Introduction Natural hazards resulting in disasters are increasing globally, impacting communities and disrupting industries. In addition to planning for these natural hazard disasters, emergency departments (EDs) should prepare for chemical, biological, radiological, and nuclear (CBRN) incidents that result in surges of patient presentations. Chemical, biological, radiological, and nuclear incidents differ in preparedness to natural hazards, requiring an understanding of patient management and health system-related challenges.

Methods This scoping review used the Arksey and O’Malley five-step framework. Manuscripts were retrieved from four databases and search engines using keywords relating to impacts on the ED from real world CBRN event(s). Analysis focused on the characteristics of CBRN event, ED impact, and lessons learnt against four surge capacity domains that including staff, stuff, space, and systems.

Results A total of 44 paper were included in this review. Most of the incidents were chemical in nature (n = 36/44, 81.8 %). The majority of CBRN incidents were accidental (n = 34/44, 77.3 %). Between 1 and 1470 people (Mdn=56, IQR: 18–228) presented to an ED from each event. Most patients were discharged from the ED, but this was variably reported. Some key lessons related to secondary exposure to ED staff, repurposing spaces, and coordination of CBRN incidents.

Conclusion With the increasing number of CBRN incidents, strategies to strengthen EDs and limit the impact from a surge in patient presentations are paramount. An understanding of local CBRN risk to inform a top-hazards approach to CBRN preparedness, and the implementation of pre-emptive CBRN clinical pathways is recommended. Additionally, strategies should be implemented to protect staff from the risk of secondary exposure to a CBRN event. These strategies may include adequate education, training, and personal protective equipment for staff.