Background: Qazvin province has suffered a lot of natural disasters (earthquakes) for a long time. so, the establishment of the first industrial city in Iran, has always been a source of concern. One of these problems is the possibility of chlorine gas leaking from the chlorination system of drinking water and treatment plant the existing ones are on the health of the inhabitants of this region.Material and method: This analytical study was carried out in Novorossiysk district of Alborz in December 2012. Initially, chlorine gas leakage scenarios from these facilities were simulated by ALOHA and WISER software, and then using the Emergency Level System, according to the CCPS Consultative Center's Chemical Process Safety Advice, the Emergency Response Program was presented. Results: ALOHA software, in comparison with WISER software, has more precision to identify and address the consequences of chlorine gas leakage hazards and according to the simulation of this software in the event of a leak from the well and water resources unit at 8240 m from the area and at night 7520 meters will be affected. Due to the speed of delivering results through the WISER software, this software can be used at times when the operating speed is considered (incident time).Conclusion: According to the CCPS model, the emergency conditions were classified at levels 3 and 4, therefore, the relevant crisis management agencies (Qazvin Crisis Management Committee, Alborz City Health Center, Red Crescent and Firefighting Authority) should provide training maneuvers At Alborz city level, and informing people of cities and industrial companies, many efforts have been made to reduce human and environmental damage in case of possible leakage.

Background: The purpose of this study was to evaluate and compare the performance of health, safety and environmental management of civil, traffic and urban services contractors in the 18th district of Tehran municipality in 2015-2016. Methods: This is an applied, longitudinal, descriptive-comparative study. The statistical population of this study was construction contractors, urban services and traffic in the municipality of district 18 of Tehran in the years 2015-2016. from 52 contractors, 18 construction contractors, 21 utilities contractors and 13 traffic contractors, respectively, were selected using census method. the research instrument consisted of periodic direct observation and completion of the HSE standard checklist by researchers. Data were analyzed using Kruskal-Wallis nonparametric test by SPSS software.Results: The HSE performance of all contractors (civil, utilities and traffic) was acceptable and the results of Kruskal-Wallis test showed that the HSE performance of contractors at the second visit of 2015 and the first visit of 2016 was significantly different in favor of civil contractors )p <0.01), but there was no significant difference between the first and third visits of 2015 and the second and third visits of 2016 (p> 0.05). visits in six periods indicate HSE Civil Contractors status increased from 100% unfavorable to 88.88% acceptable level and 11.11% good level, and in the case of civil service contractors who initially had 95.23% in an unfavorable situation and 4.76% in a favorable situation achieved 100% acceptable performance, and finally, the traffic contractors, who were 100% unfavorable, were upgraded to 100% acceptable. Conclusion: According to the findings of the study, it seems that the supervision of municipality inspectors on HSE performance of contractors can be effective in improving and strengthening the commitment to HSE requirements, therefore, it is suggested that periodical visits be made to the municipal contractors.