FAQ for Preparing for CBRNE Emergencies at Mass Gatherings

July 08, 2026 | Kelsey Tillema, Adrianna Evans

As the United States prepares to host multiple high-profile or international mass gathering events in the coming years, preparedness professionals should revisit and strengthen plans to address complex and high-impact threats. Among the most critical are Chemical, Biological, Radiological, Nuclear, and Explosive (CBRNE) hazards — a grouping of high-consequence threats with potential to significantly impact public safety and health:

Chemical agents (toxic chemicals, nerve agents).
Biological agents (harmful bacteria, viruses).
Radiological materials (accidental or intentional dispersion of radioactive material, including from nuclear power plants).
Nuclear incidents (nuclear detonations).
Explosives (intentional or accidental blasts).

Human health could be greatly impacted, with the potential for the following consequences:

Acute injuries (burns, trauma, poisoning, radiation sickness) and mortality, along with other long-term conditions (cancer, organ damage, etc.).
Psychological impacts such as PTSD, anxiety, and depression, among other long term mental health impacts.
Strain on health care and public health systems, including disruptions to hospital services and the supply chain.

As jurisdictions prepare for the 2026 FIFA World Cup and future mass gathering events, this resource serves as a broad overview of the roles and responsibilities of public health in relation to a CBRNE incident. This information is not comprehensive but is intended to provide consideration and further resources for planning efforts.

According to the Centers for Disease Control (CDC), a mass gathering is typically defined as “large numbers of people at a specific location for a specific purpose, with the gathering being large enough to strain local resources. Travelers to mass gatherings face unique risks because these events are associated with both communicable diseases (from crowding, poor hygiene practices, sanitation issues, and population dynamics [i.e., specific events attract at-risk groups]) and non-communicable conditions (e.g., temperature extremes, stampedes, environmental hazards, and challenging security situations).”

With the FIFA World Cup, Super Bowls, summer Olympics, and the United States 250th Anniversary on the horizon, mass gathering events will take place in many jurisdictions. While these events may be the focus of planning and preparedness efforts, it is important to also maintain awareness of related gatherings that may occur in tandem, but in different locations. This could include watch parties, festivals, and other spontaneous gatherings that can similarly strain public health, health care, and emergency response systems.

Public health agencies operate under Emergency Support Function 8 (ESF-8, Public Health and Medical Services) as part of the Federal Emergency Management Agency (FEMA) National Response Framework. In this capacity, public health may serve as a lead or supporting role to provide structure needed to address medical and public health needs during the preparedness, response, and recovery of a CBRNE incident in a mass gathering setting.

In the preparedness phase, public health focuses on planning and maintaining specific response guidance and annexes for CBRNE-related events. In each type of plan, it will be important to coordinate with other response partners, such as emergency management, health care, fire and first responder services, law enforcement, and transportation agencies. With these partnerships, health agencies may need to consider medical surge and resource allocation, communications, incorporating behavioral health needs and at-risk populations, and creating long-term recovery frameworks for after a response. When responding, plan activation and surveillance, contact tracing, medical countermeasure (MCM) dispensing, and other non-pharmaceutical interventions may be initiated.

Agencies should also consider sheltering, evacuation, and transportation concerns. The specifics of the incident and the materials involved will drive instructions to the public. Clear instructions for the public are critical. Key messages could include the following:

Unless told to evacuate, one should always shelter in place.
If evacuation is ordered, listen to the instructions.
Community members may be sent to a "safe" location or home to initiate self-decontamination, then may report to a community reception center later.

Partnerships with public and private transit systems can be valuable for evacuation and mass transportation. Non-governmental entities such as shuttle and bus companies or faith-based organizations may be able to supplement governmental systems. For people with access and functional needs, long-term care facilities, retirement communities, paratransit companies, schools, and health care facilities may be able to assist.

Partnerships are critical for identification and detection of CBRNE incidents. Detection of CBRNE materials relies on several different mechanisms. Monitoring systems such as sensors and specialty on-site tools can detect radiological, chemical, and biological agents. Intelligence sharing and law enforcement processes may also be used to aid in detection. Emergency departments, poison control centers, and public health laboratories can also aid in identifying unusual symptom clusters and confirming the presence of harmful agents.

Notification and information may come from several different sources. CDC’s Health Alert Network can share urgent information related to public health incidents with public health agencies, clinicians, laboratories, and response staff. Responders can also access the secure CBRNResponder platform managed by FEMA for all-hazards data sharing for response agencies. Additionally, each state has an FBI Weapons of Mass Destruction Coordinator. As a lead agency, the FBI can provide information through the state homeland security advisor and fusion centers.

Principles of crisis and emergency risk communication (CERC) remain critical during CBRNE events. However, communications in these scenarios may be complicated by high levels of uncertainty and fear. The public nature of mass gatherings may accelerate the spread of fear, speculation, and rumors. Tackling misleading information will be an important consideration. Public Information Officers will be critical internal experts to guide communication strategies. In CBRNE scenarios, health agencies can work closely with (internal or external) subject matter experts on specific materials or agents to ensure accuracy in health messaging. Agencies can create pre-scripted, approved messages before an incident occurs to reduce the time needed to release communication to the public.

Health agencies can rely on the six CERC principles to guide messaging: be first, be right, be credible, express empathy, promote action, and show respect. During a crisis, people will have a lot to think about — they may only be able to remember or process a few key messages, so it is important to prioritize and be brief. It can also be helpful to keep messages in groups of three.

