There has been a lot of speculation if Coronavirus spreads through air or not. Before knowing the answer, it is important to understand how Coronavirus spreads when an infected person coughs or sneezes. When we cough or sneeze several droplets are expelled out of our respiratory tract. Sneezing creates more droplets than coughing given the force generated by sneezing. Depending on the size of these particles, Infectious Disease Society of America (IDSA) classifies them as ‘respirable particles’ if they are smaller than 10 microns, ‘inspirable particles’ if they are above 10 microns. The smaller respirable particles can go through our nose, throat and straight into the lungs. The larger inspirable particles usually reach our nose and sinuses but do not reach our lungs. When we cough or sneeze, almost all the expelled particles are larger inspirable particles, very few smaller respirable particles are expelled out.
When an infected person coughs or sneezes, the probability of Coronavirus spreading through the air is very minimal. If the infected person is coughing their lungs out in a small closed room and has large quantities of sputum production, the risk of airborne spread may be slightly higher. It is always advisable to have open windows when the infected person is quarantined in a room. Healthy individuals should stay away from the quarantined person until active symptoms resolve. In the communities, using regular face masks is more than enough to prevent Coronavirus from spreading from person to person. Regular face masks can filter all the larger inspirable particles and safely protect individuals.
In a hospital setting, during certain procedures like intubation, bronchoscopy, airway suctioning or when patients are on BIPAP, CPAP, high-flow nasal cannula or when nebulizations are administered, more smaller respirable particles are generated. During these procedures and treatments, Coronavirus can spread through air. It is imperative to wear N95 respirator masks to prevent airborne spread. Even in a hospital setting, unless patients are going through the above procedures and treatments, they may be kept in droplet isolation rooms where only regular face masks are used. N95 respirator masks may not be needed for all Coronavirus infected persons.
Based on the study published in the New England Journal of Medicine, small aerosols may last in the air for around three hours. If the infected person uses a CPAP machine or a nebulizer at home, they should be under strict quarantine with closed doors. If any healthy individual walks into the quarantine room when the infected person is on CPAP machine or using a nebulizer, it is advisable to wear an N95 respirator mask. As smaller aerosols may last up to three hours after nebulizations are used, N95 respirator mask may need to be used if entering the room during this period.
In summary, Coronavirus does not usually spread through air in normal circumstances. During certain procedures and treatments, it may spread through air. However, most of these procedures and treatments are carried out in a hospital setting except for CPAP or nebulizers. If the infected person is using CPAP or nebulizers at home, there is a possibility of spread through the air. A regular face mask is enough to prevent Coronavirus infection in the communities. It may be advisable to use N95 respirator masks if the infected person is using CPAP or a nebulizer machine.