In 1944, a small town in Illinois was gripped with fear that someone was spraying a toxic gas into their homes as they slept. And while there have been several explanations, there isn’t any one that’s recognized or accepted as the truth.
Research:

Robert Moses and the Shaping of New York, Part 2
42:12

Robert Moses and the Shaping of New York, Part 1
41:59

SYMHC Classics: Eradication of Smallpox
43:25