Mass gatherings involving hazardous materials (HAZMAT) poses unique challenges to the operations of any emergency department. A screening station is essential for risk stratification and identification of HAZMAT casualties. Existing patients and relatives in the emergency department must be restricted and controlled. Prompt segregation and decontamination of casualties is crucial in a HAZMAT incident. Identification of such a facility with planning of inflow and outflow routes must not be undermined. Crowd control should be performed by securing all entrances and exits, minimizing cross-contamination The topography of the emergency department must be examined with the objectives of minimizing acquaintance and cross-contagion in mind. Directional leadership is crucial during chaotic situations. Clarity of thought and decisiveness is critical. Good communication channels must be established with internal and external agencies in all phases of emergency department response. Apart from the acute response mechanism, training is an important factor in enhancing staff preparedness. Regular continuity of education is essential to keep staff up-to-date with the latest procedures and legislation. Drills and audits are useful for assessing staff competency levels. Familiarity and easy accessibility to overall response plans and detailed individual action cards also are important. The availability and adequacy of operationally ready equipments and consumables must not be underestimated. All equipment and consumables must be easily accessible and clearly labeled. Bimonthly audits are recommended to ensure defect-free equipment and validity of consumables. In conclusion, regardless of these difficulties, emergency departments continue to be the main provider of care to contaminated individuals. Thus, it is imperative that all emergency departments in Singapore be vigilant during peace time.