Protecting First Responders from Secondary Exposure Act of 2021 This bill expands the allowable uses of grant funds under the Comprehensive Opioid, Stimulant, and Substance Abuse Program administered by the Department of Justice. Specifically, the bill allows grants to be used for purchasing containment devices for first responders and training first responders on the use of containment devices to prevent secondary exposure to fentanyl and other potentially lethal substances.