Last semester we did a lab separating the components of a mixture. Part of the experiment involved subliming NH4CL (ammonium chloride) in an evaporating dish but instead of placing the dish in the hood (as outlined in the lab procedure), our class had to use open air bunsen burners. There were about 6 lab stations doing this all at once, so it got kind of smokey. Each lab station had about .8 grams of NH4CL that sublimed. (.8g x 6 labs = 4.8g total in the air) NH4CL has a lethal dose (LD50 30mg/kg) Which I think means 50% of rats died when given 30mg/kg. So per 1 kg of rat that was given (injected) 30mg, half died, right? So if the average person weighs about 140kg then the LD would be about 2.1g a person right? (30mg/kg*70kg=2100mg=2.1g) Since there were 12 people in the room (typical sized lab room) with no real ventilation, were we in any danger from breathing the ammonium chloride smoke? I asked the lab instructor if we were in any danger before the lab and he said no, there was probably more NH4CL in your last dinner than would be breathed in.