Time, Distance, and Shielding: Its Not Just for Radiation Workers Any More

I worked for sixteen years in a so-called nuclear facility. So-called because we worked with radioactive nuclear material in sufficient quantities to require us to undergo serious levels of training and use the well-understood Holy Trinity of time, distance, and shielding to protect ourselves from harmful levels of exposure. That thinking applies easily to COVID-19.

Time matters. In radioactivity, unstable elements decay at a constant rate, i.e., the half life; at least for isotopes having half lives in months to millenia, the longer you are near a radioactive source, the more radiation you are going to absorb in a roughly linear time frame, all other things being equal. Think of it like lying out in the sun and eventually absorbing a sunburn. In the case of a virus, the source may be intermittent such as by virtue of a cough, sneeze, or wheeze, but the longer one is near a source, the more chances of being in the range of that sneeze.

Distance matters. Radiation falls off as distance squared (for most geometries) so getting twice as far from a point source such as a test tube decreases your rate of exposure by a factor of four. In the case of a virus emanating from an infected person, I don't know if distance squared strictly applies, but distance matters as the sneeze or cough will be diluted by the greater air volume (distance squared) and eventually fall to the ground if not wafted by winds. Six feet seems to be a rule of thumb for standing around in a checkout line. I would stay much farther than this from other bicyclists or runners rather than be drafting them and pick up their potentially lethal cooties. Especially in this time of rampant allergies. I rode through a countryside of pinon pine and juniper today and my nose did not like it. Fortunately as you can see below, no one was around to complain.

Plenty of distance out here

Shielding in a nuclear facility can be anything from a pair of gloves to stop easily stopped particles and bodily contamination to lead or hydrogenous barriers to diminish gamma radiation or neutrons. Shielding from COVID means masks and gloves. A simple mask may catch most of one's own sneeze. A HEPA or N95 mask will protect from other people's particles but these are in short supply and should be reserved for first responders. Kitchen gloves can work and if you can find or make a simple mask, that is important.

So time, distance, and shielding are your friends. Keep your exposure time to a minimum if people other than you and your loved ones are around. Go get your fresh air where there are few people around. If you have to interact, use a mask. If you have to use an urban trail, avoid peak hours of its use. Above all, ride prudently. This is not the time for a visit to the ER due to a careless endo, "hold my beer" stunt, besting your buddy's Strava on a descent, or texting while riding. Keep your situational awareness radar on 10/10.

I took an 18 mile ride west and north of town today. Passed nine walkers. Seven were on the other side facing traffic and two way off on a dirt shoulder. Passed seven cyclists headed in the oncoming direction on the other side of the street and had one turn from a side street about fifty yards ahead of me. He was a little slower than I, so I stopped to take the picture below, by which time he was long gone. That's less than one interaction per mile and all at distance.

We will muddle through this but the more people think about what they are doing, the less damage will be done.

That is a bicyclist way out in front of me. I kept him there. 
The two walker are on the opposite side of the street.