In response to growing concerns over COVID-19, Healthy Building Network (HBN) and global architecture and design firm Perkins and Will reexamined the conclusions and recommendations of our white paper, “Healthy Environments: Understanding Antimicrobial Ingredients in Building Materials,” which we co-wrote in 2017. The aim of this update is to present current information about reported or potential health and environmental impacts of antimicrobial substances as commonly used within the building industry, and to assist architects, designers, building owners, tenants, and contractors in understanding those impacts. This review reaffirms the conclusion of our March 2017 analysis: No evidence yet exists to demonstrate that products intended for use in interior spaces that incorporate antimicrobial additives actually result in healthier populations. Further, antimicrobials may have negative impacts on both people and the environment.