There are two conflicting things I have heard. One more anecdotal:
Wasps can smell when you are afraid of them
The other from reading popular science magacines:
Humans don't produce any pheromones
As far as I know, a pheromone is a smell produced to communicate with members of your own, but also other species. From my understanding these two statements are mutually exclusive.
So: Can wasps smell if a human is afraid?
Any answer with sources is appreciated.