sorry man but this is a truly terrible thread. there are loads of things i dont want to be exposed to. i have been exposed to H2S, Br2, Cl2, SO2, HCl(g), (CH3CH2)2O, Cl2O and NH3(g) among others and i will say that they are really unpleasant, some more so than others. these are by no means even close to as lethal (concentration-wise) as many other chems, namely v and g agents, such as tabun, sarin and vx as well as the novichok agents. plutonium also is incredibly dangerous in multiple ways. i believe that speaking in terms of fatal doses by number of molecules, botulinum toxin a is the most "dangerous"