"The smell of peanut/nuts does not come from the peanut protein, so reactions should not occur just because you smell peanut. Allergic reactions to peanut occur mostly when the peanut enters the body, either by licking it, tasting it or eating it.
The smell of peanut should cause no allergic reactions at all, but may make a peanut allergic person feel very uncomfortable because he or she is smelling something that is distasteful and potentially dangerous if eaten. It is likely a defense mechanism to warn the peanut-allergic person to move away from the area, in case they do get into contact with the peanut accidentally."
From that very same page (allergicliving.com/experts/can-i-react-to-the-smell-of-peanutnuts/) a bit further down...
The only exception to the above is if peanut protein itself is in the air that you breathe. If a peanut allergic person breathes enough of the peanut protein in the air, the person can have a serious allergic reaction, asthma attack or anaphylaxis.
Situations in which this are unusual but can happen. For instance, if a large number of people are opening packages of peanut at the same time – e.g. when peanut packages served on an airplane – and the peanut protein dust gets into the air in an enclosed space.