If you were in the N.Y. subway somewhere around 1966, you may have been a guinea pig 🐷
From a 1980 Washington Post article:
“In these trials, one of the Army’s observers reported, small quantities of “a harmless simulant agent,” known as “bacillus subtilis var. niger” were inserted through the sidewalk gratings, producing “aerosol clouds” that “were momentarily visible in the station” below. “When the cloud engulfed people.” the observer continued, “they brushed their clothing, looked up at the grating and walked on.” The whoosh of the trains carried the stuff uptown and downtown within a few minutes, the report said. Even more effective, the Army found, was dumping bigger doees in subway tunnels, where light bulbs containing the bacillus were tossed from moving trains.”
