Indoor temperature and health: a global systematic review

• Published in: Public health (London) 2020-02, Vol.179, p.9-17
• Main Authors: Tham, S., Thompson, R., Landeg, O., Murray, K.A., Waite, T.
• Format: Article
• Language: English
• Subjects: Absorption; At risk populations; Blood pressure; Child care; Climate Change; Clinical outcomes; Cognition; Cohort analysis; Dementia; Dementia disorders; Design; Diabetes; Diabetes mellitus; Diabetics; Disease management; Disease transmission; Dosage; English language; Environmental management; Exposure; Female; Functional impairment; Global health; Glucose; Health Status; Heat; Heterogeneity; High temperature; Hot Temperature - adverse effects; Humans; Indoor; Indoor environments; Infants; Influenza; Insulin; Literature reviews; Mental disorders; Mental Health; Overheating; Population studies; Pregnancy; Psychological distress; Public Health; Risk groups; Risk management; Schizophrenia; Side effects; Sustainability; Systematic review; Temperature
• ISSN: 0033-3506; 1476-5616
• DOI: 10.1016/j.puhe.2019.09.005

The objective of this study was to identify and appraise evidence on the direct and indirect impacts of high indoor temperatures on health; the indoor temperature threshold at which the identified health impacts are observed; and to summarise the evidence for establishing a maximum indoor temperature threshold for health. This is a systematic literature review and narrative synthesis. A review of the published literature using MEDLINE, EMBASE, Global Health, PsycINFO, Maternity and Infant Care, Cochrane Library, CINAHL and GreenFILE databases was conducted. The search criteria were kept broad to capture evidence from all countries and contexts; no date or study design limits were applied, except English language limits. We included studies that specifically measured indoor temperature and examined its effect on physical or mental health outcomes. Evidence was graded using the National Institutes of Health framework. Twenty-two articles were included in the review, including 11 observational, seven cross-sectional and three longitudinal cohort studies and one prospective case–control study. Eight main health effects were described: respiratory, blood pressure, core temperature, blood glucose, mental health and cognition, heat-health symptoms, physical functioning and influenza transmission. Five studies found respiratory symptoms worsened in warm indoor environments, with one reporting indoor temperatures higher than 26 °C, which was associated with increased respiratory distress calls being made to paramedics (odds ratio = 1.63, P = 0.056). Core symptoms of schizophrenia and dementia were found to be significantly exacerbated by indoor heat (the latter above a 26 °C cumulative exposure threshold). The absorption of insulin doses in people with type one diabetes was also significantly accelerated in hot indoor environments. Only five studies reported the temperatures at which health outcomes worsened, with thresholds ranging between 26 °C and 32 °C. However, owing to insufficient data and the heterogeneity of the included studies (design, population, setting, exposure measures, outcomes and location), meta-analysis and an upper threshold determination was not feasible. High indoor temperatures affect aspects of human health, with the strongest evidence for respiratory health, diabetes management and core schizophrenia and dementia symptoms. Exacerbation of symptoms in warm indoor environments has clinical relevance to at-risk groups and those caring for the