JENJAROM, Malaysia Pua Lay Peng first smelled trouble early last year. An acrid odor began waking her up in the middle of the night, and the sky often appeared unusually hazy.

Her neighbors in the quiet, agricultural town of Jenjarom began complaining of headaches, respiratory problems, skin allergies and other ailments. Children were falling sick more often than usual, and one local teacher said she was finding it hard to concentrate at school because of how disturbed her sleep had become.

Pua began feeling lethargic all the time, too, and it was starting to worry her. She also noticed fewer butterflies and insects on her walks around town.

The 46-year-old initially thought the problem was linked to haze wafting in from Indonesia, where agricultural fires are known to rage and cause thick smog in neighboring countries. But that kind of haze shouldnt have been making locals sick, she said.

You could tell that it was toxic, Pua recalled of the smell, speaking from a restaurant in Jenjarom last month.

A chemist by trade, Pua said the foul odor was familiar to her. It smelled like burning plastic.

But who in Jenjarom, a close-knit town of 30,000 known for its farms and palm oil plantations, could be setting fire to so much plastic all of a sudden? Pua was determined to find out.

Together with a small band of other concerned neighbors, Pua embarked on a monthslong crusade to uncover the truth behind the toxic-smelling air. Along the way, they endured ridicule from local authorities and even death threats from mysterious sources. Their investigation helped expose an ugly side effect of a global recycling industry that activists and politicians in Malaysia have described as broken, inequitable and unjust, and that puts the health of ecosystems and local people at risk.