Source: Calculations from NOAA temperature data for Reagan National Airport, COVID-19 case counts from the Virginia Department of Health.
This post take the place of my normal posting on trends in new COVID-19 cases in Virginia. It really an opportunity to gather together a few bits of information about heat, humidity, and transmission rates of COVID-19.
The quick upshot is that the environment that maximizes your risk of transmission of COVID-19 is cold, dry, stagnant air. In short, for avoiding COVID-19, the warmer, the wetter, and the windier the better.
But what about using heaters to extend the outdoor dining season? Electric heaters will reduce the relative humidity of the air. Doesn’t that raise the risk of COVID-19 transmission.
My answer is no. I’m almost sure that extending the outdoor dining season with heaters provides a net benefit in suppressing spread of COVID-19. The “almost” there isn’t due to the behavior of the virus, but to the behavior of diners.
Details follow. If your sole interest is in outdoor restaurant dining, skip to the end.