I’m old, fat, and have a tough time handling respiratory infections. I haven’t had COVID so far, and I really don’t want to catch it.
Prevalence of COVID-19 is now about 10 times higher than the first time my wife and I returned to the gym (Post #1163). But (arguably) lower than when we returned to the gym a second time (Post #1421). At some level, the risk of going to the gym or not cuts both ways. It’s a question of what else is going to kill me if I don’t manage to get my heart rate up on a regular basis. So back to the gym it is.
The bottom line is that I’m going to wear a mask. No matter how unfashionable that has become.
Not because I’m stubborn, but because I bothered to calculate the odds. And the decision to go back to the gym, three times a week, will almost certainly expose me to an individual with an active COVID infection, over the course of the year. Not to mention flu. Exposure isn’t infection, but still, this is likely going to be the riskiest thing I do in the near term.
The calculation in brief.
Assuming:
- 11 new cases per 100K per day, officially diagnosed, the current rate in my area.
- A multiplier of 9, to account for:
- An average of three days spreading disease, per infected person
- An average of three total cases for every one officially diagnosed.
- Typically, 25 people in the gym at the same time I am.
- Three-a-week sessions, or roughly 150 gym sessions per year.
Odds that somebody in a crowd of 25 is infectious: 2.4%
That’s calculated as:
- Odds that one person is infectious = (11/100,000)*9 = 0.001
- Odds that any one person is NOT infectious = (1 – 0.001) = 0.999
- Odds that all 25 people are NOT infectious = 0.999^25 = 0.976
- Odds that at least one person in 25 IS infectious = (1 – .976) = 0.024 = 2.4%
Odds of being exposed to COVID in a year of gym-going: 71%
That’s calculated as:
- Odds that nobody is infectious in any one session = 0.976
- Odds that nobody is infectious in 150 sessions = 0.976^50 = 0.29 = 29%
- Odds that somebody will be infectious in at least one session = (1-29%) = 71%
Sure, exposure to an infected person isn’t the same as infection. But gyms are an inherently high-risk place to be. On balance, given that I now own a more-than-lifetime supply of masks, I believe I’ll wear one at the gym. For the time being.
A bit of background.
Just to refresh the facts, without citation as to source.
COVID-19 is spread via aerosols, that is, little tiny droplets of spit that can float a considerable distance through the air.
Any activity that has you talking loudly or breathing hard vastly increases the amount of aerosols produced. Recall that one of the original U.S. tragedies from COVID was a church choir rehearsal where virtually the entire choir was sickened and several members died from COVID. Most countries had at least one similar episode, which is why all the mainstream churches banned singing during the peak of the pandemic.
Gyms are a known high-risk area, for exactly this reason. How do we know? Studies asked newly-infected individuals what activities they had undertaken during the past week, and gyms showed up right alongside indoor dining.
A high-quality mask, such as an N95 respirator, greatly reduces the number of aerosol droplets that you inhale, for a given concentration in air that you are breathing. An N95 is not just better than a cloth mask, it’s vastly better.
Suit yourself.
Source: 3M
Given that masks are no longer required, I’m going back to my pre-pandemic favorite, the vented 3M N95 respirator. These got an irrationally bad rap during the pandemic, because they don’t filter as well on the exhale as they do on the inhale. Still, they filter better than (e.g.) a bandana, or most cloth masks, functioning at roughly the N50 level on the exhale.
From long and dusty experience using these around the house, I find these to be the most comfortable N95 respirators around. I figure, if masks are voluntary, and nobody is wearing them, and individuals are doing a higher-risk activity such as going to the gym, I don’t think anybody will have the right, logically, to object to which particular mask I use.
So I might as well suit myself.
