Exit Acid Rain, Enter Microplastics And PFAS. Unlike Acid Rain, They're Impossible To Get Rid Of.
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Beginning around 1990, the US and Europe passed legislation that limited the amount of acid-forming pollutants — such as sulfur dioxide and nitrogen oxides — that power plants could emit. Laws requiring car manufacturers to put catalytic converters into new vehicles, which reduced harmful emissions, were also taking effect. That brings us to today: While precipitation in some regions is still unnaturally acidic, on the whole, acid rain is largely a problem of the past and a major environmental success story. Now, however, there’s another problem with our rain — and it’s even more alarming. While precipitation has become less acidic, a growing body of evidence suggests that it’s now full of many other pollutants that pose a risk to public health, including microplastics. And unlike the compounds that cause acid rain, these pollutants are almost impossible to get rid of.
As government regulators focused on reigning in air pollution, companies were busy generating new sources of pollution, including plastics and PFAS, the so-called forever chemicals. PFAS, which stands for perfluoroalkyl and polyfluoroalkyl substances, are a large group of compounds used, among other things, to make fabric stain-resistant and pans nonstick. Over time, these modern-era substances — which famously take decades to millennia to degrade — have leached into the environment, reaching every corner of the planet, no matter how tall or deep. Microplastics, PFAS, and some other compounds, such as pesticides, are now so widespread that they’ve essentially become part of our biome, not unlike bacteria or fungi.
A number of studies, for example, have documented microplastics in rain falling all over the world — even in remote, unpopulated regions. For one 2020 analysis in the journal Science, researchers documented microplastics in rainwater that fell on several national parks and wilderness areas in the Western US. Most of the plastic bits were microfibers, such as those shed from polyester sweaters or carpeting on the floor of a car. The researchers estimated that more than 1,000 metric tons of plastic from the atmosphere fall on parks in the West each year, including both as rainfall and as dry dust. That’s equivalent to roughly 120 to 300 million plastic water bottles, according to the study.
The largest source of those microplastics was highways, said Janice Brahney, a biogeochemist at Utah State University who led the Science study. Roads are often littered with plastic waste that gets broken down by cars and kicked up into the air. Those particles are typically lighter than soil, so once they become airborne, they can easily move around in the atmosphere and get grabbed by rain as it falls.
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https://www.vox.com/climate/401600/pfas-microplastics-pollution-rain