Hourly associations between ambient temperature and emergency ambulance calls in one central Chinese city: Call for an immediate emergency plan

[Display omitted] •Hourly temperature may increase ambulance calls with varying lag patterns.•Extreme hot has immediate effects on cardiovascular morbidity within 9 h.•Cold weather may be responsible for a substantial fraction of EACs burden. Most studies examining the short-term effects of temperature on health were based on the daily scale, few were at the hourly level. Revealing the relationship between unfavorable temperatures on an hourly basis and health is conducive to the development of more accurate extreme temperature early warning systems and reasonable dispatch of ambulances. Hourly data on temperature, air pollution (including PM2.5, O3, SO2 and NO2) and emergency ambulance calls (EACs) for all-cause, cardiovascular and respiratory diseases from January 16, 2014 to December 31, 2016 were obtained from Luoyang, China. A distributed lag non-linear model (DLNM) was used to assess the association between hourly temperature and ambulance calls after adjusting for potential confounding factors. The fractions of EACs attributable to non-optimum temperatures were also estimated. Hourly temperature was associated with increased ambulance calls with a varying lag pattern. Extreme hot temperature (>32.1 °C) was positively associated with all-cause, cardiovascular diseases at lag 0–30 h and lag 0–9 h, while no significant effects were found for respiratory morbidity. Extreme cold temperature (