Dan Wang1, Kevin Ka-Lun Lau2, Chao Ren3, William Bernard Iii Goggins4, Yuan Shi5, Hung Chak Ho6, Tsz-Cheung Lee7, Lap-Shun Lee8, Jean Woo9, Edward Ng10. 1. Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China; Jockey Club Institute of Ageing, The Chinese University of Hong Kong, Hong Kong, China. 2. Jockey Club Institute of Ageing, The Chinese University of Hong Kong, Hong Kong, China; Institute of Future Cities, The Chinese University of Hong Kong, Hong Kong, China. Electronic address: kevinlau@cuhk.edu.hk. 3. Institute of Future Cities, The Chinese University of Hong Kong, Hong Kong, China; Faculty of Architecture, The University of Hong Kong, Hong Kong, China. Electronic address: renchao@hku.hk. 4. Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China. Electronic address: wgoggins@cuhk.edu.hk. 5. School of Architecture, The Chinese University of Hong Kong, Hong Kong, China. 6. Department of Urban Planning and Design, The University of Hong Kong, Hong Kong, China. Electronic address: hcho21@hku.hk. 7. Hong Kong Observatory, Hong Kong, China. Electronic address: tclee@hko.gov.hk. 8. Hong Kong Observatory, Hong Kong, China. Electronic address: lslee@hko.gov.hk. 9. Jockey Club Institute of Ageing, The Chinese University of Hong Kong, Hong Kong, China; Department of Medicine & Therapeutics, The Chinese University of Hong Kong, Hong Kong, China. Electronic address: jeanwoowong@cuhk.edu.hk. 10. Institute of Future Cities, The Chinese University of Hong Kong, Hong Kong, China; School of Architecture, The Chinese University of Hong Kong, Hong Kong, China. Electronic address: edwardng@cuhk.edu.hk.
Abstract
BACKGROUND: The impact of heatwaves on public health has led to an urgent need to describe extremely hot weather events (EHWEs) and evaluate their health impacts. METHODS: In Hong Kong, a very hot day (VHD) can be defined when the daily maximum temperature ≥ 33 °C, and a hot night (HN) can be identified if the daily minimum temperature ≥ 28 °C. Three lengths of time, nine combinations of VHD and HN, and four categories of occurrence intervals between two EHWEs were considered over 2006-2015. The daily relative risk (RR) of all-cause mortality was estimated using Poisson generalized additive regression models, controlling for both short-term and long-term trends in temperature as well as four air pollutants. Lagged effects of the representative EHWEs were further examined for their association with mortality. Subgroup analysis was conducted for different sex and age groups. RESULTS: Significant associations with raised mortality risks were observed for a single HN, while stronger associations with mortality were observed as significant for five or more consecutive VHDs/HNs. More HNs between the consecutive VHDs also significantly amplified the impact on mortality, with the strongest association observed for EHWEs characterized as 2D3N, and the effect significantly lagged for five days. Therefore, with identifiable health impacts, three thresholds (5VHDs, 5HNs, & 2D3N) were determined to be representative of identical types of EHWEs in Hong Kong. Furthermore, by taking 2 (3) consecutive VHDs (HNs) as one daytime (nighttime) EHWE event, those occurring consecutively without non-hot days (nights) in between were found to be significantly associated with excess mortality risks. Moreover, females and older adults were determined to be relatively more vulnerable to all defined EHWEs. CONCLUSIONS: Among all the observed significant heat-mortality associations in highly urbanized cities, EHWEs that occurred during the nighttime, with extended length, consecutively without any break in between, or in the pattern of 2D3N might require the meteorological administration, healthcare providers, and urban planners to work interactively.
BACKGROUND: The impact of heatwaves on public health has led to an urgent need to describe extremely hot weather events (EHWEs) and evaluate their health impacts. METHODS: In Hong Kong, a very hot day (VHD) can be defined when the daily maximum temperature ≥ 33 °C, and a hot night (HN) can be identified if the daily minimum temperature ≥ 28 °C. Three lengths of time, nine combinations of VHD and HN, and four categories of occurrence intervals between two EHWEs were considered over 2006-2015. The daily relative risk (RR) of all-cause mortality was estimated using Poisson generalized additive regression models, controlling for both short-term and long-term trends in temperature as well as four air pollutants. Lagged effects of the representative EHWEs were further examined for their association with mortality. Subgroup analysis was conducted for different sex and age groups. RESULTS: Significant associations with raised mortality risks were observed for a single HN, while stronger associations with mortality were observed as significant for five or more consecutive VHDs/HNs. More HNs between the consecutive VHDs also significantly amplified the impact on mortality, with the strongest association observed for EHWEs characterized as 2D3N, and the effect significantly lagged for five days. Therefore, with identifiable health impacts, three thresholds (5VHDs, 5HNs, & 2D3N) were determined to be representative of identical types of EHWEs in Hong Kong. Furthermore, by taking 2 (3) consecutive VHDs (HNs) as one daytime (nighttime) EHWE event, those occurring consecutively without non-hot days (nights) in between were found to be significantly associated with excess mortality risks. Moreover, females and older adults were determined to be relatively more vulnerable to all defined EHWEs. CONCLUSIONS: Among all the observed significant heat-mortality associations in highly urbanized cities, EHWEs that occurred during the nighttime, with extended length, consecutively without any break in between, or in the pattern of 2D3N might require the meteorological administration, healthcare providers, and urban planners to work interactively.
Authors: Alexander Baklanov; Beatriz Cárdenas; Tsz-Cheung Lee; Sylvie Leroyer; Valery Masson; Luisa T Molina; Tanya Müller; Chao Ren; Felix R Vogel; James A Voogt Journal: Urban Clim Date: 2020-04-01
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Authors: Raphael Romano Bruno; Bernhard Wernly; Maryna Masyuk; Johanna M Muessig; Rene Schiffner; Laura Bäz; Christian Schulze; Marcus Franz; Malte Kelm; Christian Jung Journal: Wien Med Wochenschr Date: 2021-03-18