I don't believe that is correct. Propane, when it leaks, falls immediately to the ground and hugs it and literally drains down to the lowest area it can find. It would have to find wind and wind currents of a continuous thermal nature that usually peter out when the sun goes down.
I've never understood why, if freon kills ozone and ozone at surface levels is such a dangerous substance that the T.V. weather constantly shows a movie graphic each hot summer night of it blowing from Sacramento up into my neck of the woods... Why wouldn't we want freon leaking from auto airconditioners to kill off this supposedly bad ozone?
So much of this scare tactic is just massive B.S., designed to keep State and Federal pissants in a government job for a big fat cat government pension. The putrid politicians that campaign on these fears are more toxic to taxpayers and taxpaying businesses who are already overburdened by these parasites, than any supposed toxic gas!!!
Besides that, people that continue to swallow this bellicose belching of gaseous baloney are becoming inert in their ability to think for themselves!!!
Please feel free to correct me where I am in error.
This is really an interesting subject, because you see that some substances can be harmful at low altitudes and beneficial at high altitudes. Just for the record, I heard an interesting item on the TV news a few weeks ago: they said new research shows that carbon dioxide may radiate heat AWAY from the earth at high altitudes, while it absorbs heat at lower altitudes (the so-called greenhouse effect.) So the plot thickens, and it's clear that we haven't done nearly enough research to conclude that the greenhouse effect even exists.