At Israeli hafganos, sometimes the police use a horrible smelling liquid to disperse the crowd. It smells absolutely putrid! The smell remains in the area for a long time. I was wondering if one is allowed to say a beracha or talk in learning in the vicinity of the smell? Does it make a difference if the smell is artificially created (with chemicals)? What if someone lives near the hafgana and his entire house has the bad smell for two hours afterwards?
The halacha will depend in the ingredients of the spray. If it contains only chemicals, and I assume that they are made out of only chemicals, (if they would be made out of anything decaying, it would be full of bacteria and very dangerous) then you would be allowed to say brachos and learn there. Although it smells terrible, we are allowed to daven and say berachos near such a smell. The reason is because it is only near something that smells because of decay that we have to distance ourselves, and this smell is one of chemicals, and not from decay. If the smell however disturbs you concentration, then you should daven somewhere else.