COVID-19: Transmission and environment

Partnership for Research in Occupational, Transport, Environmental COVID Transmission (PROTECT).


Since the appearance of SARS-CoV-2, researchers have been attempting to identify the most important routes of transmission for the virus. This information is critical to enable the development of effective strategies to block these routes and enable a return to a more normal routine in all aspects of life.

At present, we know that the virus is transmitted through three main routes:

  • Person-to-person;
  • In the air;
  • On surfaces.

However, we do not yet understand the relative importance of each of these three routes, and how environmental conditions can alter the dynamics of transmission in any given scenario.

The knowledge gaps include:

  • The generation, emission and dispersion of virus-containing droplets;
  • The viral load and particle size distribution of aerosols generated during a range of activities and the infective dose of virus required to initiate infection;
  • The critical factors required for environmental survival;
  • The key risk factors responsible for outbreaks at the enterprise, sector and local level;
  • How effective control measures can be developed that enable resumptions of normal activities at the sector level (for example: transport, performing arts, care homes, educational).

This study, which forms part of the wider Covid-19 National Core Programme , aims to address these knowledge gaps through six key themes.