By the way, my comment about having a second person is a direct reply to the OP's concern about having strong acid, formalin, etc. Obviously, normal darkroom chemicals aren't that risky. I believe Formaldehyde is both a respiratory irritant and flammable in gaseous form. In certain instances, especially when multiple jar of chemicals were knocked over, it won't take much to go from Oh, no! to situation getting out of hand.