Global pollution levels were down across the board in 2020, reflecting the reality of a pandemic that’s kept people inside and at home instead of commuting to work or heading off on vacations.

IQAir’s annual air quality report for 2020 found that air quality, measured by PM2.5 in the air, in some of the world’s most polluted cities/countries had improved on the whole. Locales across China and South Asia, while still recording numbers in excess of the World Health Organization’s threshold for PM2.5 exposure, showed improvement over 2019.

The same cannot be said for the entire United States. While motor vehicle emissions were reduced as a result of the pandemic, average air pollution exposure levels for Americans were higher than in 2018 and 2019. 38% of US cities failed to meet WHO targets for PM 2.5, down from 21% in 2019 and 20% in 2018. The culprit: a combination of the largest wildfire season on record and rollbacks in environmental regulation coupled with lax enforcement of the Clean Air Act.

In September, 77 of the 100 most polluted cities for PM2.5 in the world were in the United States, per IQAir’s report: 35 in California, 35 in Oregon, and 7 in Washington. The wildfires that burned up and down the West Coast through summer and fall drove pollution levels through the roof in municipalities from Canada to Mexico.

PM2.5 pollution was up 15% in Los Angeles at year’s end, up 35% in San Francisco, 38% in Portland and 53% in Phoenix. 

Comparatively, air pollution fell 13% in Chicago, 9.5% in Philadelphia, and 7% in New York City.

It turns out that the months of brown skies, ash falling on cars, and barbeque-flavored air earned the Eastern Sierra some dubious recognition: Mammoth Lakes ranked fourth on the list of most polluted American cities in 2020, with an average PM2.5 level of 25.6 micrograms per cubic meter. Yosemite Lakes, California topped the list with 37.8 micrograms per cubic meter and Western Sierra cities and towns claimed the top 14 slots altogether. 

Mammoth Lakes recorded the highest pollution levels in the county for September and October 2020 and what saved the town from being higher on the overall list was a run of very clean air for the first seven months of the year.

For reference, the WHO’s target PM2.5 level is anywhere between 0 and 10 micrograms per cubic foot. Anything up to 12.5 is considered “good.” For the rates present in the Eastern Sierra, IQAir writes “general public and sensitive individuals in particular are at risk to experience irritation and respiratory problems” for PM2.5 between 35.5 and 55.4. 

For 55.5-150.4 (“Unhealthy”), the health recommendation is “Increased likelihood of adverse effects and aggravation to the heart and lungs among the general public.”

The Sheet spoke with representatives from the Inyo National Forest and Great Basin Unified Air Pollution Control District (GBUAPCD) to talk about the connection between forest fires and local air pollution and how the two agencies are working in tandem to keep residents safe and breathing easy. 

“Most definitely what we saw last year with, for example, the Creek Fire is not how we want it done,” Inyo National Forest Public Affairs Officer Deb Schweizer said. “Big fires with long term smoke impacts for lots of communities … that’s not the best way to do business if you want good air quality.”

The fire results of 2020 were spurred by 100 years of close mitigation, a process that the Forest Service is working to undo. Regarding controlled burns, Schweizer said, “You’ve got to do it because the more we don’t do it, the more we’ll get [large scale fires].” 

For the most part, the Inyo’s controlled and prescribed burn efforts consists of pile burnings in places like the Lakes Basin, June Lake Loop and Sunny Slopes. Schweizer estimated that the Inyo has done about 1,000 acres of pile burns across the forest. 

The goals are twofold: reduce the risk to the community of an unwanted fire and bolster ecosystem health in an environment that has long counted fire as an essential process.

Ultimately, “The goal is to restore fire on landscape so that it’s acting naturally,” Schweizer explained, “When it’s acting naturally, it’s probably not doing the things we saw last year.”

In discussing the Creek Fire, Schweizer stressed the importance of not losing sight of the wildfire’s destructive path across the Western Sierra and the communities that will be recovering for years to come. But, she added, fire crews working in the higher elevations of the Sierra noted good behavior in that area; the fire break left behind on the landscape will have protective effects for Eastside communities for years to come. 

Phil Kiddoo, Air Pollution Control Officer at GBUAPCD, explained how wildfires can vary in their impacts. For naturally occurring fires, sparked by lightning strikes, the effects can be mitigated by accompanying precipitation or pre-existing burn scars from previous strikes. Those can be a bit easier to predict and prepare for, given knowledge of weather patterns, although abundant fuel can still be an issue.

On the other hand, human-caused fires typically occur during favorable fire conditions (very dry, high winds) and can be harder to predict or pinpoint until the blaze has become sizable. 

Prescribed burns by contrast are much easier to control, as “we know where they’re gonna be, when they’re gonna be, and the amount of emissions”, Kiddoo said. Compared to wildfires, “they’re almost a non-event unless they’re close to a community,” he continued. 

The GBUAPCD works in tandem with the Forest Service to determine when and where to hold these fires, keeping an eye on weather patterns that favor smoke dispersal and discourage rapid spread. 

The Inyo works off of a prioritization list to pick their controlled burns and submits a burn control plan to GBPUACD for any actions it wants to take. The District reviews the plan, submits changes, and “if we aren’t satisfied, then we go back to the drawing board.”

Once the Forest Service is ready to burn, they get the plan to GBPUACD within 72 hours prior, who send it to CalFire incident command once approved. 

“Up until a burn there’s a lot of back and forth,” Kiddoo said, “When they’re going to do that burn and how and what to expect, especially if conditions are not real certain.” If the emissions from the burn cause a notable increase in pollutants, Kiddoo said, then the operation is called off for the day.

The science behind the burns, while educated, isn’t perfect. Kiddoo referenced the recent Taboose fire outside of Big Pine, which began as a controlled burn but ended up jumping fire lines and burning an additional 100 acres of land more than anticipated. 

Given the recent declaration of drought in California by the US Department of Agriculture, the state is poised for another lengthy fire season. 

“The drought is continuing,” Schweizer said,” Yes, this last little plug of snow we got is nice but it doesn’t change the fact that we are in drought conditions.”

As for smoke, “We can say all we want but if there’s fire burning from the Stanislaus [National Forest] to Sequoia [National Forest], we’re going to be impacted,” she concluded.