Background and Objective: Exposure to pathogenic bioaerosols presents a hazard to workers and the general population, as demonstrated during the COVID-19 pandemic. Few resources and tools are available for assessing transmission risk at the workplace and designating appropriate controls to reduce the risk of transmission, which is highlighted by the lack of available standards and regulations designed specifically for conducting workplace quantitative microbial risk assessments (QMRAs). Based on existing literature and tools, a flexible semi-quantitative microbial risk assessment (sQMRA) framework for health and safety (H&S) practitioners was developed to assess and manage occupational exposure to bioaerosols in the workplace.

Methods: A literature search was performed using PubMed and WorldWideScience databases and the Google Scholar search engine to identify peer-reviewed and publicly available English-language literature and government documents published before October 19, 2021 that discuss or evaluate the current state of the science regarding QMRA in occupational settings. Publicly available literature, reports, policies, and documents meeting predefined criteria were used to develop a sQMRA framework. Next, this framework was applied to a hypothetical occupational SARS-CoV-2 exposure scenario in which quantitative and semi-quantitative inputs allowed for the selection and refinement of controls in order to reduce exposure.

Key Content and Findings: A total of 22 relevant publications and government documents were identified that provided key points relating to each risk assessment step, which allowed for the development of a sQMRA framework for H&S practitioners.

Conclusions: An easily implementable and adaptable sQMRA framework was developed for H&S practitioners. This framework aims to assist practitioners in taking a systematic, data-driven, and flexible approach to risk-based decision making for assessing and managing bioaerosol exposures in the workplace. Applying and optimizing this framework in occupational settings will allow H&S practitioners to better respond to the next outbreak or pandemic in the workplace.

Keywords: Quantitative microbial risk assessments (QMRAs); bioaerosol; COVID-19; outbreak; pathogen