Scorching heat waves and more frequent wildfires are reversing a generation of gains in clean air in the United States, a new study finds.
Peer review research by climate analysis firm First Street Foundation, has predicted that by mid-century, increased levels of microscopic soot particles and ozone molecules entering Americans' lungs will return to levels they were at in 2004 — before a decades-long federal campaign to clean up the air.
Climate change is moving the United States from a model where average days of bad air are “unhealthy for some to days that are unhealthy for all,” co-author Jeremy Porter told The Hill.
Porter said federal regulations led to steady improvements in air quality from 1963 until about 2016 — when the negative impacts of climate change outweighed the positive pressure from clean air enforcement.
“We see the biggest increase in the most dangerous sectors [air] days,” Porter said, while noting that each category of unhealthy air was “decreasing” in frequency.
“We are undoing two decades of progress on air quality,” he added.
These changes have already had subtle but profound effects, according to the study.
For example, declining air quality has increased the number of days children in the western United States cannot play outside safely fivefold since 2000.
And about 14 million U.S. households (about 10%) can expect to experience at least one week of “unhealthy” air quality designated by the Environmental Protection Agency (EPA) each year.
In some hot spots, those numbers are even worse: About 6 million of those homes — located in the West Coast, Midwest and Northeast hot spots — can expect two weeks a year of bad air.
Although these declines in air quality will occur across the country, they will be particularly pronounced on the West Coast, where ozone from baking asphalt combines with toxic particles from wildfires and from the burning of fossil fuels, First Street researchers found.
Over the next thirty years – the average mortgage term – this region will see a notable increase in the number of bad air days, according to the study. Los Angeles, for example, currently experiences 47 days per year when the air is – at minimum – dangerous for children and people with chronic illnesses; By 2054, First Street data projects that Angelenos will face an extra week each year when it is unhealthy for these groups to be outdoors.
In California, “susceptible” groups make up the majority of the population: approximately 28 million people are old, young, or have heart disease or diabetes, or more than 70% of the population.
And California is not alone. First Street researchers found that by 2054, most U.S. cities – New York, Chicago, Los Angeles, Houston, Philadelphia and Jacksonville leading the way – will experience dramatic growth in the number of households in areas where air has been stale for at least a week and a half. per year.
These changes are already happening, driven by two very different contaminants, each linked to climate change: PM2.5 and ozone.
PM2.5 is the official shorthand for particles less than 2.5 microns in diameter, or smaller than about one thirtieth the width of a human hair.
These free-floating particles are small enough to enter the bloodstream and interfere with a wide range of physical systems. But most of them are combustion products, either fossil fuels, agricultural waste, vehicle exhaust or floating smoke from forest fires.
As the incidence of huge and destructive wildfires has increased throughout the 21st century, PM2.5 levels have also increased, according to First Street researchers. wrote last year in Fire magazine.
This study found that a “massive release” of PM2.5 from a wildfire was sufficient to predict the number of unhealthy air days in neighboring municipalities “without significant computational load.”
Nationally, rising PM2.5 levels from wildfires and rising ozone levels from increased heat now expose more than 83 million people – about a quarter of the population – to “unhealthy” air quality, according to First Street.
Of these, around 10 million face “very unhealthy” air quality – and 1.5 million “hazardous”, characterized by the kind of haze that has turned red eyes and bloody noses in the Northeast and the upper Midwest as wildfires grew out of control across Canada in 2017. summer 2023.
In some places, this risk is particularly concentrated. Most West Coast counties are expected to experience three weeks per year of poor air quality days, according to the First Street study. \
It has been found that some hot spots, like the San Francisco metro area, California's Central Valley, and Southern California, can expect 3 months of air that is too unhealthy for sensitive groups (children, seniors or people suffering from diabetes or heart disease) can go out.
This pollution is already costly in human lives. According to a 2021 study in nature, PM2.5 kills about 47,000 Americans per year. By some estimates, improved air quality has saved a quarter of a million American lives since the regulations took effect – improvements that are now eroding.
To worsen the public health situation, while increased heat increases PM2.5 levels by causing an increase in the number of wildfires, it also increases the impact of these increased levels on the people who burn them. breathe. Since the heat and PM2. 5 load the circulatory system, they combine to cause a higher increase in heart attack deaths than either would alone, according to a 2020 study. study find.
PM2.5 impacts are the main cause of air quality decline, but not the only one. According to First Street research Published in Atmospheric Environment:
Unlike its role in the atmosphere, where it blocks cancer-causing ultraviolet rays, ground-level ozone has a more insidious effect. Ozone forms when heat and sunlight cause a reaction between two pollutants characteristic of agricultural pollution and fossil fuels: volatile organic compounds and nitrous oxide.
Once inhaled, ozone bypasses the body's first line of defense against pollution in the nose and mouth and reacts with cells lining the lungs, damaging them and causing them to leak food-dissolving enzymes into the airways, according to an EPA fact sheet. Ozone also causesa sequence of events leading to lung inflammation.
“The statistical signals are clear. We are seeing a rapid increase in air pollutants after decades of legislation aimed at reducing pollution,” Matthew Eby, CEO of First Street, said in a statement.
After decades of improvement, Eby added, “the concern going forward is that climate is much harder to regulate than industry.”
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