You must take into acount the effect on staff who may be in the space all
day - rather than visitors passing the pleasant (or unpleasant - eg. the
Viking latrine at Jorvik, York, UK) smell just for a matter of seconds or
at most a few minutes.

At the Bosworth Battlefield Centre in Leicestershire,England,
(Shakespeare's Richard III etc.) we did an "evocative" late medieval house
setting, complete with artifical wood-smoke etc. but quickly had to cut
the smells back very drastically because they were making the security
staff and those working in the nearby museum shop feel nauseous.

Patrick Boylan