1. Public Health England.COVID‐19: Guidance for infection prevention and control in healthcare settings. Version 1.1. 27 /03/20. COVID‐19: infection prevention and control guidance.2020.https://www.gov.uk/government/publications/wuhan-novel-coronavirus-infection-prevention-and-control(accessed 25/03/2020).
2. Guidance on the use of respiratory and facial protection equipment
3. Centers for Disease Control and Prevention.Airborne contaminant removal.2020.https://www.cdc.gov/infectioncontrol/guidelines/environmental/appendix/air.html#tableb1(accessed 21/05/2020).
4. Mycobacterium tuberculosis in health‐care facilities;Morbidity and Mortality Weekly Report,1994