Regardless of its nature, a disaster such as an earthquake, flooding, a transportation accident, a nuclear accident or an attack can engender a broad range of impacts on individual health and well-being and on the economy and the environment. The Civil Protection Act defines a disaster as “an event caused by a natural phenomenon, a technological failure or an accident, whether or not resulting from human intervention.” It causes serious harm to persons or substantial damage to property and exceeds institutional and organizational capacities to respond adequately in a timely manner (Québec government, 2018).

Against a backdrop of climate change, climate scenarios predict more frequent, more intense extreme weather events, sometimes characterized as disasters. Climate projections in Québec call, in particular, for longer heat waves and heavier precipitation leading to increased flooding, while other events, such as storm surges, could be more frequent or more pronounced (Ouranos, 2015).

There are different post-disaster intervention phases. The impact phase occurs during the disaster and mainly allows for immediate prevention. The phase immediately following a disaster should facilitate, as an example, a reduction in exposure and medical and psychological intervention. The post-impact phase several days or weeks after the disaster should allow for the continuation of intervention aimed at the vulnerable clientele but also to prepare for a return to normalcy. The recovery phase facilitates the restoration of the community’s social, economic, physical and environmental conditions and reduces disaster risks (Ministère de la Sécurité publique, 2008; Séguin et al., 2010).

The authorities usually properly document the immediate post-disaster impacts, especially as regards physical health and economic aspects. However, mental health impacts can be perceived as harder to document. Individuals who have experienced a disaster can develop mental health problems or such problems can be exacerbated. Certain impacts can be felt months and even sometimes years after the event. It is necessary and crucial that mental health resources and services be available to help a community recover from a disaster.

However, during the recovery phase, emergency services have withdrawn and it becomes necessary to evaluate in the longer term the service needs of the population affected. To ensure continued support for the community by offering sufficient, appropriate services, monitoring of the mental health impacts in the population affected becomes important. It should continue several years after an event in certain cases.

No clear definition determines when epidemiological surveillance can or should begin. Some authors specify that it begins when assistance is withdrawn, while others occasionally indicate two to four months after the disaster.

In Québec, epidemiological surveillance has existed for a long time but only a few epidemiological and surveillance studies have been conducted in the wake of major disasters, especially after flooding in the Saguenay in 1996 and the 1998 ice storm (Maltais et al., 2000; Bellerose, C. et al., 2000). The studies assessed events’ impacts on depressive, anxiety, post-traumatic stress disorder and distress symptoms. Since then, with the increase in certain climate-related disasters, interest has grown in carrying out surveillance of mental health impacts in respect of disasters of all scales. However, the means used to conduct such surveillance differ considerably from one study to the next and make comparisons difficult.

Moreover, certain Québec publications focus on post-disaster surveillance, mental health impacts or the tools to evaluate them (Appendix 1 summarizes the publications) (Bélanger et al., 2010; Boyer and Villa, 2011a; Boyer and Villa, 2011b; Bustinza et al., 2010a; Bustinza et al., 2010b; Tairou et al., 2011; Tairou et al., 2010b; Tairou, Bélanger and Gosselin, 2010a). The publications represent initial reflection on post-disaster surveillance in Québec and did not propose a comprehensive approach to guide such surveillance. Accordingly, the toolkit seeks to clarify the options available to conduct post-disaster surveillance in Québec.