1. Clinical characteristics of coronavirus disease 2019 in China;Guan;N Engl J Med,2020
2. Centers for Disease Control and Prevention. How COVID-19 spreads. Accessed October 2, 2021. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-covid-spreads.html
3. Aerosol-generating procedures and infective risk to healthcare workers from SARS-CoV-2: the limits of the evidence;Harding;J Hospital Infect,2020
4. Frangos SA. ACOEM advises suspension of routine occupational spirometry testing during COVID-19 pandemic. Accessed March 25, 2020. https://myemail.constantcontact.com/ACOEM-Advises-Suspension-of-Routine-Occupational-Spirometry-Testing-During-COVID-19-Pandemic.html?soid=1102647720683&aid=idWxyX21cJ4
5. Center for Disease Control and Prevention. COVID data tracker. Accessed October 2, 2021. https://covid.cdc.gov/covid-data-tracker/#datatracker-home