Special care should be taken to assess personal protective equipment (PPE) and medical equipment needs for different CBRNE scenarios to maintain adequate inventory. Staff should maintain and refresh training on triage, PPE, and MCM response protocols and scenarios. Agencies should also review processes for requesting CHEMPACK and Strategic National Stockpile assistance, and maintain contact with federal, state, and local partners in these programs. Scenarios can evolve, so it is important to continually monitor and reassess PPE use.

Agencies should connect with their health care partners to collaborate on expanding capacity for a mass casualty incident. Surge plans for emergency departments and intensive care units should be outlined, along with strategies for scenarios such as decontamination, trauma and blast injuries, mass poisoning, etc. Physical injuries may make up a significant portion of casualties so being prepared to manage these injuries is key. In chemical scenarios, it is important to consider PPE and decontamination ahead of addressing critical injuries to avoid chemical injury to health care providers. Conversely, in radiation scenarios, it is important to consider life saving measures before decontamination.

Additionally, it’s important to identify and contact subject matter experts in specialized areas. Whether it’s radiation safety professionals, toxicologists, health care partners, or trauma and burn centers, connecting with experts ahead of time and maintaining relationships will aid in a more rapid and efficient response.

Decontamination processes may vary for different CBRNE scenarios. Chemical decontamination may involve unique resources to remove the contamination. Either dry and/or wet decontamination may be necessary depending on the type of contamination. The Center for the Biomedical Advanced Research and Development Authority has worked to develop evidence-based methods guidance for chemical decontamination. The Primary Response Incident Scene Management shares detailed guidance for response to chemical incidents. The recommended “triple protocol” can remove up to 99.9% of chemical contamination. More information and resources are available on the center’s website.

In radiation decontamination, removal of outer clothing and washing with soap and water are required to remove contamination. It is important to avoid abrasive materials that may cause absorption into the skin. People may be able to self-decontaminate using resources they have at home, reducing the number of people who may need to be decontaminated by professionals. A shower, change of clothes, and disposal of contaminated clothing is a simple recommended process for at-home self-decontamination. Health agencies support decontamination and population monitoring through Community Reception Centers. CDC has created many resources to support jurisdictions in standing up Community Reception Centers. To find trainings, guidance documents, planning tools, and other resources such as tabletop exercises, check out CDC’s Radiation Emergencies website.

As in any emergency, it is important to consider people with access and functional needs in CBRNE scenarios. For CBRNE scenarios, there are special considerations for children, pregnant women, people with disabilities, older adults, people who speak English as a second language, and other groups. Children, pregnant women, people with disabilities, and older adults may have higher risk of health impacts for specific chemicals, biological agents, or radiation exposure. They may also be at higher risk of psychological impacts following emergencies. In sheltering, evacuation, and decontamination, families, caregivers, and service animals should stay together whenever possible. Any physical spaces, communications, and virtual platforms should be assessed for accessibility barriers. Decontamination plans should include considerations for service animals, assistive devices (i.e., wheelchairs, communication devices), and people who may need assistance with decontamination procedures. Planning should include extra time and flexibility for these groups to go through decontamination processes. Understanding the language and culture surrounding the mass gathering will be hugely beneficial to planning for communications as well. Access and functional needs training promotes workforce readiness to address the needs of different groups. Staff may benefit from training in disaster behavioral response, disability etiquette, basic American Sign Language, and cultural sensitivity.

Health agencies can learn more about considerations for access and functional needs through resources from the American Academy of Pediatrics, the National Association of State Animal and Agricultural Programs, the Radiation Injury Treatment Network, Pediatric Disaster Centers for Excellence, and more.

A robust response relies on building strong relationships with your partners before a crisis can occur. Key partners can include:

Associations and national organizations, such as the American College of Medical Toxicology, the American Burn Association, America’s Poison Centers, the Conference of Radiation Control Program Directors, and the Radiation Injury Treatment Network. Many of these organizations coordinate large networks of subject matter experts in toxicology, radiation safety, epidemiology, clinical guidance, and treatment protocols. Through these associations, jurisdictions may be able to identify local subject matter experts.

Federal partners are essential to supporting coordination during a CBRNE incident. These programs provide Incident Command System structure, assist with wide-scale resource allocation, laboratory testing, monitoring and surveillance, and provide subject matter expertise on CBRNE considerations. These partners may include the Administration for Strategic Preparedness and Responses CHEMPACK program and Center for the Strategic National Stockpile, and CDC’s Laboratory Response Network. Other federal partners to collaborate with may include the Department of Homeland Security’s BioWatch program, the Department of Energy’s Radiation Assistance Program, FEMA’s Radiological Operations Support Specialist Program, and the National Guard Civil Support Team.

State and local response agencies are crucial for responding on the scene. These entities may include state and local health departments, law enforcement, first responders, and HazMat teams. These teams do a little bit of everything in aid to a local response — surveillance, medical triage, coordination, threat mitigation, and more. They understand the needs of their communities and play a crucial role in timely response.

Recovery from CBRNE incidents may have long-term considerations. Mental health is an important recovery consideration for incidents at mass gatherings. The stress and uncertainty surrounding a CBRNE incident can create or exacerbate mental health conditions. Both community members and emergency workers can be impacted.

Further, it will be important to conduct population monitoring to understand the long-term health impacts of the incident. This could include setting up registries to follow up with impacted individuals. It will be particularly important to monitor populations at higher risk of health impacts such as children or pregnant women. Emergency workers, including first responders and others, may also have more exposure to contamination or have mental health impacts from the response and will also need to be monitored.

The following resources are available to support public health preparedness, response, and recovery activities related to CBRNE incidents.

FAQ for Preparing for CBRNE Emergencies at Mass Gatherings

Webinars/Recorded Trainings

Other Resources/Toolkits