Evaluation of Interventions to Improve Ventilation in Households to Reduce Risk for Transmission of Severe Acute Respiratory Syndrome Coronavirus 2

Carbon Dioxide Monitoring Demonstrates Variations in the Quality of Ventilation on Public Transportation Buses and University Student Shuttle Vans and Identifies Effective Interventions

Background

There is a risk for transmission of severe acute respiratory syndrome 2 (SARS-CoV-2) and other respiratory viruses in motor vehicles, particularly if ventilation is inadequate.

Methods

We used carbon dioxide monitoring to examine the quality of ventilation in several public transportation buses and in university student shuttle vans in the Cleveland metro area during peak and non-peak travel times. Carbon dioxide levels above 800 parts per million (ppm) were considered an indicator of suboptimal ventilation for the number of people present. In the shuttle vans, we evaluated the impact of an intervention to improve ventilation.

Results

In large articulated buses with 2 ventilation systems, carbon dioxide concentrations never exceeded 800 ppm, whereas in standard buses with 1 ventilation system concentrations rose above 800 ppm during peak travel times and on some trips during non-peak travel times. In shuttle vans, the ventilation system was not turned on during routine operation, and carbon dioxide levels rose above 800 ppm on all trips during peak and non-peak travel times. In the shuttle vans, an intervention involving operation of the existing ventilation system resulted in a significant reduction in carbon dioxide levels (mean concentration, 1,042 no intervention versus 785 with intervention; P < 0.001).

Conclusions

Our findings demonstrate substantial variability in the quality of ventilation in public transportation buses and university shuttle vans. There is a need for efforts to assess and optimize ventilation in motor vehicles used for public transportation to reduce the risk for aerosol-mediated transmission of respiratory viruses. Carbon dioxide monitoring may provide a useful tool to assess and improve ventilation.

High technology and low technology measures to reduce risk of SARS-CoV-2 transmission

During the coronavirus disease 2019 (COVID-19) pandemic, a variety of low technology and high technology measures have been proposed to reduce the risk for transmission. Identifying those measures likely to be useful in reducing viral transmission without undue expense or potential for adverse effects has been a challenge for infection control programs. The challenge has been compounded by the lack of tools that can be used to assess the risk for viral transmission in different settings. This review discusses practical tools that can be used to assess ventilation and airflow and evaluates some of the low technology and high technology measures that have been proposed as control measures for COVID-19. Some typical questions posed to infection control programs during the pandemic are presented to illustrate real-world application of the concepts being discussed.