Which means what, in this example, exactly? A person in a 60 degree pool is losing more internal body heat than a person simply standing outside in 60 degree weather? Is it still so, if it's a 70 degree pool vs 40 degree weather, or 24 hours at room temp vs one hour in a pool?
Just a disclaimer, I’m not an expert in this area.
Yes, a person in 60° water is losing heat energy more quickly than someone in 60° air. This is because water is much more efficient at transferring this energy - something like 24x IIRC.
Determining an equivalent air temperature requires knowing a bunch of additional factors (e.g. humidity). I don’t know of a rule of thumb you could apply other than saying the equivalent air temperature of water below one’s body temperature would be much colder, and the inverse would be true for water temperatures above one’s body temperature.