For context, Australia, where I live, currently sits at ~130 confirmed cases, which makes me feel relatively safe for now, but naturally this will get worse with time as other countries' examples suggest. I will be working from home, avoiding public transport and limiting shopping to the minimum. I live in suburban Sydney, so one of the major population centers.

How safe is it to continue solo outdoors training with the current and predicted COVID-19 situation? Specifically, I mean cycling without a group (i.e. maintaining a good degree of separation from any other humans at any given time). I imagine it has to be considerably safer than e.g. grocery shopping. Can the virus remain airborne outdoors for long periods of time?

  • The risk to have an accident on the road is greater than to get infected by this virus, even it can be spread by aerosols and can exist some hours outside a virus host. On the contrary: sportiv activity will strengthen your immunity system when you practice it alone and not in a crowd of people. Mar 13 '20 at 5:40
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    You may want to adapt your excercise to avoid excercise-induced immunodepression, though: see e.g. ncbi.nlm.nih.gov/pmc/articles/PMC3475230 as a (rather random) starting point. Mar 13 '20 at 21:47

The long and short of it is that the novel coronavirus can be experimentally aerosolized where it can persist in the air for several hours but a number of studies have failed to detect virus in samples taken from the air of the rooms of patients with active disease. But virus has been detected in aerosols near bathrooms surfaces indicates that it is spread over a long distance with mechanical assistance (flushing?). SARS was also spread by one patient with diarhoea with malfunctioning sewer systems aerolized the virus across multiple floors of a building.

Both the Covid-19 and the SARS viruses had an aerosol half-life of 2.7 hours, meaning half the particles drop out of the air after that amount of time, and half of what remains drop out after another 2.7 hours. After a day, roughly nine half-lives, 0.002 (0.2 of 1%) of the original particles remain. As a result, the scientists said, “aerosol … transmission of [the new coronavirus] is plausible, as the virus can remain viable in aerosols for multiple hours.”

The usual spread may be via contaminated surfaces (probably on the cruise ships) and respiratory transmission less so since the rate of symptomatic infection among a patient’s household members was 10.5%

Since you're outside based on the above, the viral load would be miniscule.


https://www.medrxiv.org/content/10.1101/2020.03.09.20033217v2.full.pdf (not peer reviewed yet )

  • Based on that, it would stand to reason that the risk is virtually nil in non-crowded open air areas, as wind would diffuse any aerosol concentrations in a very short time anyways, wouldn't it? Thank you for your answer. I think I'll continue my cycling habits for the time being, but will cut back to indoor training when the situation gets worse, to avoid adding workload to hospitals in case of an injury.
    – user622505
    Mar 18 '20 at 21:00
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    Yes, safe outside and 2m away from anyone coughing in your direction Mar 18 '20 at 21:10
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    Agreeing with the general suggestion of outdoor activity being safe, and having similar concerns, I have noticed how actually you might inhale some of the air "associated" with people you pass; I have noticed "perfume scent" of some of them even from 2m away; so -- be reasonable; don't closely follow "heavy exhalers"...
    – P Marecki
    Mar 18 '20 at 21:57
  • The nose is very sensitive .. presumably at a molecular level. Not the same as respiratory droplet sizes. Mar 18 '20 at 21:59

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