As a teenager it was my job to gas our facility at the end of summer. Huge warehouse of several large rooms. I would set up a five gallon bucket of sulfuric acid in each room with a planned escape route. Drop a small paper bag of cyanide crystals in each bucket as I passed by. I was so paranoid I'd hold my breath for the entire run until I safely exited the building and locked the last door. I had already posted warning signs at every entrance and had amyl nitrate capsules on hand just in case. my greatest fear was falling down while making my run. Not really a run, more like a fast careful walk that should be less than a minute. I'd do a dry run a couple times as rehearsal before actually dropping the crystals in the acid. After lockup I would go to a window to watch insects just drop out of the air. I learned to really hate the horrible stench of that gas. Next morning it was my job to open the warehouse dock doors and then let it air out for the weekend. Basically you open the dock doors first run away and then come back later to turn on fans at windows when most of the gas is gone. By the next day it was safe enough to bring in the workers. Saying you can't gas a small area to kill a room full of people makes no sense to me. I've worked with this gas and it's horrible.