摘要：CO is one of the main air pollutant which leads to many problems for human. Mega cities such as Tehran have critical issues by increasing the vehicles, fuel usage and urban area expansion. Hence, to have a clear view points on the pattern of CO concentration in Tehran, the data of 14 air quality concentration centers in a midterm period (2009 and 2012) are used. The main novelty of this research is using the third quartile (Q3) as the pollution indicator which leads to more accurate results based on the exposure pattern in a day. Additionally, by Spline interpolation model and using ArcGIS software the zoning maps to show the CO concentration in urban area are illustrated and discussed. Using Q3 instead of the mean values showed more accurate results due to the exposure patterns. Due to the results, the CO concentration shows a downward trend and the most changes are in the Western side of the city.
