Waste from thousands of old industrial sites may be released by floods

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As sea levels rise, coastal areas face a growing risk of flooding. But humans and environments near urban centers and the ocean may face issues beyond rising water. These areas have also been home to a large number of manufacturing facilities.

Over the years, many of them may have left toxic chemicals in the soil. And now, those areas are also being threatened by floods. When it rains too hard or the sea rises too much, people nearby can expect to be exposed to a wide variety of leftover material and chemicals, some of which aren’t meant to be ingested or touched by humans.

How big is the risk? Many of our largest cities lie near the sea. By some counts, in 2020, around 400 million people lived within 20 meters of sea level and within 20 kilometers of a coastline.