Nowadays environmental problems of the world's major cities such as poor air quality, faced citizens to serious risks. Improving air pollution monitoring due to modern technologies is a basic strategy in order to cope with the devastating effects of the environmental consequences of this century. One of the most important considerations in the implementation of an optimized air pollution control systems, is the choice of suitable locations for air pollution monitoring stations. In the present study, it has been attempted with layers of information the master plan of the city of Mashhad prepared is being prepared in 2014, in four phases, with the investigation and review of the standards and the urban area needs to be monitored, to begin determine the type of sensor, and estimate their numbers based on population density and the main strategy. So that in this strategy, the criteria for Optimal Positioning stations measuring air pollution Selected based on the kind of sensor monitoring air pollutants in the form of five criteria of green space, parking and Repair great, bus stops and taxi, energy centers and urban streets. And then weighting the criteria by AHP software Expert Choice, with overlapping layers attributed to the criteria in Arc GIS, was specified the candidates. TOPSIS in MCDM engine software used to rank candidate regions and select the best place for air pollution sensor allocation. TOPSIS estimation shows Optimum site has the highest closeness coefficient (numeric value: 0.53) among candidate sites.
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