Bigdeli et al. BMC Public Health 2010, 10:406 http://www.biomedcentral.com/1471-2458/10/406 Page 3 of 7 Figure 1 Specific intervals and points in time for road traffic injury victims. Adapted with some modification from references [15,25]. relation to crash location, the t-test used again. The SPSS version 13.00 (SPSS Inc, Chicago, IL, USA) was used for data analysis. The study was approved by the Iranian National Ethics Committee at the Ministry of Health and Medical Education of Iran. Permission was also obtained from Urmia University of Medical Sciences. Results From all ambulance dispatches by EMS, 61.5% of RTIs victims were injured within the city compared to 38.5% cases that occurred on interurban roads. Among them, 27.7% deaths occurred in the city and the rest on inter- urban roads. Overall, 1.8% of all subjects died after EMS arrival at crash scene or en route to hospitals. Time intervals of EMS activities The mean values for the different time intervals of the activities are summarized in Table 1. The mean of the Table 1 Mean, median, mode, minimum and maximum of the time intervals of road traffic injury in the Urmia from 20 March 2005 to 20 March 2007 Time intervals Mean (SD) Activation 1.4 (0.59) interval Response interval 7.1 (5.6) On-scene interval 7.4 (5.2) Transport interval 10.5 (9.1) Total time 37.2 (17.2) intervals Median Mode Min Max 95% CI 1 6 6 7 32 1 2 5 5 26 1 8 1.39-1.46 2 45 6.87-7.49 3 25 7.06-7.64 3 57 9.96-10.95 14 114 36.25-38.18 response interval and on-scene interval were approxi- mately the same. The transport interval was slightly longer than response intervals. The variation of the total time interval was long with a minimum and maximum of 14-114 minutes, respectively. Table 2 presents time intervals by measurements of the central tendency in the EMS, stratified by city and interurban roads. The mean response time on interur- ban roads was longer than within the city (10.6 minutes vs. 5.0 minutes, p < 0.001). Moreover, the on-scene interval was longer on interurban roads compare to the city (9.2 vs. 6.1 minutes, p < 0.001). The transport time interval for both city and interurban roads was slightly longer than the response time interval. The mean of total pre-hospital time was almost twice for interurban roads compared to the city (p < 0.001). As Table 3 shows, there was no significant association between activation time for RTIs on city and interurban roads. However, there was significant association for response time in the city compared to on interurban roads (p < 0.001). Focusing on total pre-hospital time intervals, around eight out of ten victims in the city were transported in less than 30 minutes, while for vic- tims on interurban roads; one out of four had been transported in less than 30 minutes. Response times varied significantly between the city compared to interurban roads (P < 0.001). Close to 90% of response time within the city were less than 8.0 min- utes, compared to 45.7% on interurban roads. There was significant association between transportation interval time and crash site (P < 0.001). In general, 99.5% of vic- tims of RTIs in the city had arrived at hospital within