A couple of decades ago the cause of death would be listed as natural causes and his family would say he had "worked himself to death"
Now they do autopsies and they find out reasons but that does not mean that the reasons were not there before only that they were not recorded.
BTW no one in the US dies from "old age" or "natural causes" any more which is causing the rate of certain conditions to appear to be higher then they were before.
A 25 year old man who died of a heart attack was listed as heart failure, the 70 year old man who died of a heart attack was usually listed as old age. They change they way they report things and suddenly you have a "spike". Because of this it can be very hard to tell what is signal and what is noise.
Since there is no spike in the surrounding area for people who do not work in the fields and since people who work in the fields that are in cooler areas also are not seeing any sort of spike it can be cautiously concluded that this is not caused by any thing more then more exact record keeping.
Quit using logic and being reasonable. It’s clearly time to panic!