Health Scope. 2016 May; 5(2):e32540. doi: 10.17795/jhealthscope-32540 Published online 2016 January 1. Research Article Dispersion Modeling of Nitrogen Dioxide in Ambient Air of Ahvaz City Mohammad Javad Mohammadi, 1,2,* Gholamreza Goudarzi, 2,3 Sahar Geravandi, 4,5 Ahmad Reza Yari, 6 Bashir Ghalani, 7 Saeed Shirali, 8 Elahe Zallaghi, 9 and Mehdi Esmaili 10 1 Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran 2 Department of Environmental Health Engineering, School of Public Health, Clinical Research Development Center, Razi Teaching Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran 3 Environmental Technologies Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran 4 Department of Nursing, Islamic Azad University, Tehran Medical Sciences Branch, Tehran, IR Iran 5 Clinical Research Development Center, Razi Teaching Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran 6 Department of Environmental Health, School of Health, Research Center for Environmental Pollutants, Qom University of Medical Sciences, Qom, IR Iran 7 Department of Industrial Engineering, Islamic Azad University, Ahvaz, IR Iran 8 Department of Laboratory Sciences, School of Paramedical Sciences, Hyperlipidemia Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran 9 Applied Science Training Center, Ahvaz Municipality University, Ahvaz, IR Iran 10 Water Science Faculty, Shahid Chamran University of Ahvaz, Ahvaz, IR Iran *Corresponding author: Mohammad Javad Mohammadi, Department of Environmental Health Engineering, School of Public Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran. Tel: +98-9355439707, Fax: +98-6113361544, E-mail: javad.sam200@gmail.com; Mohamadi.m@ajums.ac.ir Received 2015 August 18; Revised 2015 October 25; Accepted 2015 November 4. Abstract Background: Air emission modeling is used to study how pollutants are spread in the environment and to forecast their emissions rate in different climatic conditions in the study area. Today, air pollution threatens human public health and the environment, and Ahvaz is considered one of the main centers of air pollution in Iran. Objectives: This aim of this study was to evaluate the nitrogen dioxide distribution in Ahvaz by using the software program Screen 3. Materials and Methods: This analytical study was conducted in 2013 in Ahvaz. Data collections were performed by the Ahvaz Department of Environment. After processing the data received (averaging instruction set, coding), the file was converted to an input file for the software program Screen 3. In the next phase, study of the distribution and release of nitrogen dioxide during the year 2013 was modeled using the Screen 3 software. Results: Based on the results of this study, the highest and the lowest nitrogen dioxide concentration were in the Bureau of Meteorology and Head office of ADoE stations, respectively. The maximum concentration of NO 2 , at a height of 45 m, was 20 μg/m 3 .According to the findings of the modeling, examination of the combustion process was observed, and this was caused by the amount of nitrogen dioxide emitted by flue outlets, which was affected by temperature and pressure, fuel flow rates and inlet air temperature. Also, results showed that in most cases emission of air pollutants was towards the southwest. Conclusions: Results of this study showed that the Screen3 software is one of the popular models for estimating the distribution of air pollutants. Nitrogen dioxide emissions are highly regulated in most industrialized regions. Decreased emissions from fuel combustion, the use of scrubbers and filters that absorb pollution can be very useful for reduction and control of nitrogen dioxide emissions. Keywords: Air Pollutants, Nitrogen Dioxide, Software, Environment Copyright © 2016, Health Promotion Research Center. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommer- cial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited. 1. Background The increasing development of urban areas, increasing energy consumption and rapid growth of the economy are some of the most important factors that threaten health and the environment (1-5). Nowadays, inatten- tion to environmental and air pollution has led to a crisis in the condition of environmental resources (6-11). The major source of air pollutants are from combined cycle processes, in terms of quality and quantity of fuel com- bustion (12, 13). The emissions from fuel combustion that are the most important are oxides of nitrogen, oxides of sulfur and monoxide and are being discharged to the at- mosphere through these sources (14-16). Perhaps the greatest impact caused by air pollution is the increase in the numbers of morbidity and mortality (17-19). The other effects of air pollutants, such as nitro- gen dioxide, are sensitivity of the eyes, nose and throat, respiratory tract infections, headache, nausea, allergic reactions, chronic respiratory disease, lung cancer, car- diovascular disease and death (20, 21). Several complex factors affect the phenomenon of transfer and disper- sion of air pollutants around us. Temporal climate patterns in an area (weather conditions) and the geo- graphic area under study affect how the emissions are transferred and dispersed (22-25). On a cross-local scale, airflow or lack of airflow are two main factors that have an impact on the transition and dispersion process of pollutants (26-28). Ahigher wind speed can affect the concentration of pollutants in urban areas (27, 29). Also,