> A wet-bulb temperature of 95°F (35°C) is the theoretical limit for human survivability for up to six hours of unshaded outdoor exposure
Both the sources you linked say that 35 degrees is the limit in the shade as well.
> It has been thought that a sustained wet-bulb temperature exceeding 35 °C (95 °F)—given the body's requirement to maintain a core temperature of about 37°C—is likely to be fatal even to fit and healthy people, unclothed in the shade next to a fan
Guess technically, since shade is cooler, then if the temperature was X and shade is (X-shade), then if wet bulb was at 95, then you could go into some shade to get cooler. Or, since wet bulb is at 95 is same in sun and shade, then if it is at 95 deg in shade you are in danger, and if you walked into the sun, you'd be in even more danger.
or to try and say another way. Temperature is Temperature, and if in Sun you are probably hotter. But wet bulb 'limit' would be same, and you'd hit the limit faster in the sun.
Both the sources you linked say that 35 degrees is the limit in the shade as well.
> It has been thought that a sustained wet-bulb temperature exceeding 35 °C (95 °F)—given the body's requirement to maintain a core temperature of about 37°C—is likely to be fatal even to fit and healthy people, unclothed in the shade next to a fan