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School Ventilation: A Vital Tool to Reduce COVID-19 Spread

School Ventilation: A Vital Tool to Reduce COVID-19 Spread | report cover
Paula J. Olsiewski, Richard Bruns, Gigi Kwik Gronvall, William P. Bahnfleth, Gunnar Mattson, Christina Potter, Rachel A. Vahey
Date posted:
May 26, 2021
Publication type:
The Johns Hopkins Center for Health Security
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Many kindergarten through 12th grade (K-12) schools in the United States do not have good ventilation. This is a longstanding problem with demonstrably negative effects on student learning. We can and should act to fix this to ensure good indoor air quality for all students, educators, and school staff. During the COVID-19 pandemic, it is even more important that ventilation problems in K-12 schools be addressed now. Along with other mitigation measures, improvements in ventilation in K-12 schools can decrease the risk of SARS-CoV-2 spread.

The US Centers for Disease Control and Prevention (CDC) has provided guidance for safe in-person learning for K-12 schools, recommending a layered approach with multiple public health mitigation measures in place. In addition to testing programs and the potential for vaccination, mitigation measures include use of masks, physical distancing, handwashing and respiratory etiquette, contact tracing, and cleaning and maintaining healthy facilities.

This report focuses on an important component of cleaning and maintaining healthy facilities: ventilation. Improvements in ventilation can help reduce risk of transmission of SARS-CoV-2 and other infectious diseases and improve students’ overall health and ability to learn. On May 7, 2021, the CDC highlighted the important role of SARS-CoV-2 aerosol transmission in the pandemic, which further underscores the need for improvements to air quality to reduce the spread of COVID-19.

In this report, we consider the impact of the COVID-19 pandemic on children, families, and educators; review the evidence that improvements in ventilation reduces risks of disease transmission; and summarize current ventilation guidelines. While ventilation improvements may often be perceived as a complicated and expensive investment, we demonstrate in a cost-effectiveness analysis comparing ventilation with enhanced (“deep”) cleaning that ventilation improvements are a cost-effective public health measure. As new, potentially more transmissible variants of SARS-CoV-2 continue to emerge, broad improvements in indoor air quality are important for reducing transmission. Improvements to ventilation are a good use of the COVID-19 relief funds provided to K-12 schools.

To produce this report and recommendations, we interviewed 32 experts in air quality, engineering, education policy, and communications, as well as teachers at schools that have been open for in-person learning during the pandemic. We examined relevant peer-reviewed scientific literature and engineering best practices for indoor air quality as well as specific guidance for K-12 schools issued by the CDC and expert industry organizations. We also hosted a webinar featuring experts in indoor air quality, engineering, and schools to highlight their expertise and provide recommendations for what can be done now to reduce SARS-CoV-2 transmission through improvements in ventilation and to add to the mitigation measures that schools are already taking.

A broad conclusion of this research is that the benefits to investing in healthy air in schools have the potential to outlast the COVID-19 pandemic. Improved ventilation may give children and school staff healthier indoor air quality for decades in the future, providing a healthier environment for nonpandemic times and potentially reducing risks in future infectious disease outbreaks.



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