High temps? Think twice about reaching for that fan 

Rising temperature may automatically have us reaching for an electric fan, but a new study suggests that that fan may do us more harm than good. And the reason may lie with the heat index, which is a measure of temperature and humidity. Researchers had a small number of men sit for two hours in either very hot and dry (heat index of 114 F) or very hot and humid conditions (index of 156 F) — some with fans and others without fans. Those who used fans in hot and dry conditions had worse measures of body heat, including cardiovascular strain, whereas those in humid conditions showed an improvement in most measures except for sweating. Public health organizations including the CDC advise against fans for extreme heat, but this study suggests that fans may be OK in certain conditions. However, the study was conducted only in young men, so the findings cannot be generalized to apply to women, children, or the elderly