Some thoughts from active scientists on Twitter about COVID-19 by aerosol scientists and indoor air experts @linseymarr @CathNoakes @j_g_allen @jljcolorado @amgcarlton (1/)

There is a historical bias against aerosols for a few reasons (can't see them, anti-miasma reaction, get people to focus on cleanliness), but there is at least as much, if not more, scientific evidence for transmission of SARS-CoV-2 by aerosols compared to any other route. (2/)

Virus-laden aerosols produced in speech (<10 microns) can remain viable for hours, travel much further than 6 ft, and build up in crowded poorly ventilated rooms. (3/)

Aerosol risk is greatest where multiple people spend significant time together in poorly ventilated spaces. Focus on how to mitigate those spaces as a priority, and before winter. (4/)

There is NO safe social distance in a poorly ventilated room. People must wear masks even if they can remain 6 ft apart indoors. The standard recommendation still holds that the further apart, the better. (5/)

We know aerosols can cause outbreaks in rooms with poor ventilation. Aerosols are much more concentrated when talking in close proximity (like talking to smoker in same room). Logical consequence that a large fraction of close contact transmission occurs through aerosols. (6/)

High profile outbreaks, from cruise ships to restaurants, to camps and choir practice, share telltale signs that airborne transmission is happening. (7a/)

Healthy building strategies like enhanced ventilation and filtration must be added to the suite of the foundational control measures, alongside mask wearing, hand-washing, and distancing. (7b/)

Once virus-laden aerosols becomes airborne and linger in the air for hours, everyone in the room shares the same air and is at risk to exposure by asymptomatic individuals that are simply speaking. (8/)

Re-opening plans focus on droplets & cleaning - it's easy, makes people feel good & cheaper than retrofitting HVAC systems. Indoor chemistry community shows this goes against healthy air: Creates poor air quality & maybe even makes people more susceptible to COVID-19. (9/end)

Aerosol/droplet size is crucial as size determines 1) how long they remain in the air, 2) how far they travel, 3) how deeply they penetrate the lungs, 4) mode of transmission (contact vs inhalation), and 5) severity of disease.

Link to NASEM Workshop recording on Airborne Transmission of SARS-CoV-2 https://www.nationalacademies.org/event/08-26-2020/airborne-transmission-of-sars-cov-2-a-virtual-workshop

Have questions about protecting yourself against SARS-CoV-2 and COVID-19? See FAQ: https://tinyurl.com/FAQ-aerosols