The odour is probably a volatile bi-product of the curing process and given time will fade. If it is really objectionable and ventilation to outside is not an option what might help is to place as large is practical cloth or porous paper bag of activated charcoal on the shelf and close the door if there is one. Activated charcoal absorbs most organic vapours.
It may be an old wives tale that a cut onion will absorb smells, but I have seen Big Painting contractors putting halved onions in offices to remove the smell of paint and it does seem to work.
