When did indoor air become cold and clean? Air conditioning is one of those inventions that have become so ubiquitous, that many in the developed world don’t even realize that less than a century ago, it didn’t exist. Indeed, it wasn’t so long ago that the air inside our buildings and the air outside of them were one and the same, with occupants powerless against their environment. Eric Dean Wilson, in his just published book, “After Cooling: On Freon, Global Warming, and the Terrible Cost of Comfort,” dives deep into the history of this field. It took more than just...