Assessing the Transmission of Infectious Aerosols in the Indoor Environment: Next Steps for Future Research and Policy

Day 1: Thursday April 4, 2024 

Welcome and Introductions 

• Gigi Gronvall, Associate Professor, Johns Hopkins Bloomberg School of Public Health, Senior Scholar, Johns Hopkins Center for Health Security
• Paula Olsiewski, Contributing Scholar, Johns Hopkins Center for Health Security 

 Topic 1:  Applications of Airborne Exposure Science
Moderator: Gigi Gronvall, Johns Hopkins Center for Health Security, Department of Environmental Health and Engineering 

This session will focus on the practical applications of airborne infection risk analysis. Speakers will discuss engineering control design, administrative control planning, (such as when to apply infection risk management mode in ASHRAE 241), public health actions and regulatory gaps. Speakers will present for 10-12 minutes, leaving time for clarifying questions before the next discussion section.   

Panelists:

• Bill Bahnfleth, Professor of Architectural Engineering, Pennsylvania State University
• Jessica Green, Advanced Research Projects Agency for Health
• Lew Radonovich, Deputy Director, Respiratory Health Division, Centers for Disease Control and Prevention
• Kazukiyo Kumagai, Air Quality Section Chief at the California Department of Public Health 

Topic 2: Generation of infectious aerosols
Moderator: Paula Olsiewski, Johns Hopkins Center for Health Security  

This session will focus on the generation of indoor infectious aerosols. While there is a lot of variability, discussion will focus on how much infectious material is produced at the source, how much variability there is from person to person in generating virions or bacteria, the ranges one might expect for different pathogens, and what observations may be generalized across pathogens and environments. Speakers will discuss the generation rates, size distribution, and emission rates of respiratory pathogens; confounding factors related to the pathogen, the host, or the environment; and quanta emission rates. Discussion should also include research gaps and suggestions for addressing them. Speakers will present for 10-12 minutes, leaving time for clarifying questions before the next discussion section. 

Panelists:

• Don Milton, Professor of Environmental Health, Applied Environmental Health, University of Maryland
• Lidia Morawska, Distinguished Professor and Australian Laureate Fellow, School of Earth and Atmospheric Sciences, Queensland University of Technology
• Giorgio Buonanno, Professor Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio 

Topic 3: Fate and Transport of Infectious Particles
Moderator: Gigi Gronvall, Johns Hopkins Center for Health Security, Department of Environmental Health and Engineering 

Building on Topic 2, this session will consider how susceptible hosts are exposed to infectious aerosols emitted by infectors. Speakers will address the aerosol characteristics as measured near and far field; the exposure pathway from the “infector” to “receptor,” and where particle deposition occurs; the effect of air distribution and natural removal mechanisms including deposition and inactivation; engineering controls, including dose response to disinfectants; and research needs to address gaps. Speakers will present for 10-12 minutes, leaving time for clarifying questions before the next discussion section. 

Panelists:

• Yuguo Li, Chair Professor of Building Environment Department of Mechanical Engineering, and Associate Dean of Research, University of Hong Kong
• Brian Damit, Project Manager and Research Scientist Johns Hopkins Applied Physics Laboratory
• Jordan Peccia, Professor and Chair of the Department of Chemical and Environmental Engineering, Yale University  

Day 2: Friday April 5, 2024 

Topic 4: Risk Estimation
Moderator: Paula Olsiewski, Johns Hopkins Center for Health Security 

Speakers will discuss the current models and their limitations, including Wells-Riley and others. They will address the input data requirements, sources of uncertainty, exposure scenarios, and discuss absolute or relative risk. Research needs will be highlighted. Speakers will present for 10-12 minutes, leaving time for clarifying questions before the next discussion section. 

Panelists:

• Chuck Haas, Chair Professor of Environmental Engineering, Department of Civil Architectural, and Environmental Engineering, Drexel University
• Ben Jones, Associate Professor, Department of Architecture and Built Environment, University of Nottingham
• David Fisman, Professor at the Division of Epidemiology and Institute for Pandemic, Dalla Lana School of Public Health, University of Toronto
• Pawel Wargocki, Professor, Department of Environmental and Resource Engineering, Technical University of Denmark 

Working towards a paper: 

• What should the main messages of the paper be? 
• Who are the most important audiences of this paper? 
• What are key research needs that need to be addressed, and how should they be prioritized? (Thought experiment: If another pandemic were to emerge, and you were able to go back in time 8 months with an extensive research budget, what would you prioritize? Does this change if it were bacterial or viral pandemic?) 
• Tour de table