How is it that six months into a respiratory pandemic, we are still doing so little to mitigate airborne transmission?

I recently took a drive-through COVID-19 test at the University of North Carolina. Everything was well organized and efficient: I was swabbed for 15 uncomfortable seconds and sent home with two pages of instructions on what to do if I were to test positive, and what precautions people living with or tending to COVID-19 patients should take. The instructions included many detailed sections devoted to preventing transmission via surfaces, and also went into great detail about laundry, disinfectants, and the exact proportions of bleach solutions I should use to wipe surfaces, and how.

My otherwise detailed instructions, however, included only a single sentence on “good ventilation”—a sentence with the potential to do some people more harm than good. I was advised to have “good air flow, such as from an air conditioner or an opened window, weather permitting.” But in certain cases, air-conditioning isn’t helpful. Jose-Luiz Jimenez, an air-quality professor at the University of Colorado, told me that some air conditioners can increase the chances of spreading infection in a household. Besides, “weather permitting” made it all seem insignificant, like an afterthought.