survey of noise pollution levels in congested areas of isfahan, iran

background: to prevent the adverse health effects of noise pollution and to achieve the recommended standards, assessment of noise levels in the cities is essential. the aim of this study was to evaluate noise pollution levels (npls) in isfahan, iran and compare them with recommended standard values. materials and methods: a total number of 19 measurement points were selected from most congested areas throughout the city. environmental noise parameters such as l 10 , l 50 , l 90 , l 95 , l 99 , l eq , sel, spl, l min , l max , and l peak were measured using a cel-440 sound level meter. npl and traffic noise index (tni) were calculated by mathematical formulas. all measurements were carried out twice a day (morning and afternoon with 30 minutes intervals. finally, the average results were reported. results: the maximum l eq was at ferdowsi crossroads in the morning (78.3 db) and at jomhoori square in the afternoon (79.6 db). the mean measured l eq level was 74.5 ± 2.78 db in the morning and 72.6 ± 4.43 db in the afternoon. significant differences with the standard values were seen between average equivalent sound levels both in the morning and afternoon (p < 0.001). in other words, the obtained l eq levels were higher than standard. furthermore, there was a correlation between the calculated npl and tni in the morning and afternoon (pearson's correlation coefficient = 0.877, p < 0.001(. conclusion: it can be concluded that isfahan is an environmentally noise polluted city. in most cases, the noise levels exceed the recommended levels by iranian environmental protection organization.