Air conditioning is one of the greatest inventions of the 20th Century. It?s also killing the 21st ? TechCrunch

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 outsi?