Bruce,
How many pidgeons died near the outlet from your fumehood? Or is the outlet scrubbed?
I once worked with big cylinders of anhydrous HF. Didn't really worry me at the time, but looking back the failure of a valve would have been catastrophic. There was an incident when about a litre was spilt onto the floor. Fortunately everbody was in air-fed acid suits. The windows in the lab all had to be replaced!
It's not called "windy Wellington " without good reason - a vigorous breeze was blowing. Not scrubbed, but no residential building for 100 metres or more , and adjacent gardens/lawn showed no ill effects.
I also worked with HF, and always concerned, fortunately only spills were in fume hoods.
One of my bigger concerns as an industrial chemist was when an electroplating tank "lost" 1800 litres of 150 g/L cyanide overnight down the trade waste drain - when most drain waste was acid metal pickling solutions. Lots of dilute caustic immediately dumped, don't think anything died, management was mainly concerned about the cost of the lost dissolved zinc....
Local authority was always repaired their monitoring pH meter, because it would swing wildly, producing "unbelievable data". They were truly the bad old days for the environment....
Bruce Hamilton