Delineation of Spatial Variability in the Temperature–Mortality Relationship on Extremely Hot Days in Greater Vancouver, Canada

Abstract

Background:Climate change has increased the frequency and intensity of extremely hot weather. The health risks associated with extemely hot weather are not uniform across affected areas owing to variability in heat exposure and social vulnerability, but these differences are challenging to map with precision.Objectives:We developed a spatially and temporally stratified case-crossover approach for delineation of areas with higher and lower risks of mortality on extremely hot days and applied this approach in greater Vancouver, Canada.Methods:Records of all deaths with an extremely hot day as a case day or a control day were extracted from an administrative vital statistics database spanning the years of 1998–2014. Three heat exposure and 11 social vulnerability variables were assigned at the residential location of each decedent. Conditional logistic regression was used to estimate the odds ratio for a 1°C increase in daily mean temperature at a fixed site with an interaction term for decedents living above and below different values of the spatial variables.Results:The heat exposure and social vulnerability variables with the strongest spatially stratified results were the apparent temperature and the labor nonparticipation rate, respectively. Areas at higher risk had values ≥ 34.4°C for the maximum apparent temperature and ≥ 60% of the population neither employed nor looking for work. These variables were combined in a composite index to quantify their interaction and to enhance visualization of high-risk areas.Conclusions:Our methods provide a data-driven framework for spatial delineation of the temperature-–mortality relationship by heat exposure and social vulnerability. The results can be used to map and target the most vulnerable areas for public health intervention.Citation:Ho HC, Knudby A, Walker BB, Henderson SB. 2017. Delineation of spatial variability in the temperature–mortality relationship on extremely hot days in greater Vancouver, Canada. Environ Health Perspect 125:66–75; http://dx.doi.org/10.1289/EHP224

Spatiotemporal analysis of regional socio-economic vulnerability change associated with heat risks in Canada

“…Local calibration is potentially important because the relationship between heat exposure, social vulnerability and mortality is highly variable among different cities (O’Neill et al, 2003; O’Neill et al, 2005). Such calibration can be performed with local historical weather and morbidity/mortality datasets (Bell et al, 2008; Chuang et al, 2016; Ho et al, 2017; Hu et al, 2017; Rosenthal et al, 2014; Smargiasssi et al, 2009). Furthermore, given the importance of immigration for the population growth seen from 2006 to 2011, it might be useful to include the immigrant population as an additional variable and assess its contribution to heat vulnerability in Canada.…”

“…Low education population was defined by “people with fairly low education level (without a diploma nor a degree)”, and people living alone was defined by “number of single-person household”, in which these factors related to less knowledge and awareness for extreme heat mitigation, and associated with potential social isolation with less health care during extreme weather events. >ow income population were “people with household income less than $20,000, and unemployed was represented by “unemployment rate”, in which those were factors associated with the Vancouver Area Neighbourhood Deprivation Index (VANDIX) and VANDIX was found to be related to heat mortality in Canada (Ho et al, 2017). …”

“…It is important to combine both spatial and temporal trends to investigate how changing populations in communities may influence heat vulnerability in the future (Sheridan & Dixon, 2016), and ultimately combine the resulting information with climate projections (also stated in Health Canada guideline for extreme heat and health vulnerability assessment) to facilitate extreme heat adaptation (Goldberg et al, 2007; Gosling et al, 2009; Huang et al, 2011; Jackson et al, 2010; Jeong et al, 2016). While ambient temperature largely determines the heat exposure of a population, vulnerability defines how that population is affected by the exposure, which during extreme heat events may lead to substantial excess mortality (Ho et al, 2017; Toloo et al, 2014). The relationship between heat exposure, vulnerability and risk is complicated by both short- and long-term acclimatization, as evidenced by latitudinal gradients in the temperature-mortality relationship (Henderson et al 2013, Anderson and Bell 2009), and also by societal responses to heat such as heat emergency warning systems (Kalkstein & Sheridan, 2007; Toloo et al, 2013; Toloo et al, 2014; Tong et al, 2016).…”

Spatial variability of excess mortality during prolonged dust events in a high-density city: a time-stratified spatial regression approach

“…However, there has been no study to investigate the spatial variability of mortality risk during a prolonged dust event. In contrast to a lack of research on this issue, extensive environmental health studies on extreme weather and pollution have pointed out the necessity of predicting spatial variability of mortality and morbidity [2, 20, 23, 27, 29], for the purpose of measuring community vulnerability and public health planning. Estimating community vulnerability is particularly important to a high-density city, as the urban morphology of a high-density city influences air pollutant dispersion [58], resulting in extreme conditions with severe health risk, in particular at the district level.…”

Assessing Urban Risk to Extreme Heat in China

“…The degree of hazard depends on the physical attributes of the disaster event [40]. In this paper, we attempted to examine the spatial-temporal changes in physical attributes of extreme heat as a hazard factor.…”