BackgroundExperimental studies have shown a decrease in driving performance at high temperatures. The epidemiological evidence for the relationship between heat and motor vehicle crashes is not consistent.ObjectivesWe estimated the impact of high ambient temperatures on the daily number of motor vehicle crashes and, in particular, on crashes involving driver performance factors (namely distractions, driver error, fatigue, or sleepiness).MethodsWe performed a time-series analysis linking daily counts of motor vehicle crashes and daily temperature or occurrence of heat waves while controlling for temporal trends. All motor vehicle crashes with victims that occurred during the warm period of the years 2000–2011 in Catalonia (Spain) were included. Temperature data were obtained from 66 weather stations covering the region. Poisson regression models adjusted for precipitation, day of the week, month, year, and holiday periods were fitted to quantify the associations.ResultsThe study included 118,489 motor vehicle crashes (an average of 64.1 per day). The estimated risk of crashes significantly increased by 2.9% [95% confidence interval (CI): 0.7%, 5.1%] during heat wave days, and this association was stronger (7.7%, 95% CI: 1.2%, 14.6%) when restricted to crashes with driver performance–associated factors. The estimated risk of crashes with driver performance factors significantly increased by 1.1% (95% CI: 0.1%, 2.1%) for each 1°C increase in maximum temperature.ConclusionsMotor vehicle crashes involving driver performance–associated factors were increased in association with heat waves and increasing temperature. These findings are relevant for designing preventive plans in a context of global warming.CitationBasagaña X, Escalera-Antezana JP, Dadvand P, Llatje Ò, Barrera-Gómez J, Cunillera J, Medina-Ramón M, Pérez K. 2015. High ambient temperatures and risk of motor vehicle crashes in Catalonia, Spain (2000–2011): a time-series analysis. Environ Health Perspect 123:1309–1316; http://dx.doi.org/10.1289/ehp.1409223

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Objective: We aim to analyse time evolution and seasonality of the outcomes of non-random alcohol concentration breath tests performed on drivers at sobriety checkpoints in Catalonia (Spain) from 2005 to 2012. Differences by gender are also explored.Methods: Time series analyses of the monthly prevalence of drunk drivers by gender. The sample consisted of all drivers tested at non-random sobriety checkpoints in Catalonia (Spain) from 2005 to 2012 (n=3,985,000). Our outcome variable was the monthly prevalence of drivers with a breath alcohol concentration at or above the legal limit. The driver's gender was also registered.Results: A decreasing trend in drunk-driving over time was found, the gender gap diminished after 2008 and disappeared in 2012. After adjusting for trend, the monthly coefficient presented the lowest value for males in January at 3.91% (p<0.001) and the highest in July at 4.72% (p<0.001) and September at 4.75% (p<0.001). The monthly coefficient was lowest for females in January at 3.05% (p<0.001) and highest in October at 4.12% (p <0.001). After seasonal the lowest coefficient is found in winter both for men and women. Conclusion:Seasonal patterns for male and female drivers testing positive at preventive nonrandom sobriety checkpoints indicate that the prevalence of drunk-driving peaks in spring for males and in autumn for females. We recommend that the authorities enforce campaigns that target male and female drinkers differently.

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