The National Academies

TCRP E-13 [Completed]

COVID-19 and Transit Air Quality Protections (Insight Event)

  Project Data
Funds: $120,000
Research Agency: Versar, Inc.
Principal Investigator: Adria Diaz
Effective Date: 6/21/2022
Completion Date: 6/22/2022
Comments: Insight Event was hosted in the summer of 2022. Session records are posted online.


The Transit Cooperative Research Program (TCRP) provides practical solutions to challenges faced by transit industry practitioners. Not all challenges lend themselves to applied research or to published solutions due to their dynamic or unsettled nature, lack of maturity, or because the state of knowledge or practice is still evolving. Nonetheless, the transit industry would benefit from a deeper understanding and dialog on many of these challenges even if an immediate solution is not practical.

Established in 2020, TCRP Insight Events convene transit-industry leaders and subject-matter experts (SMEs) in various fields to encourage discussion and promote broader and deeper insight on topics of significance to transit operators.

Consistent with the National Academies of Sciences, Engineering, and Medicine, the definition of a convening event, such as a TCRP Insight Event, is intended to create a collaborative environment that fosters dialogue across sectors, institutions, and industries. Insight Events are selected by the TCRP Oversight Committee (TOPS). It is expected that each event will take place within 12 months of TOPS funding authorization. The Transportation Research Board (TRB) of the National Academy of Sciences, Engineering, and Medicine will follow established TRB guidelines for the conduct of each event.

TCRP applied research projects publish contractor-authored reports. TCRP Insight Events are convening events of the National Academies of Sciences, Engineering, and Medicine and we may publish summaries of the events. TCRP research cannot produce policy recommendations or advice to federal agencies or to Congress.

A TCRP Insight Event may result in webinar-style video recordings, web content, podcasts, infographics, or meeting notes. Other products, such as event summaries, a forum or workshop in brief, or proceedings, are possible through an Academies report review and then published by the National Academies.

Although TCRP Insight Events do not produce solutions themselves, they illuminate issues that need attention. Each TCRP Insight Event will have topic experts on the planning panel to design and develop activities for the event. Usually, planning panel members are selected based on each individual’s expertise, but other considerations may be a factor. Government officials and industry associations may serve in ex officio capacity on planning panels.

Among other outcomes, TCRP Insight Events may lead to opportunities for further work that are appropriate for TCRP research projects. For example, the activities of a TCRP Insight Event may result in one or more TCRP problem statements, which may lead to funding a TCRP applied research project, legal study, or synthesis of practice.


According to the World Health Organization (WHO) definition, COVID-19 is an infectious disease caused by a novel coronavirus. The COVID-19 virus spreads primarily through droplets of saliva or discharge from the nose when an infected person coughs or sneezes.  These droplets, which are small viral particles, can stay suspended in the air for long periods of time especially in closed spaces.  COVID-19 has been known to have been transmitted during the course of transit occupancy, causing the illness and deaths of public transportation workers and, probably' the passengers as well. The risk has been demonstrated by contact tracing, which led to identification of multiple clusters of infection tracing back to bus trips on vehicles with recirculated air contaminated with SARS-CoV-2 (the virus that causes COVID-19).  Due to the concerns over transmission of COVID-19, transit has suffered a decline in ridership. In order to increase ridership and get back to some type of normal, the industry needs to improve the air quality inside transit vehicles and reassure the public that traveling in transit vehicles is safe.  Improving the quality of air inside transit vehicles, will also protect workers and riders against any airborne infections including the seasonal flu. 


The objective is to assist TCRP in conducting an Insight Event to understand how air quality inside transit vehicles might contribute to the spread of infections. The purpose of this convening event is to allow transit and stakeholders to share their knowledge about the issue of air quality inside vehicles, and help identify possible solutions to the problem and/or areas of research to be undertaken in a future TCRP project.


Status: The Insight Event was held June 21st and 22 of 2022. The recordings of each of the sessions are located here. Conference proceedings to follow. 

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