Check out the DVD, “Exodus Decoded”, which I borrowed from my local library. These kinds of naturally occurring poison gas eruptions do happen, even today, and they are very selective. People on higher ground aren’t harmed. One boy in an African village experienced it; everybody living downwind died in their sleep, people and animals alike. The Egyptians allowed the first born son to sleep in a low bed, but the rest of the family would sleep on the roof and were therefore spared. Why it didn’t happen to Jewish families I can’t explain, except that it can be very local as I said.
Why a newly-minted FReeper would resurrect a years-old thread, & replies to me six years later is a mystery. How a newly-minted FReeper would pick this thread out of the ether to start posting on is telling.