http://askakorean.blogspot.co.uk/2009/01/fan-death-is-real.h...
Quoting from that:
This pamphlet from the EPA[0], at pages 49
and 51, clearly states the hazard of using
portable electric fans during high heat. It
specifically says “Portable electric fans
can … increase the circulation of hot air,
which increases thermal stress and health
risks[,]” and “DON’T use a portable electric
fan in a closed room without windows or doors
open to the outside.”
Problem is, that link now goes somewhere else, and not to a pamphlet at all. Tricky.However, this has been discussed at length here:
https://news.ycombinator.com/item?id=8740683
It's also been submitted lots of times, although the last time was a month ago, so maybe we should see it again:
https://news.ycombinator.com/item?id=11844310
https://news.ycombinator.com/item?id=9825096
https://news.ycombinator.com/item?id=8136969
https://news.ycombinator.com/item?id=5357829
https://news.ycombinator.com/item?id=3943075
https://news.ycombinator.com/item?id=3890949
https://news.ycombinator.com/item?id=3425519
https://news.ycombinator.com/item?id=3310449