Dynamics thresholds for heat-health watch and warning system with extended season

Abstract

BACKGROUND AND AIM: A significant number of heat waves with very severe impacts have been observed over the past three decades. The multiplication of the latter during the last decades has incited some countries to elaborate heat-health watch and warning systems (HHWWS). However, these HHWWS cover the hottest months of the year with a unique threshold for the whole summer season. According to some studies, the summers are expected to be longer and hotter in a future climate, with periods of heat waves earlier and later in the season. Besides, the heat effects tend to be more severe when the human body is not acclimatized to hot temperatures. To adapt the system to potential heat waves outside the hot season and consider the meteorological variability within the season, this study proposes a HHWWS with an extended season and evolving thresholds per month. METHODS: For this, historical health and weather data over the years of Greater Montreal area (Canada) are considered. Splines and distributed lag non-linear model (DLNM) were also used in our approach to the implementation of the system. RESULTS:The resulting HHWWS provide thresholds for a couple of maximum and minimum temperature (in °C) that range from (23 and 12) in April, to (32 and 21) in July and back to (25 and 13) in October. CONCLUSIONS:The proposed system is more flexible and adapted over an extended season and with monthly evolving thresholds. KEYWORDS: Warning systems,Temperature extremes, Environmental epidemiology, climate, thresholds, mortality.