A n environmental stressor could be;
the weather, too hot, say a heatwave, which can cause heat stroke, dehydration etc, or too cold, where vulnerable people may freeze to death, or develop frost bite etc.
So, some characteristic part of where we live which may, under certain conditions cause difficulty for us or some other living being.
Answer i dont really know thats a very good question
It informs society how it can end up being deadly and society reacted to that by having safe sex and being aware of who they are sleeping with