The scope of wildfire smoke is globalizing and undoing progress on clean air | ET REALITY

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On the heels of an exceptionally hot and smoky summer, two new reports released Wednesday confirmed what many Americans have already been seeing and breathing.

Smoke from increasingly frequent and increasingly large fires has begun to undo decades of hard-won improvements in air quality, and the problem is expected to worsen, not only in the United States but around the world.

More than two billion people were exposed to at least one day of fire-related air pollution each year between 2010 and 2019. A report from researchers in Australia found. And in the United States, wildfires have undone about 25 percent of previous progress in cleaning up air pollution in states from coast to coast.

“People know it’s becoming a bigger problem in Western states,” said Marissa Childs, a fellow at Harvard University’s Center for the Environment and co-author of the study. focused on the United States. “But I was very surprised when we did some of these estimates and saw that states all the way to the East Coast were being influenced.”

While her paper does not include data from 2023, Dr. Childs said the wildfires in Canada and subsequent smoke over large swaths of the northern United States this year had shown “more than ever” that everyone will be affected by the rising problem. of wildfires, no matter where they live.

Climate change is one of the driving forces behind worsening fires around the world. As the atmosphere warms, many forests and other natural ecosystems become drier and more likely to catch fire. “It’s very clear that at some point in the last five to 10 years, something has changed,” said Marshall Burke, a professor of environmental policy at Stanford University and co-author of the report that focused on the United States. “There is no need to manipulate the books.”

Together, the two studies show how wildfires are a growing health threat. Wildfire smoke can contain a variety of pollutants, including fine particulate matter or PM 2.5, a type of air pollution made up of very small particles that can invade the lungs and bloodstream.

Thanks to the Clean Air Act, air pollution in the United States has generally improved since the 1970s. But PM 2.5 levels, which the Environmental Protection Agency routinely tracks, had been declining , rose sharply again around 2016.

Since 2016, wildfire smoke has had a statistically significant effect on PM 2.5 trends in 35 of 48 continental states, according to the study by Dr. Burke and Dr. Childs. (The data set did not include Alaska or Hawaii.) The effect was most noticeable on the West Coast, where air quality has worsened dramatically in recent years. But even in some New England states, the smoke caused pollution levels to stabilize after many years of decline.

Although the air is now cleaner in the United States than in many other parts of the world, air pollution remains a public health problem. “It’s pretty clear that wildfire smoke is affecting a lot more people on a lot more days than before,” said Christopher Tessum, a professor of environmental engineering at the University of Illinois Urbana-Champaign who researches air pollution but was not involved. . in any of the studies.

Globally, pollution from fires is taking a heavier toll on residents of poorer countries.

The study led by scientists at Monash University in Australia found that each year between 2010 and 2019, each person around the world had an average of almost 10 days of exposure to bushfire smoke. The researchers found that the concentration of polluted air was significantly higher in poorer countries.

Smoke exposure between 2010 and 2019 was also higher than during the previous decade, underscoring the prevalence and health risks of wildfires.

“We need to put a lot more resources into low-income countries to combat fire smoke,” said Yuming Guo, an environmental expert at Monash and co-author of the study.

The study incorporated data from both wildfires and those planned or controlled by people, such as prescribed burns. The researchers used several sources to collect pollution data and examined ground-level ozone levels in addition to PM 2.5 levels. While ozone high in the atmosphere protects us from harmful radiation, ozone near the ground can cause respiratory problems and aggravate respiratory diseases such as asthma, bronchitis and emphysema.

Countries with hot, dry conditions that make them vulnerable to wildfires were particularly choked by PM 2.5, including those in central Africa, Southeast Asia and South America.

“Different countries experience different fire smoke,” Dr. Guo said. “Therefore, different countries should deploy different resources.”

Determining which approaches to use will be a complicated endeavor anywhere.

“You can’t do it the way we’ve addressed, for example, industrial pollution or automobiles,” said Colleen Reid, a geography professor at the University of Colorado, Boulder, who studies the health impacts of wildfires. , but was not involved in any of the documents released Wednesday. “There’s no scrubber or catalytic converter, some kind of piece of technology that you can put into a wildfire.”

“As we work on policy solutions to try to tackle wildfires, we can also protect people’s health by investing in better indoor air quality,” added Dr Reid, noting that it was important to ensure that people knew how to protect themselves. outside on smoky days wearing masks or respirators. He also highlighted the importance of addressing climate change.

“In addition to all the policies to address wildfire smoke, we obviously need significant changes to lower our greenhouse gas emissions,” he said, “so we can try to address the climate side of the equation that is increasing the risk.” of forest fires”.

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