Wildfires in California, Oregon and Washington in September burned with such intensity that plumes of smoke billowed across the country, over the Atlantic Ocean and into the atmosphere above Europe, more than 5,000 miles away.
Closer to the flames, downwind communities were inundated with smoke and ash from burning trees and buildings. Smoke from several fires blew into the wide San Joaquin Valley, and a thick haze pooled on the Valley floor for weeks.
Even in a good year, cities in the Valley often have the worst air pollution in the nation, contributing to high rates of asthma, Chronic Obstructive Pulmonary Disease or heart disease. Pollution often sits stagnant on the Valley floor that’s surrounded on three sides by mountains.
This year, during California’s worst wildfire season on record, there were days — even weeks — of some of the highest levels of air pollution ever measured locally, reaching unhealthy and even hazardous levels.
Inhaling wildfire smoke has been compared to smoking cigarettes. It’s especially dangerous for children and older adults.
For nearly two months, the air carried fine particles that can trigger asthma attacks, cause permanent lung damage or even death. Residents were told to avoid prolonged outdoor activities. It was dangerous for children to be outside. A quick escape wasn’t available; On 10 different days, the air was unhealthy everywhere in the Valley.
It was a public health emergency (on top of the COVID-19 pandemic), and predictive models suggest it will happen again.
A record year for California wildfires, air pollution
The health risk comes from microscopic particles known as PM 2.5 that are 30 times smaller than the width of a human hair. At this size, PM 2.5 can travel through the respiratory system’s natural defense barriers and into the heart, lungs and bloodstream.
The federal health standard for PM 2.5 is 35 ug/m3 (micrograms per cubic meter of air) averaged over a 24-hour period. During the Creek Fire, the 24-hour average reached almost 200 micrograms in Clovis, Fresno and Madera.
That’s five to six times the federal limit.
In some hours on the worst days, the concentrations of PM 2.5 reached hazardous levels. Sept. 14 was particularly bad; levels of PM 2.5 were over 300 ug/m3 in Madera and Clovis.
“It’s pretty telling of just how bad these high concentrations were,” said Jon Klassen, director of air quality science and planning with the San Joaquin Valley Air Pollution Control District.
“We’ve seen levels like that before (during past fires.) But what was unique this time, was we saw levels like that across the entire San Joaquin Valley. The entire Valley was inundated with smoke,” he said.
A growing body of research links exposure to wildfire smoke with increased hospitalizations and death from respiratory failure, including increased asthma diagnosis. Local hospital records aren’t yet available for that time period.
A study of Medi-Cal records during the San Diego 2007 wildfires found increased emergency room visits and hospital admissions for infant and young children. Of particular note, was a 243% increase in asthma diagnoses for infants in the days during and following the wildfire.
The Valley, at times during this wildfire season, seemed surrounded by fire.
An estimated 4.2 million acres burned during the 2020 wildfire season, breaking the previous record in 2018 of 2 million acres. It wasn’t just the scale of a few fires that caused problems, but the number of intense fires.
“The wildfire season in 2020 broke a lot of records in California,” Klassen said.
Six out of 20 of the largest fires in California history were in 2020.
Shifting winds rarely brought clarity, only smoke from a different fire. Smoke from the August Complex Fire and SCU Lighting Complex Fire was pushed south by northern winds, while eastern winds brought smoke from the nearby Creek Fire — all blew through the Central Valley.
Air quality violated federal health standards in at least one San Joaquin Valley town nearly every day between mid-August and mid-October, according to data from the California Air Resources Board.
Local air pollution regularly nears the federal limit during winter, when exhaust from cars and trucks, dust from agriculture fields and emissions for polluting industries is trapped on the valley floor by geology, topography and weather patterns.
Still, smoke from the 2020 fires dwarfed those pollution levels.
More fires, more asthma in coming years
Breathing wildfire smoke can be dangerous for anyone, but there are ways for people to protect themselves by avoiding outdoor activity or wearing N-95 masks when the air is bad.
That was a difficult ask for people who were already spending more time at home because of the coronavirus pandemic. During bad air days, people still went running or took their kids to the park.
The San Joaquin Valley Air Pollution Control District is the public health agency tasked with alerting residents of the risks. The agency did see an increase in number of subscribers to its air quality alert system during the wildfires.
During the wildfire season, the agency said they issued press releases, gave media interviews about changing air quality levels, worked with the National Weather Service to get air quality alerts and held live press conferences.
Chief communications officer for Valley Air Jaime Holt said staff are working to think of new or better ways to communicate the risks to the public.
This year the team did more Spanish language outreach and increased social media presence to include Nextdoor in response to public feedback, Holt said.
The need to communicate the risk will likely grow in coming years, as prolonged droughts caused by climate change are expected to increase the risk of wildfires in California.
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That’s explained in a recent report by Union of Concerned Scientists about climate change impacts in the San Joaquin Valley.
“The warming of the Earth reduces the moisture in the soil, increases evapotranspiration (water used by plants and evaporated from rivers and lakes), and speeds up the melting of snow and ice. Scientists also expect that the rainy season will become shorter.”
“These changes facilitate the conditions for droughts and will increase their severity and frequency. Increasingly dry forests, grassland, shrubs, and other vegetation means increased fuel for intense wildfires,” the report says.
Because of that, public health officials predict asthma events from smoke exposure will increase in the next few decades, costing millions of dollars in medical costs.