Ranking Sports for Coronavirus Risk… the Rock-Paper-Scissors of COVID-19

Highest Risk

I’ve been hearing lots of sports commentators struggling with the relative risks of sports play for catching the virus. So here’s a pictorial explanation of the risks, based on what I’ve learned from all of my reading, primarily from science professor Erin Bromage’s article called “Know the Risks…”

To understand covid transmission, the important thing learn is that according to Bromage you don’t get infected by inhaling merely a single particle of virus; it takes a certain minimum quantity called a minimum infectious dose. I recently heard a football guy call into a sports talk show and refer to getting a ‘viral load.’ This is the same concept… you need to get a few hundred or a few thousand particles to overwhelm your natural defenses. Unfortunately no one knows the exact amount. But they do have a lot of similar information from prior pandemics. So, we start by understanding the interplay of three factors: proximity, duration, and air turnover or ‘dilution.’

Any of these factors can outweigh all the others based on degree. For instance, you can reduce your risk to zero if you’re far enough away from someone… even if the duration is very long and the air flow is low. And if you’re right in each other’s face, no amount of ventilation will help… and duration can be immaterial.

Outdoors and for just a minute or two might not be risky.

Sitting in a crowd for 3 hours might be the toughest of all calls. We can only know if we follow people three weeks after such events.

With the windows closed and being near a driver who is exposed to hundreds of customers, for more than a 5-minute ride, this can be more dangerous than many sports.

A wide open car window should reduce risk tremendously. A public driver does logically reduce the risk by wearing a mask, but forceful air ventilation might make it meaningless. I believe that the wearing of gloves by a taxi driver, while polite, is pointless and contributes to demonstrating a failed understanding of the problem. How do gloves worn by a driver have any impact? By not transmitting germs to the seats or door handles? No; they don’t accomplish that.

Finally, elevators are another difficult one. My source, Dr. Bromage speculates, based on some office building studies that duration is low enough to reduce risk. But it would seem logical that you could make an elevator dangerous with too many people and any highly infective people being present.