I used to work in a chemical plant.
One night I cam back to the office in OUR building and mentioned the wonderful smell of fresh-mown grass outside.
The chief instantly went relatively pale and ran to the phone to tell the other building about their leak
(Was it phosgene? I forget. They used one-ton cylinders of phosgene and one guy, before my time, managed to UNSCREW the whole valve assembly when he thought he was tightening it. Luckily he was wearing full protective gear and the wind was away from town that night.)
When dilute, it smelled great. It didn't rip your lungs out until it got thicker. I was just lucky with the wind.
They also used cyanide in that building. "If you see anyone go down on one knee, RUN AWAY!"
