21 mars 2018 · feeling lightheaded flu-like symptoms headaches irritation to the eyes and throat mood changes, including depression nausea. 24 mars 2021 · Smell Natural gas and propane are odorless, so you wouldn’t be able to smell them leaking if it were not for the unpleasantly smelling chemical added to them. If you detect a rotten egg or sulphur smell, it could be a gas leak.