Geographic information system based noise study in crowded areas of Isfahan city in 2010-2011

 The aim of this study was to evaluate noise pollution levels (NPLs) in Isfahan, compare with guideline values and providing a zoning map. 

 This study was a descriptive cross-sectional type. Totally, 19 stations were selected from most congested areas throughout the city. In determination of these stations, the Isfahan information maps of the city traffic (obtained from Isfahan traffic and transportation organization) were used. Noise parameters L 10 , L 50 , L 90 , L 95 , L 99 , equivalent sound level (L eq ), sound exposure level, sound pressure level, L min , L max , and L peak were measured using a CEL-440 sound level meter for 3 months of winter 2010-2011. The NPL and traffic noise index were calculated by a mathematical formula. All measurements were carried out twice a day (morning [a.m.] and afternoon [p.m.]) with the time interval of 0.5 h. To prepare the zoning map of the measured L eq , ArcGIS software version 9.3 was used. 

 The mean and standard deviation of the measured L eq values in the a.m. and p.m. were 74.6 ΁ 2.78 and 72.6 ΁ 4.43 dB (A) , respectively. In comparison, there was a significant difference between the average L eq values of a.m. and p.m. (P < 0.001) and both were higher than the noise guidelines suggested by Iranian environmental protection organization. The zoning maps show that the maximum L eq in the a.m. (78.3 dB (A) ) was related to Ferdowsi bridge station and in the p.m. (79.6 dB (A) ) was dedicated to Jomhoori square station. 

 It can be concluded that as in the most cases the noise levels of Isfahan exceeded from the guideline values. This city is categorized in the noisy/crowded cities in Iran. Thus, noise pollution of Isfahan can be a serious problem and investigating its reasons is recommended.