It's not just an aging population, it's the big increase in the use of air conditioning. I'm a lifelong Michigander, none of my schools or residences had air conditioning when I was growing up, and I don't have air in my current house (although it's prepped to add it). In less than two weeks, I am sending two kids off to colleges in Michigan, they are bringing box fans because their dorms are not air-conditioned, nor are many of the classroom buildings.

I don't think people have enough experience with air-conditioning units to maintain them properly--I know I don't, having no experience with such. Perhaps air conditioning units need a tighter maintenance schedule than is being followed currently. Lots of places here have so-called "water features" indoors, fountains and waterfalls, I would hope that they keep those properly cleaned, also.

The CDC should look at increasing use of air conditioners, not just go to the easy "aging population" excuse. I'm going to guess that the CDC headquarters buildings just might be air-conditioned, and might employ workers that have grown up with all their buildings having been air-conditioned.