March 1, 2024

Climate change is erasing previous gains in air quality – fires are the main culprit

Air quality in the U.S. is expected to decline in the coming decades, returning to where it was in the mid-2000s as a result of climate change, according to a new report. The report comes with an online tool for users to zoom in on individual properties to see what kind of air quality residents might experience in the future. It paints a picture of a changing landscape for regulators, who will have to adapt to evolving threats.

“Air quality really highlights how climate change is being felt by individuals.”

A hotter planet sets the stage for more wildfire smoke and supercharges the chemical reactions that lead to air pollution. This means the game is changing when it comes to how to prevent pollution in the future. After decades of success in controlling pollution from smokestacks and tailpipes, climate change is undoing some of those gains.

“Air quality really highlights how climate change is being experienced by individuals,” says Jeremy Porter, lead author of the report published by the nonprofit research organization First Street Foundation. “Really serious floods and wildfires are relatively rare, [although] we see them more and more often. But something like poor air quality doesn’t just affect the low-rise homes on the street, it affects everyone in the community,” says Porter. First Street has already launched surveys and online tools to assess flood, fire and heat risks at individual properties.

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The group’s most recent work shows that about 10% of properties in the U.S. (about 14.3 million) already have to deal with a week or more of days when air quality is considered “unhealthy” due to air pollution. fine particles, also called soot. Almost half of these properties are in much worse shape, experiencing two weeks of unhealthy air quality days.

To find out, First Street analyzed data from the Environmental Protection Agency’s air quality sensor network across the country. Porter and his colleagues were able to combine this data with First Street’s existing peer-reviewed fire and heat models to make predictions about the future.

First Street modeled air quality 30 years from now, the length of a typical mortgage. On its current trajectory, air quality in 2054 could return to the level it was in 2004, according to First Street, “destroying 20 years of air quality improvements.” A further 1.7 million properties are expected to experience 10 or more days of poor air quality per year due to soot and air pollution – a 15% increase from today.

This upward trend reflects a “climate penalty,” the report says. Smog, or tropospheric ozone, in technical terms, is produced through a photochemical reaction where nitrogen oxides and volatile organic compounds react with each other in sunlight. As a result, air pollution can worsen on hot, sunny days. Climate change is making heat waves longer and more intense, and pollution is part of that problem.

Hot, arid conditions also prepare the land to burn. Fire is the main factor in air deterioration with climate change, the report concludes. It’s particularly egregious in the western US, where the number of days with poor air quality grew by as much as 477% between 2000 and 2021.

This number is based on the EPA’s color-coded air quality index and counts the number of days in which the index value is at least considered “unhealthy for sensitive groups” – an orange day. Red days are “unhealthy”, purple days are “very unhealthy” and brown days are considered “dangerous”. Averaging the highest daily soot levels in the US, researchers found that the highest average value has increased from orange to red since 2000.

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This often accounts for peak particle pollution levels during specific events, such as wildfires. The health risks from brief, sudden periods of pollution are different from those associated with persistent exposure to pollution resulting from living near a busy highway, for example. Health risks, including problems related to respiratory and cardiovascular diseases, increase with chronic exposure.

“If we have, say, more fires but less pollution the rest of the year, we would see these acute effects increase, but they will be offset by decreases in the chronic effects,” says Drew Shindell, a professor of earth sciences at Duke University who studies climate change. climate change and air quality, but was not involved in the First Street report.

Shindell also highlights that there is still opportunity to change the trajectories outlined in the report. Just as the Clean Air Act led to major improvements in air quality between the 1970s and 1990s, the U.S. has an opportunity to act now. Cleaning up pollution will have to look different than it used to for policymakers, Shindell and Porter say.

“Someone’s job as an air quality regulator is changing because before 100% of your attention would be on emissions from human activities – then you would be concerned with power plants, industry and motor vehicles,” says Shindell. “We did a good job controlling a lot of those things. But we haven’t done a good job of controlling greenhouse gases.”

In other words, to control soot and air pollution, regulators will also have to prioritize reducing other pollutants – the carbon dioxide and methane emissions that cause climate change. They will also have to think about things like forest management to better keep wildfires under control. All of this ties the local effects of air pollution to what’s happening in the world at large, as well as concerns about what your neighbors might be emitting. Last year, wildfires in Canada sent a plume of smoke into the northeastern U.S., causing New York City to briefly hold the title for the worst air quality in the world.

To see historical data and forecasts for future air quality in your area, you can check First Street’s online tool at It uses peer-reviewed models from First Street to predict floods, fires, heat, and now air quality risks. It will show how a property ranks compared to others in the US when it comes to local air quality, what sources of pollution are nearby, and how many days of poor air quality in the area can be expected now and in the future.

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