When setting the scene for your players, what a place smells like is often neglected... yet smells in the real world can be very evocative, a single whiff spawning memories (pleasant or otherwise) of past events.
If you find it difficult to come up with much in the way of olfactory description, whether when writing your notes and planning the adventure, or during the course of the game itself, this may well be the resource that you need. Most of us, even if smells are something we have thought about, don't get much further than musty libraries, the odd mothball or whiff of perfume in a lady's chamber and that really vile smell of rotting corpse at the crime scene....
So peruse this list and give your characters' noses something to really twitch at. The hundred examples given also give the strength of the smell, you may wish to vary this, but remember that the strength of a stench can be an important factor so don't just leave it out.
There's a good mix of the pleasant and unpleasant, and some are quite vague... leave it to your players' imaginations, for the mere hint of a whiff will set their wheels turning.
And for the doubters when you roll 95: It smells very strongly like fear - yes, fear does have a smell! It's difficult to quantify, to explain, but once smelled, never forgotten....
An excellent resource for an oft-neglected aspect of description that will help make your alternate reality become more real.