Wildfires Plus Heat Make Breathing Dangerous in America’s West

Written by Amy Norton HealthDay Reporter >

A new study warns that wildfires and rising temperatures are exposing more and more Americans to a double whammy of smoke and smog, Wednesday, January 12, 2022.

Researchers have found that over the past 20 years, an increasing number of people in western states have been simultaneously exposed to high levels of two types of air pollution: fine particle pollution from wildfires, and ground ozone.

Ground level ozone is the main component in smog, reaching its highest levels on hot, sunny days.

The study found that between 2001 and 2020, exposure to high levels of combined air pollution rose dramatically in western states – by 25 million “persons a day” each year. This is a measure that takes into account both the number of people affected and the number of days of exposure.

Each type of air pollution alone can have health effects, said researcher Deepti Singh, assistant professor at Washington State University in Vancouver, Washington.

In the short term, it can make breathing more difficult, and exacerbate existing heart conditions or lung conditions such as asthma.

Singh added that research indicates that simultaneous exposure to both types of air pollution may exacerbate the damage.

In 2020, US wildfire activity was “significantly above” average, according to the National Interagency Coordination Center. That was largely because the fires were so big, burning over 10 million acres. It’s part of the trend in recent years toward large wildfires and long fire seasons.

One driver of the increase is climate change, said Christina Dahl, a senior climate scientist with the nonprofit Union of Concerned Scientists. Higher temperatures and droughts mean more dry grass, trees and other plants – and more “fuel” for wildfires.

There are “fire suppression” policies in place that have allowed this natural fuel to grow excessively, Dahl said.

The fires themselves claim lives and destroy property, while plumes of smoke cast a shadow over entire regions. Air pollution from western wildfires can spread thousands of miles, Dahl said, even affecting air quality on the East Coast.

Much of the research on this pollution has focused on particulate matter. What’s special about the new study, Dahl said, is that it looked at people’s common exposure to wildfires and ozone pollution.

This is important because wildfires do not appear in a “vacuum,” noted Dahl, who was not involved in the research.

The results were recently published in the journal science progress, based on air quality data from US and Canadian government monitoring stations for the period from 2001 to 2020. The researchers tracked people’s exposure to days when ground-level particulate matter and ozone pollution were particularly high — in the top 10% of their annual levels.

Over time, researchers found that these double exposures became more common in large areas of the West, specifically during the late summer wildfire season. This trend was largely driven by a shift in the ‘seasonality’ of extreme particle phenomena.

Singh explained that particulate matter in western states has traditionally been at its highest during the colder months – when ozone pollution is naturally lower. But summer wildfires upset that dynamic, causing more “repetitions” of both types of pollution.

Most of the increase has occurred since 2015, coinciding with hot, dry summers and widespread wildfires.

The researchers note that in August 2020, there was a single day in which more than 68% of the western United States experienced severe conditions in both types of pollution – representing about 43 million people.

“We can expect these exposures to continue to increase,” Singh said.

This does not mean that nothing can be done. With climate change being the driver, Dahl said one of the key solutions is to reduce greenhouse gas emissions. They are released when fossil fuels are burned for electricity, heating, and transportation.

Singh and Dal both refer to another method for fighting wildfires: “prescribed burns”. This refers to carefully planned and controlled fires that reduce the density of dry vegetation that fuels wildfires.

Dahl pointed out that these fires can in themselves affect the quality of the air. But, she said, by reducing the chances of major wildfires starting, it may have something to do with whether an ounce of prevention is worth a quintile of treatment.

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