References

Miller RL. Characteristics of blood-containing aerosols generated by common powered dental instruments. Am Ind Hyg Assoc J. 1995; 56:670-676
van Doremalen N, Bushmaker T, Morris DH Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. N Engl J Med. 2020; 382:1564-1567
Li RWK, Leung KWC, Sun FCS, Samaranayake L Severe acute respiratory syndrome (SARS) and the GDP. Part II: Implications for GDPs. Br Dent J. 2004; 197:130-134

COVID-19 and Dentistry: Aerosol and Droplet Transmission of SARS-CoV-2, and Its Infectivity in Clinical Settings

From Volume 47, Issue 7, July 2020 | Pages 600-602

Authors

Lakshman Samaranayake

DSc, DDS, FRCPath, FHKCPath, FDS RCS(Edin), FRACDS, FDS RCPS

Professor Emeritus, and Immediate-past Dean, Faculty of Dentistry, University of Hong Kong

Articles by Lakshman Samaranayake

Email Lakshman Samaranayake

Abstract

In the last inaugural issue of the Commentary we discussed the origins of the SARS-CoV-2, the probable reasons for its emergence, and how the virus spreads due to the rapid, inter-continental, mass transportation, as well as the human behaviour leading to deforestation and massive urbanization and environmental changes. Here, we outline the issues surrounding infectivity of the SARS-CoV-2, plus its spread through aerosols, droplets and aerosol generating procedures (AGPs) in the dental clinic milieu, as well as its viability in the ambient environment.

Article

An aerosol can be defined as a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be either natural – such as fog, mist, dust, or anthropogenic – created by humans or animals when they go through normal activities, such as speaking, sneezing, or coughing, for instance. Aerosols can also be visible, like fog, but more often invisible, like dust or pollen. Irrespective of the visibility or size, they may contain live/dead microbes and hence the term bio-aerosols. It is noteworthy that aerosols can be produced indirectly (by humans) via mechanical means, such as respirators and poorly maintained air-conditioning systems. In our context, bioaerosols are the offending agents that contribute much to COVID-19 spread.

The characteristics of bio-aerosols and their spread vary considerably, depending on numerous confounding factors. There are conflicting reports in the literature on the size of the aerosols and how long they are airborne. For instance, early researchers have classified particles <100 μm in diameter as aerosols, and those >100 μm as droplets or ‘spatter/splatter’ (Figure 1). The latter usually fall on to the ground immediately after they are expelled. The former, aerosols, on the contrary, may be entrained or suspended in the air for considerable periods, depending on the humidity, airflow, and temperature of the environment into which they are expelled, such as a dental clinic operatory or a hospital ward. Similarly, the large diameter ‘droplets’, containing millions of viral particles, can contaminate surfaces in the immediate vicinity, and spread a few metres, yet again depending on the ambient conditions, such as the airflow.

Register now to continue reading

Thank you for visiting Dental Update and reading some of our resources. To read more, please register today. You’ll enjoy the following great benefits:

What's included

  • Up to 2 free articles per month
  • New content available