對於災難的風險分析，有助於促進災難管理的優先考量、政策制定與預算支持。由於災難通常係指人類資源的嚴重供需失調，瞭解與未來環境危害程度及耐受能力主要相關因素，極為重要。然而，實證災難醫學研究顯示，人們對於災難醫學常有認知上的差距。因此，在災難醫學中，一直存在著許多迷思與謬誤。首先，我們應該區分有關危害、事件、健康傷害及健康災難的精確定義；亦應瞭解當今世上災難每天發生。百分之九十的災難是與水災有關。評估健康災難的最好指標，是需要健康照護的存活者數目，而非死亡總數。災難發生時，大多數的災民並不會驚慌失措，而且大多數的存活者是因自救或鄰近旁人的救助。大多數的災民只要自己能行動，不會藉助緊急救護系統，而會逕行至醫院就診；甚至遭受污染的災民亦然。災民在各醫院分佈情形極不平均，有些醫院過度擁擠，且常為輕症病患所擠滿。災民通常在災後幾分鐘就抵達醫院。極少數的災民死亡，發生在急診；大多數的災民在急診治療後即可出院。外來的災難醫療援助，能提供災民的緊急醫療有限。大多數的受難者，並沒有黃金72 小時的救援時間。災區原有的流行病才有蔓延可能，但絕不會無中生有；因此受難者屍體並不會帶來瘟疫。危急事件壓力會報並不會減輕創傷後壓力症候群的發生。

Risk stratification during a disaster drives the priorities and adequacies of disaster management, policies, and government funding. Since disasters always produce a severe imbalance between supply and demand in human communities, it is essential for disaster risk assessment to understand the major factors involved in future hazards and vulnerabilities. However, evidencebased disaster medicine studies reveal a large gap between perceptions of what occurs and what actually occurs in disasters. There are thus some common myths and fallacies regarding disaster medicine. First, I distinguish among hazards, events, health damage, and health disasters, when a disaster actually occurs somewhere in the world. Ninety percent of disasters are hydrometrological. The best measure of the magnitude of a health disaster should be the number of survivors requiring health services instead of the number of deceased.Most survivors do not panic, and they usually rescue themselves or are rescued by bystanders. Most victims, if not incapacitated, bypass emergency medical services (EMSs) to reach hospitals, as is also true for contamination victims. Victims are usually non-uniformly distributed, i.e., some hospitals receive a disproportionate share of victims. Victims may begin arriving at hospitals within minutes after a sudden-onset event, and those with minor injuries tend to reach hospitals first. Relatively few victims die in emergency departments (EDs) and some are successfully resuscitated.Most victims are treated and released from EDs. Outside medical assistance such as disaster management assistance teams (DMATs) normally provides little emergency medical care, and search teams rescue few survivors. Most victims entrapped in a sudden-onset emergency event do not have the often-quoted golden period of 72 h for rescue. Only pathogens which are already endemic in a community pose a risk of infectious diseases after a disaster, so dead bodies pose a negligible risk of plague infection, for example, after a disaster. Critical incident stress debriefing does not prevent post-traumatic stress disorder.