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There could be about a million 'orphan' oil and gas wells across the U.S. As they age, they can leak greenhouse gases or unhealthy chemicals.
(Image credit: September Dawn Bottoms for NPR)

There could be about a million 'orphan' oil and gas wells across the U.S. As they age, they can leak greenhouse gases or unhealthy chemicals.
(Image credit: September Dawn Bottoms for NPR)