The National Academies of Sciences, Engineering, and Medicine (NASEM) Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats released an expert consultation that notes that while specific research on COVID-19 is limited, results of available studies support the possibility that viral particles can be spread via bioaerosols generated directly by exhalation of patients with COVID-19.
The Standing Committee responds to a question about whether COVID-19 could be spread via conversation. The consultation summarizes several studies done on patients with COVID-19 and other coronaviruses.
In one study, University of Nebraska researchers collected air and surface samples from 11 isolation rooms where 13 people who tested positive for COVID-19 were staying. Their results suggested identification of genetic material from the virus that causes COVID-19 in air samples found in this study provides limited evidence that some potential for airborne transmission exists. The researchers note however that this does not confirm that this virus spreads in an airborne fashion and they are doing further research to determine if live culturable virus was captured in this study.
Another study referenced that indicated that surgical face masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic individuals is based on a study patients with SARS-CoV and MERS-CoV not SARS-CoV2 (COVID-19).
The expert consultation notes that although the studies with SARS-CoV2 are limited, the existing studies are consistent with evidence of aerosolization of virus with normal breathing. This does not prove this method of transmission, but it does not rule it out.