Vehicle dealers are pushing back on rules that would increase the number of electric trucks sold in New Jersey. It could be a preview of a brewing fight over state rules about cars.

(Image credit: Spencer Platt)

A few years ago, scientists cracked a murder mystery -- they figured out what's been killing Coho salmon in urban streams in the Pacific Northwest. The culprit: particles from tires.

For decades, Coho salmon were turning up dead in urban streams the Pacific Northwest. The salmon would stop swimming straight, and then die before they had a chance to spawn. Researchers worried that unless they figured out the cause, the species would eventually go extinct. Enter a formidable crew of biologists, modelers, community scientists, environmental chemists. After eventually ruling out the obvious suspects — things like temperature, oxygen levels and known toxins — researchers eventually zeroed in on a prime suspect: chemicals in tires. But the question remained: Which one?

If you liked this episode, check out our other episodes on satellites monitoring emissions and how air pollution could create superbugs.

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(Image credit: Arctic-Images)