The US Government’s Center for Disease Control has officialized the following scientific evidence on the transmission of the coronavirus:

  1. Extremely low risk of transmission from surfaces.
  2. Extremely low risk from taking outdoor activities.
  3. Remarkably high risk of meetings in closed spaces, such as offices, places of religious service, cinemas or theatres.

Other data shows that the viral load required to start the disease is ~ 1000 viral particles (vp).

  1. Breathing: ~ 20 vp / minute.
  2. Speech: ~ 200 vp / minute.
  3. Cough: ~ 200 million vp (in a poorly ventilated environment particles can stay airborne for several hours).
  4. Sneeze: ~ 200 million vp.
  5. Being around someone (~ 2m away): low risk if it is less than 45 minutes.
  6. Talk to someone face to face (with mask): low risk if it is less than 4 minutes.
  7. Someone walking alongside you / running / cycling: low risk.
  8. Well ventilated spaces, with distance: low risk.
  9. Shopping: medium risk (can reduce downward, limit time, and follow hygiene)
  10. Interior spaces: high risk.
  11. Public toilets / common areas: high risk of fomites / surface transfer.
  12. Restaurants: high risk (reduced to medium risk when sitting outdoors with distancing and correctly cleaned surfaces).
  13. Workplaces / schools (even with social distance): extremely high risk, including high risk of transferring fomites.
  14. Parties / Weddings: extremely high risk.
  15. Business / conference networks: extremely high risk.
  16. Arenas / Concerts / Cinemas: extremely high risk.

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