Weakened smelling is common in age. Two studies here show that this phenomenon frequently reveals itself in inability to detect ethyl mercaptan, the warning agent most commonly added to propane (LP-gas). The first study compared 21 young (18-25 years) with 21 old (70-85 years) persons for (a) detection threshold (average ten times higher in the elderly), (b) suprathreshold odor strength (weaker for the elderly did worse). Seven of the 21 elderly failed to detect ethyl mercaptan did above a concentration associated with the boundary between acceptable and unacceptable levels of propane. Three of these failed to detect the odorant at a concentration where accompanying propane could explode. In the second study 50 of 110 persons over 60 years failed to detect odor reliably in commercial odorized propane diluted to the Department of Transportations safety standard (one-fifth the lower explosive limit). Six of 52 persons under 40 also failed. The elderly person would seem at high risk of LP-gas fire.