Changing patterns of the temperature–mortality association by time and location in the US, and implications for climate change. (August 2015)

• Record Type: Journal Article
• Authors: Nordio, Francesco; Zanobetti, Antonella; Colicino, Elena; Kloog, Itai; Schwartz, Joel
• Is Part Of: Environment international. Volume 81(2015:Aug.)
• Page Start: 80
• Page End: 86
• Publication Date: 2015-08
• Subjects: Climate change -- Health effects -- Temperature -- Meta-smoothing; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2015.04.009
• Languages: English
• ISSNs: 0160-4120

Abstract

Abstract: The shape of the non-linear relationship between temperature and mortality varies among cities with different climatic conditions. There has been little examination of how these curves change over space and time. We evaluated the short-term effects of hot and cold temperatures on daily mortality over six 7-year periods in 211 US cities, comprising over 42 million deaths. Cluster analysis was used to group the cities according to similar temperatures and relative humidity. Temperature–mortality functions were calculated using B-splines to model the heat effect (lag 0) and the cold effect on mortality (moving average lags 1–5). The functions were then combined through meta-smoothing and subsequently analyzed by meta-regression. We identified eight clusters. At lag 0, Cluster 5 (West Coast) had a RR of 1.14 (95% CI: 1.11, 1.17) for temperatures of 27 °C vs 15.6 °C, and Cluster 6 (Gulf Coast) has a RR of 1.04 (95% CI: 1.03, 1.05), suggesting that people are acclimated to their respective climates. Controlling for cluster effect in the multivariate-meta regression we found that across the US, the excess mortality from a 24-h temperature of 27 °C decreased over time from 10.6% to 0.9%. We found that the overall risk due to the heat effect is significantly affected by summer temperature mean and air condition usage, which could be a potential predictor in building climate-change scenarios. Highlights: We studied 42 million deaths in 211 U.S. cities from the 1960's to recent years. We showed that the effect of hot days is diminished by increasing summer mean temperature within city. Similarly, the effect of cold days is increased by increasing winter mean temperature. A modest protective effect of air conditioning was found controlling for the above. Risk assessments of future temperature changes need to take these adaptive responses into account.