppermost limit the instrument could measure. Note that PM_2.5 concentrations remained at health threatening levels (175 microgram per cubic meter) for several weeks.

Note: The exposure to wildfire caused pollution in Alaska can exceed that caused by emissions in winter.

 

2010 Goldstream Fire

When you already follow this blog for a while, you know that we lived in the Goldstream Valley in our first years in Alaska. The fire in the photos burned in 2010 close to where we had lived. We had seen the fire from far and drove close to it as we still knew a lot of people in our former neighborhood. When we parked at Ivory Jack, the brother of our former landlord was there too. He was one of our closest neighbors back when we lived there. He came to our car and said “Your house is fine and so is everyone. The fire is farther north, and propagates north as well.”

Later in the evening, we met a couple from our former neighborhood at a social dance. “Did they extinguish the fire already?” “Nope. We drove the photos and computers to our children’s house. There is no need to wait until they force us to evacuate. What can we gain by staying at home?” they said, and danced the night away. Thanks goodness their house did not burn down.

 

Example of Air Pollution from Wildfires Near Fairbanks in 2019

In 2019, there were two fires burning in the Fairbanks vicinity. Depending on the wind direction, Fairbanks was under the influence of their smoke. The image below shows the smoke over Fairbanks on June 27, 2019 in the visible range as seen by the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard of NASA’s Terra satellite. There are two large areas of light brown smoke from the Shovel Creek and Nugget Creek wildfires northwest and northeast of Fairbanks, respectively. The red hot spots are heat signatures indicative of fires. Both fires started by lightning strikes. Officials were expecting the fires’ smoke to affect Fairbanks until August when the so-called Alaska monsoon sets in. Note it’s not really a monsoon, but August is the wettest month in the Interior.

 

 

There were firefighting activities in the Murphy Dome area. One of my students and one of my girlfriends as well as several colleagues live in this area. The Nugget Creek fire is 35 miles northeast of Fairbanks around Mile 30 Chena Hot Springs Road in the Chena River State Recreation Area. Some friends and colleagues live in this area.

 

In Alaska, Summer Air Pollution Is Worse Than That in Winter

The diagram below bases on the raw data of the NCORE measurements in Fairbanks downloaded from EPA. You can see the first peak that related to my post on an evening at the Last Frontier. Note that it was called moderate pollution! The pollution went down below the NAAQS when the rain set in and washed out the ashes and particles.

 

 

 

When the Smell of Smoke Wakes You Up and It Is a Normal

Things changed drastically after our move to Alaska. Hazardous smoke annoys in every beautiful summer. You wake up to the smell of fire, close the window, put on the indoor air purifier, turn around, and continued sleeping. After living in the Fairbanks area for more than 20 years, you know that after a week of dry, warm weather in summer, lightning will cause wildfires somewhere, and that the air will smell downwind like you put your nose into an open fire place. You also know that indoor air quality quickly gets as bad as outside.

 

 

 

When a White Night Becomes Dark You Know There Is a Fire

When there is a wildfire, the Sun gets pink (see photo below), and even the street lights with light sensor go on. This really means that the smoke reduces the light. Note that in June, the nights are white, for which typically, no street lights are on. In other words, the ash and PM in the air dimmed the light so strong that the light was pink, and the sensors behaved like they do at dawn: Switch on the lights.

 

 

 

References

Edwin, S.G., Mölders, N., 2020. Indoor and Outdoor Particulate Matter Exposure of Rural Interior Alaska Residents. Open Journal of Air Pollution, 9, 37-60. doi: 10.4236/ojap.2020.93004.

Edwin, S.G., Mölders, N., 2018. Particulate Matter Exposure of Rural Interior Communities as Observed by the First Tribal Air Quality Network in the Yukon Flat. Journal of Environmental Protection, 9, 1425-1448. doi: 10.4236/jep.2018.913088.

Mölders, N., Fochesatto, G., Edwin, S., and Kramm, G., 2019. Geothermal, Oceanic, Wildfire, Meteorological and Anthropogenic Impacts on PM_2.5 Concentrations in the Fairbanks Metropolitan Area. Open Journal of Air Pollution, 8, 19-68. doi: 10.4236/ojap.2019.82002.

Mölders, N., Kramm, G., 2010. A case study on wintertime inversions in Interior Alaska with WRF. Atmospheric Research, 95,  314-332, doi: 10.1016/j.atmosres.2009.06.002

Tran, H.N.Q, Mölders, N., 2011. Investigations on meteorological conditions for elevated PM_2.5 in Fairbanks, Alaska. Atmospheric Research, 99, 39-49. doi: 10.1016/j.atmosres.2010.08.028.

 

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