I'm sorry about your husband. Many things happen coincidentally.
A lot of things are incorrectly labeled by companies and agencies who have no understanding of what the chemical or biological agent actually is or does. I have seen people afraid of WATER because it was referred to as "dihydrogen monoxide" and were told that it was dangerous when exposed to an excessive amount (like you'd drown, duh). So a group of clueless people actually demanded it be banned from schools and public buildings. Caused a stir among the more non-sciencey crowd in our area until we convinced them that getting rid of water would make for a real interesting reassessment of fire codes, hygene, cafeteria operations.
I checked propane out to make sure that my databases were accurate. According to Occupational Safety and Health Administration (OSHA), Material Safety Data Sheets, Chemistry and Physics handbook, Merck Index, and my Toxicology Handbook, propane is not considered a health risk other than flamablilty.
If you are worried about exposure to any specific substance, you can look up the MSDS sheets. Every chemical has to have a MSDS and most businesses, schools, etc. are supposed to keep these on the premises. We were even required to keep them for the white-out, markers, copier toners, you get the drift.