heat index

i know the heat index has something to do with the temperature and the humidity, sort of a reverse of the wind chill, but is there an age-adjusted heat index? i remember 100 degree days where it didn't feel like my brain was melting. and cindy thinks it's because i was driving her convertible with the top down! i'm thinking maybe temp plus humidity plus age plus amount of hair* (*or lack of it) and plug it into some formula and it comes out to...HOT.