Just for clarity sake -- methyl mercury is completely different from mercury (metal) vapor. Methyl mercury is an organic mercury compound that absorbs through the skin and is lethal in amazingly tiny quantities, causing severe brain and nerve damage even in much tinier traces. Mercury vapor is just evaporated mercury metal -- hazardous, but not much if any more so than many household chemicals (as suggested above), and some of the cleaners some of us might use routinely in reconditioning antique photographic equipment. Given the vapor pressure of mercury after it cools to room temperature, you're in much more danger from inhaling gasoline fumes on the freeway than from inhaling mercury from a Daguerreotype darkroom next door; the only person taking any significant risk is the actual worker, and with modern technology for controlling the vapor, this risk is probably no more than woodworkers encounter from the combinations of chemicals they use routinely (and lots of woodworkers live long, healthy lives -- as, come to that, did many Daguerreotypists even when no particular care was taken with the mercury).