What weather variables are important in predicting heat-related mortality? A new application of statistical learning methods
Open accessAbstract
Hot weather increases risk of mortality. Previous studies used different sets of weather variables to characterize heat stress, resulting in variation in heat-mortality associations depending on the metric used. We employed a statistical learning method - random forests - to examine which of the various weather variables had the greatest impact on heat-related mortality. We compiled a summertime daily weather and mortality counts dataset from four U.S. cities (Chicago, IL; Detroit, MI; Philadelphia, PA; and Phoenix, AZ) from 1998 to 2006. A variety of weather variables were ranked in predicting deviation from typical daily all-cause and cause-specific death counts. Ranks of weather variables varied with city and health outcome. Apparent temperature appeared to be the most important predictor of heat-related mortality for all-cause mortality. Absolute humidity was, on average, most frequently selected as one of the top variables for all-cause mortality and seven cause-specific mortality categories. Our analysis affirms that apparent temperature is a reasonable variable for activating heat alerts and warnings, which are commonly based on predictions of total mortality in next few days. Additionally, absolute humidity should be included in future heat-health studies. Finally, random forests can be used to guide the choice of weather variables in heat epidemiology studies.
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Workers felt more uncomfortable in a hot and humid environment than in a hot and dry environment, with heat stress further exacerbated by heavy workload, personal protective equipment (PPE), among other factors.
“Workers felt more uncomfortable in a hot and humid environment than in a hot and dry environment, with heat stress further exacerbated by heavy workload, personal protective equipment (PPE), among other factors [9].”
From Assessing Heat Stress and Health among Construction Workers in a Changing Climate: A Review (2018) · cites this paper as [9]
The Discussion (page unavailable) says absolute humidity may reflect physiologically stressful heat exposure. It does not compare workers’ discomfort in hot-humid and hot-dry conditions or discuss heavy workload or PPE as factors that exacerbate heat stress. (LLM, conf=0.80)
Experimental — accuracy not yet measuredSeveral studies in environmental epidemiology concluded that the 'best measure to heat stress varied with populations and regions'.
“Several studies in environmental epidemiology that have examined the associations between heat and mortality concluded that the ‘best measure to heat stress varied with populations and regions’ [9].”
From Assessing Heat Stress and Health among Construction Workers in a Changing Climate: A Review (2018) · cites this paper as [9]
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Humidity: a review and primer on atmospheric moisture and human health
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Impacts of heat waves and corresponding measures: a review
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Assessing Heat Stress and Health among Construction Workers in a Changing Climate: A Review
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“Workers felt more uncomfortable in a hot and humid environment than in a hot and dry environment, with heat stress further exacerbated by heavy workload, personal protective equipment (PPE), among other factors [9].”
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- Authors
- Zhang, K., Li, Y., Schwartz, J. D., & O׳Neill, M. S.
- Affiliations
- The University of Texas Health Science Center at Houston (US)
- University of Michigan (US)
- Harvard University (US)
- Corresponding author
- Zhang, Kai
- Venue
- Environmental Research
- Publisher
- Elsevier BV
- Published
- 2014-07
- Volume
- 132
- Pages
- 350-359
- ISSN
- 0013-9351 (ISSN-L)
- PMC
- PMC4091921
- OpenAlex
- W2050948329
- Cited by
- 152
- References
- 1
- Citations by year
- 2026: 11 · 2025: 21 · 2024: 18 · 2023: 10 · 2022: 20 · 2021: 14 · 2020: 10 · 2019: 6 · 2018: 10 · 2017: 8 · 2016: 12 · 2015: 9 · 2014: 3
- FWCI
- 7.01
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Locations
- Environmental Research (publishedVersion)
- PubMed (publishedVersion)
- PubMed Central (acceptedVersion)
- Funders
- U.S. Environmental Protection Agency
- Star Scientific Foundation (R832752010, R18 EH 000348)
- National Institute of Environmental Health Sciences (R01 ES-016932, R21 ES-020695)
- University of Michigan
- Topics
- Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Climate Change and Health Impacts
- Health Sciences › Medicine › Physiology › Thermoregulation and physiological responses
- Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Air Quality and Health Impacts
- Keywords
- heat-related mortality, heat stress, meteorological parameters, apparent temperature, absolute humidity, random forest, heat alerts, cause-specific mortality, all-cause mortality, urban heat
- MeSH terms
- Chicago, Cities, Hot Temperature, Humans, Mortality, Statistics as Topic, Philadelphia
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