Every technology fuel, if not handled properly, has safety issues. I believe that just like cell phones and computers, it's evolved. There are companies such as Roush and others that have put lots of money into making sure that it meets the needs and is safe. We wouldn't put our brand on it if we didn't believe it to be safe. I'm sure that Canada Post wouldn't put their drivers in them if it weren't safe.
Propane is heavier than air. When it's not under pressure, it settles and then evaporates. With respect to the impact on garages, typically, most of the garages are set up to ventilate for gasoline and diesel. They have similar operating properties, so if they're ventilated for gasoline and diesel, they'd be fine for propane. In contrast, for natural gas, typically major modifications have to be made to a garage.
Again, as Cameron mentioned, it's an educational issue, because the technology has evolved, not only on our side but on the dispensers. So it is safe.