Commercial or large scale hog farming. They keep the hogs inside barns and there must be cooling ventilation as hogs do not have sweat glands. It is why they like to wallow in water or better yet, mud. That many animals inside and electricity shut off in this heat would cause them to overheat and die.

I have one hog and as long as she has a wallowing hole filled with water and plenty to drink and shade from the sun, she is fairly comfortable in the hot days of summer.