My office at work smells terrible, old and musty - the building itself is very old with very few windows. I want to freshen it up a bit but I don't like scented candles (plus those are not safe for our work environment) I don't like the plug-ins either, too many chemicals. Is there a safe alternative? Could I use some essentials oils, like orange, lemon or peppermint? If so, what could I do with them since I can't really heat them? Ideas? Thanks in advance.