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Here are some examples of the longevity of SARS-CoV-2 in relation to the dental office:

• The virus is viable up to 72 hours after application to plastic and stainless steel surfaces, like the dental chair.
• The virus is viable up to 24 hours on cardboard surfaces, like glove and mask boxes which are commonly kept in the operatory.
• The virus is viable in suspended aerosols up to three hours, like the bioaerosols created during dental procedures.

“In a study investigating cough aerosols, The Edmonton group demonstrated that cough aerosols are composed of droplets ranging from 0.1 to 900 microns size, of which 97 per cent were less than 1 micron in size, and 99 per cent less than 10 microns.“

• By respiratory droplets and by fomite. Virus found in respiratory secretions and saliva.
• Viral shedding by asymptomatic people may represent 25–50% of total infections.
  • Viral shedding may antedate symptoms by 1–2 days.
  • Viral titers are highest in the earliest phases of infection.

The total allowable particle concentration - building materials, combustion products, mineral fibers and synthetic fibers (particles less than 10 microns) - specified by EPA (U.S. Environmental Protection Agency)

• 50 microns/m³ (0.000022 grain/ft³) - allowable exposure per day over the course of 1 year
• 150 microns/m³ (0.000022 grain/ft³) - allowable exposure over 24 hours

“The complete calculation of this is hampered by our non-understanding of the portion of infections which remain asymptomatic. However, based on the incidence of transmission from identified symptomatic cases to contacts, R₀ for SARS-CoV-2 ranges from 1.4 to 3²². This is higher than the estimated R₀ for 1918 pandemic influenza²³.“