I see some potential flaws in this study: They are using a piezo disk to launch the particles into the air, might that alone kill or weaken the virus? They are putting an electric charge on the particles, could that kill or weaken the virus? They are holding the particles in an electric field, could that kill or weaken the virus? This seems to be a new method of suspending particles in air for long periods of time and I don't see any validation of this suspension method. They are still seeing 15% infectivity after 20 minutes and the curve seems very flat at that point in figure 1A, which suggests infection is still possible, perhaps for much longer periods of time (which they did not test).<p>Also some of the superspreading events and known cases of indoor spread seem to contradict these results, though I haven't seen detailed data on the time frame of those events. The virus seems able to live for periods much longer than 20 minutes on surfaces as well according to early research, which doesn't seem to jive. Another criticism of this study I've seen is that a person spreading the virus keeps putting new virus into the air, so even if the virus does die in 5-20 minutes, it is possible the total live virus in the air keeps growing over time as long as that person is still there. Without a comparison between the virus death rate and the rate of introduction of new particles, even if this data is correct, it's not useful for making any recommendations except perhaps saying a recently emptied space is safe after 20+ minutes. I'm not sure you can even say that since they didn't test beyond 20 minutes.<p>I'd like to see the apparatus validated, perhaps with a much safer virus and comparing it to an actual person sneezing, talking, coughing and sampling the air from the room they are in periodically.