No need to feel bad, it's just good to realize that everything has it's darker side (except for photons I suppose XD).
There are several gases. Some are quite toxic, some are corrosive, and some are highly flammable or pyrophoric.
HBr (not really THAT bad compared to the others)
SiD4 ( Deuterated SiH4)
These are all ones that I have experience with ( other than the couple that I can't list due to legal reasons) but there are other nasty chemicals that are used in the manufacturing process for various electronics.
Anybody who has spent time in a semicon fab also knows that there is a lot of nastiness that is involved in the industry. It's a very interesting industry but, as is the case in many industries, there are definitely risks involved.