米国環境保護庁(EPA)のガイドブックが根拠だと書いてあるから読んでみたらこの部分か
>portable electric fans are not the simple cooling solution they appear to be. Because of the limits of conduction and convection,
>using a portable electric fan alone when heat index temperatures exceed 99°f actually increases the heat stress the body must
>respond to by blowing air that is warmer than the ideal body temperature over the skin surface
> (American Medical Association Council on Scientific Affairs, 1997; CDC, 2004c).
>In these conditions, portable electric fans provide a cooling effect by evaporating sweat. The increased circulation of hot air
>and increased sweat evaporation can, however, speed the onset of heat-attributable conditions (e.g., heat exhaustion).
記事は35℃以上で使うなと言い換えているが原文だとヒートインデックス値で99°Fを超えたらNGとしている
https://en.wikipedia.org/wiki/Heat_index 湿度80%なら気温30℃以上、湿度70%でも気温31℃以上でアウトになってしまうわけで
日本の夏だとハンディファンはほとんど意味ないってこったな
