Temporal and spatial evaluation of environmental noise in urban area: a case study in Iran

Environmental noise pollution is a disrupting factor in the urban areas which can lead to adverse health effects, behavior and quality of life. Present study was carried out in Tabriz (Iran) and aimed to achieve a real condition of noise pollution. Thirty-five measurement stations were selected, and noise levels were recorded. The equivalent noise level in (A) frequency weighting network, route-mean-square sound pressure level, minimum sound pressure level, maximum sound pressure level and noise pollution level were computed as applicable indices. Temporal and spatial variability of these noise indices were plotted by Arc GIS. Public awareness about the noise pollution was assessed through interview. Mixed model and pairwise comparisons were used for comparison of noise indices based on stations and times. It was found that noise levels were significantly different and higher than permissible levels at most stations, especially at heavily travelled crossroads and squares. Mean equivalent noise level for morning, noon, afternoon and night was 71.35 ± 7.49, 71.63 ± 4.90, 70.67 ± 4.52 and 68.74 ± 5.22 dB(A), respectively. The noise indices of all stations and measurement times had significant difference (p value = 0.028 and 0.019, respectively). It was observed that in normal traffic, the highest sound levels are produced by buses, trucks and motorbikes due to low-technology engines. Using the horn was the first reflex of the most drivers. A main part of the noise pollution problem of the studied city can be attributed to driving culture and non-compliance with traffic laws.