An estimation of airborne SARS-CoV-2 infection transmission risk in New York City nail salons.

Amelia Harrichandra,Brian Pavilonis,A Michael Ierardi

doi:10.1177/0748233720964650

Abstract

Although airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from person-to-person over long distances is currently thought to be unlikely, the current epidemiological evidence suggests that airborne SARS-CoV-2 infection transmission in confined, indoor spaces is plausible, particularly when outdoor airflow rates are low and when face masks are not utilized. We sought to model airborne infection transmission risk assuming five realistic exposure scenarios using previously estimated outdoor airflow rates for 12 New York City nail salons, a published quanta generation rate specific to SARS-CoV-2, as well as the Wells–Riley equation to assess risk under both steady-state and non-steady-state conditions. Additionally, the impact of face mask-wearing by occupants on airborne infection transmission risk was also evaluated. The risk of airborne infection transmission across all salons and all exposure scenarios when not wearing face masks ranged from <0.015% to 99.25%, with an average airborne infection transmission risk of 24.77%. Wearing face masks reduced airborne infection transmission risk to between <0.01% and 51.96%, depending on the salon, with an average airborne infection transmission risk of 7.30% across all salons. Increased outdoor airflow rates in nail salons were generally strongly correlated with decreased average airborne infection transmission risk. The results of this study indicate that increased outdoor airflow rates and the use of face masks by both employees and customers could substantially reduce SARS-CoV-2 transmission in New York City nail salons. Businesses should utilize multiple layers of infection control measures (e.g. social distancing, face masks, and outdoor airflow) to reduce airborne infection transmission risk for both employees and customers.

Highlights

In the midst of the ongoing coronavirus disease 2019 (COVID-19) pandemic, an understanding of the potential route(s) of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for causing COVID-19, is of critical importance in the design and implementation of effective infection control measures
Wearing face masks resulted in an airborne infection transmission risk ranging from
In a similar study focusing on the role of ventilation in the spread of COVID-19, it was concluded that reducing occupancy by 50% reduced the risk of airborne infection transmission by 6.7% based on a 90-min exposure duration in a restaurant, with similar dimensions to the nail salons; it was demonstrated in this study that increasing the ventilation rate by approximately 27% could achieve the same rates of airborne infection transmission risk reduction (Sun and Zhai, 2020)

Summary

Introduction

In the midst of the ongoing coronavirus disease 2019 (COVID-19) pandemic, an understanding of the potential route(s) of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for causing COVID-19, is of critical importance in the design and implementation of effective infection control measures. At the time of publication, the state-ofthe-science as reported by the US Centers for Disease Control and Prevention (CDC) suggested that while adequate hygiene and disinfection are important, indirect transmission via fomites “is not thought to be the main way the virus spreads” (CDC, 2020c). A growing body of epidemiological evidence indicates that this novel human coronavirus is primarily spread from person-to-person via respiratory droplets or droplet nuclei, such that the risk of airborne SARS-CoV2 infection transmission is likely highly dependent on both the duration of exposure and proximity to an infectious individual. Many COVID-19 outbreaks have originated in indoor environments, including restaurants (Lu et al, 2020), churches (Yong et al, 2020), and cruise ships (Moriarty et al, 2020), where individuals are generally in close proximity with one another for extended periods of time and are talking, shouting, and/or singing—all activities that tend to produce respiratory droplets. Recommendations for universal (and proper) use of face masks and social distancing among the general public have proven effective in curtailing community spread of COVID-19 (Chu et al, 2020)

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