Angelo Gladding
Even heat-adapted people cannot carry out normal outdoor activities past a wet-bulb temperature of 32 °C (90 °F), equivalent to a heat index of 55 °C (131 °F). A reading of 35 °C (95 °F) – equivalent to a heat index of 71 °C (160 °F) – is considered the theoretical human survivability limit for up to six hours of exposure.
— en.wikipedia.org/wiki/Wet-bulb_temperature
Wet bulb for 110 °F and 60% relative humidity is 95.87571793676659.
\[
\scriptsize \begin{align*}
T_\mathrm w = T\arctan(0.151977\sqrt{RH + 8.313659})
\\ + 0.00391838\sqrt{RH^3}\arctan(0.023101RH)
\\ - \arctan(RH - 1.676331)
\\ + \arctan(T + RH)
\\ - 4.686035
\end{align*}
\]