Thanks!
The researchers have put together list of the top ten smells which they say are the best predictors of Alzheimer’s. These are; strawberry, smoke, soap, menthol, clove, pineapple, natural gas, lilac, lemon and leather.
I think that would be t-butyl mercaptan, the additive they put it natural gas to make it smell bad. Natural gas has no real odor by itself.