Table 1 Model assumptions for evaluating the cost-effectiveness of improving ventilation in commercial spaces for the prevention of SARS-CoV-2

The standardized room of 1000 square-foot with a ceiling height of 9 feet has 0.8 air changes per hour, primarily from the door opening and closing and the food vent running

For lunch, the restaurant is open for 3 h. Each of 30 occupants is seated for one hour. We modeled 3 consecutive lunch events each for a duration of 1 h. In each event, the restaurant is at the full seating capacity

For dinner, the restaurant is open for 6 h. Each of 30 occupants is seated for 1.5 h. We modeled 4 consecutive dinner events each for a duration of 1.5 h. In each event, the restaurant is at the full seating capacity

Between lunch and dinner hours, the restaurant is closed for enough time so that the virus concentration in the indoor air dropped to zero as workers opened doors and moved throughout the space

The restaurant is operating 7 days a week with similar lunch and dinner hours

The model is built under well-mixed conditions for an infected individual present in an indoor space and there is dynamic airflow in unpredictable patterns associated with the movement of people and an overhead fan [18, 19]

We assumed that transmission through the close-range mode—that is, when infectious aerosols were inhaled directly from the exhaled breath of an infected individual by a susceptible person in its vicinity—is on par between the comparison arms. Thus, only infection through the inhalation of accumulated aerosols, often referred to as the long-range mode of airborne transmission, is modeled and close-range transmission is not modeled [18, 19]

We assumed that infected symptomatic Covid-19 cases would quarantine for 14 days. We also assumed those infected cases who required hospitalizations would quarantine for 21 days

All wages were valued at the median hourly wage in the US [14]