I don't know how to help with the cigarettes except to move away when you see one coming your way. I might have a suggestion for the noise, however. There is a device (you'd have to do a bit of research here as I don't know what it is called, but I heard about them from the audiologist) that allows you to wear earplugs and then projects the teacher's voice right to your ear while minimizing the other noise around you a great deal. It might be able to help you.
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Diagnosed with classic Autism
AQ score= 48
PDD assessment score= 170 (severe PDD)
EQ=8 SQ=93 (Extreme Systemizer)
Alexithymia Quiz=164/185 (high)