Hello there, I came across an interestsing journal article recently that may help people using salamol inhalers.
"Quality improvement project assessing the feasibility of using canister weight to estimate remaining doses in a salamol pressurised metred - dose inhaler" - Beckett RS
A study of families in England found that many were using expired salamol inhalers breathing in just propellant or discarding still working inhalers.
Ultimately it recomended that people are encouraged to weigh their cannister on a kitchen scale and consider that a salamol cannister <10 grams weight suggested close to empty and recommended replacement.
The other interesting part of the study revealed that as the cannister is used up the rate of weight reduction is much more gradual towards the end (I guess because it is mainly propellant leftover) and could be quite misleading for people estimating that they have more medicine than is actually in the inhaler.
I checked some spare inhaler cannisters I had around the house and was shocked when I weighed them they were below 10 grams and would have no medicinal value.
Hope this helps and gets people thinking as I think there is a real danger of getting ill and when you are sick you are not particularly sharp or focused on measurement and might be just inhaling propellant!
Take good care.