Bigdeli et al. BMC Public Health 2010, 10:406 http://www.biomedcentral.com/1471-2458/10/406 Table 5 Mean of the time intervals on city and interurban roads stratified by date, season and crash occurrence in the Urmia from 20 March 2005 to 20 March 2007 Date and season of injury City Mean(minute)* Interurban roads Weekday Response time Sunday Monday Tuesday Wednesday Thursday Friday Saturday Transport time Sunday Monday Tuesday Wednesday Thursday Friday Saturday Total pre-hospital time Sunday Monday Tuesday Wednesday Thursday Friday Saturday Season Response time Spring Summer Autumn Winter Transport time Spring Summer Autumn Winter Total pre-hospital time Spring Summer Autumn Winter *P values for all were < 0.05 5.1 5.0 4.7 4.5 5.6 4.9 4.8 5.7 6.9 6.0 6.6 6.5 5.3 6.1 25.6 25.4 23.9 24.5 26.5 23.8 24.2 5.0 4.7 5.0 5.3 6.5 5.5 5.9 7.0 25.1 23.4 25.2 26.5 8.9 10.8 11.3 11.1 10.5 11.2 9.9 13.8 16.3 17.6 18.9 15.6 23.7 18.6 40.2 49.3 48.2 47.9 44.1 52.1 45.8 9.6 10.5 11.4 11.8 17.2 19.3 17.8 20.1 44.5 44.9 48.1 56.2 Page 5 of 7 for city against interurban roads. The time intervals in this study can be important indicators for EMS perfor- mance evaluation in terms of resource planning and maybe also useful for assessing quality of patient care. Most of the time intervals were lower than similar stu- dies in Iran. The time interval between the RTI occur- rence and the onset of care at a designated trauma centre has been thought to be an important predictor of victim survival [17,18]. The average response interval in this study was lower than the findings from the capital city of Iran (7.1 vs. 14.9 minutes). The reasons for this shorter interval com- pared to Tehran, are mainly related to the infrastructure of the study area [16]. Urmia is a small city compared to Tehran, which is a very big city and usually suffers from traffic congestion that can result in delays in response time. Focusing on the location of the injury occurrence, the response interval for interurban roads was longer than in the city. Other studies have revealed that rapid responses are believed to have a major effect on the quality of care provided to trauma patients. If time to the trauma centre is a critical variable in the prediction of trauma outcome; then planners of emer- gency medical services on interurban road areas may be faced with the difficult task of providing services to vic- tims in this geographic location in terms of both pre- hospital care and hospital-based care, that is in line with line with previous recommendation in other studies [19,20]. The on-scene interval in this study was shorter than findings in Tehran, 7.4 vs. 18.0 minutes [21]. This time interval mainly can be affected by the skill of EMS team members as well as the involvement of lay people at the crash scene. In recent years many activities have been carried out in the study area [22] aimed at enhancing EMS personnel skills, which has resulted in their better performance during victim rescue. The other reason for such a short interval could also be related to the invol- vement of members of the public, initially as first responder and then their sense of urgency regarding vic- tim transportation before ambulance arrival. A study in Iran has indicated that, untrained laypeople feel that removing victims from the crash scene and taking them to hospital quickly is the best course of action for their survival [22]. This can result in over-rapid extrication of the casualties from the trapped vehicles before the arri- val of the ambulance crew. It is also important to note that, since motor vehicle crashes on interurban road areas often involve high speeds resulting in more serious