Environmental Research 216 (2023) 114640 Available online 26 October 2022 0013-9351/© 2022 Elsevier Inc. All rights reserved. Heat and air quality related cause-based elderly mortalities and emergency visits Mohamed Dardir a, c, * , Jeffrey Wilson a , Umberto Berardi b a School of Environment, Enterprise, and Development, University of Waterloo, Waterloo, ON, N2L 3G1, Canada b Department of Architectural Science, Toronto Metropolitan University, Toronto, ON, M5B 2K3, Canada c Department of Architectural Engineering, Ain Shams University, Cairo, Egypt A R T I C L E INFO Keywords: Air quality Heat wave Extreme heat Mortality Emergency visits Clustering analysis Greater toronto area Greenbelt ABSTRACT The combined effects of heat events and poor air quality conditions can severely affect population health. A novel correlational method was developed to assess the impact of the short-term variations of environmental variables (air pollutants and ambient conditions) on community health responses (mortalities and emergency department visits). A multi-dimensional clustering approach was proposed by combining hierarchical and k-means clustering to promote fexibility and robustness to improve the correlation procedure. The study focused on the health records of the elderly population and people diagnosed with cardiorespiratory causes. The study investigated multiple health records on different levels of investigation: total, elderly, cause-based, and elderly cause-based records. The developed method was validated by investigating the short-term impact of ambient air tempera- ture, relative humidity, ground-level ozone, and fne particulate matter on the health records during hot and warm seasons in the municipalities of Mississauga and Brampton, Peel Region, Ontario, Canada for 15 years. The analysis confrmed the association between moderate levels of environmental variables and increased short-term daily total deaths and emergency department visits, while the elderly sector showed higher vulnerability to environmental changes. Furthermore, the association with extreme heat conditions and poor air quality levels was affrmed with cause-based mortalities and emergency visits; the correlation was strongest with elderly cause- based health records. Findings confrm that cardiorespiratory patients, especially elderly people, were at the greatest risk of poor environmental conditions. 1. Introduction The effects of climate change, heat events, and poor air quality lead to excessive heat stress and living conditions for urban dwellers and increase environmental-based morbidity and mortality (Azhar et al., 2014; Bae et al., 2020; Tsekeri et al., 2020). Extreme heat events are associated with high ambient temperature and humidity levels. The most severe impacts of heat waves result from multi-day heat stress, warm nights, and increased relative humidity (RH). The projected in- crease in heat wave intensity in the future is expected to cause severe health impacts (Fischer and Sch¨ ar, 2010; Jandaghian and Berardi, 2020a, 2020b). The characteristics of heat wave events are defned regionally according to the local climatic conditions. According to Health Canada (2017) for Southern Ontario (Greater Toronto), a heat wave occurs when the daytime maximum temperature exceeds 31 ◦ C and the night-time minimum temperature exceeds 20 ◦ C for at least 2 consecutive days. Health Canada also reports a heat wave if the local temperature-humidity index (Humidex) in the above-mentioned region reaches 40 or more for at least 2 consecutive days. Meanwhile, urban heat island effects combined with climate change issues are increasing the concerns in countries like Canada, traditionally considered less vulnerable to heat waves (Berardi et al., 2020; Berardi and Wang, 2016; Wang et al., 2015). Signifcant correlations were reported between heat-related mortal- ities and extreme heat events, especially for elderly people (Azhar et al., 2014; Gronlund et al., 2014; Rainham and Smoyer-Tomic, 2003; Tsekeri et al., 2020), with a signifcant association for cardiorespiratory-related fatalities (Baccini et al., 2008; Basu et al., 2005; D’Ippoliti et al., 2010; Paravantis et al., 2017). Investigations in North America reported strong causality for daily mortality due to exposure to excessive heat (Berko et al., 2014; Harlan et al., 2014). Also, several studies reported the short-term impact of heat exposure on health records (Basu et al., 2005; * Corresponding author. School of Environment, Enterprise, and Development, University of Waterloo, Waterloo, ON, N2L 3G1, Canada. E-mail address: mdardir@uwaterloo.ca (M. Dardir). Contents lists available at ScienceDirect Environmental Research journal homepage: www.elsevier.com/locate/envres https://doi.org/10.1016/j.envres.2022.114640 Received 29 January 2022; Received in revised form 15 September 2022; Accepted 20 October 2022