Traffic noise pollution assessment along the Ring Road of Kathmandu Valley, Nepal

Sound or noise pollution has become a pressing issue in the major cities of the world. The rapidly growing and densely populated Kathmandu city in Nepal is no excep-tion. Traffic noise level data were recorded in the field using sound-level meters. Each observation session was for 3 h (8–11 am) and (3–6 pm) at an interval of 10 sec on working days. The vehicle flow status was studied by direct observation, while the time series of noise pollution data and vehicles registered were updated from secondary sources. Further, various noise descriptors like traffic noise level, noise pollution level, equivalent continuous sound level ( L eq), minimum sound level and maximum sound level were determined to assess noise pollution. It was found that there was no significant difference in the descriptors between the morning and evening traffic flow periods at a 5% level of significance. At all the 20 studied road junctions, L eq exceeded 70 dB(A) surpassing the recommended levels of national as well as international noise standards. If the present noise pollution level persists in Kathmandu with the growing population and number of vehicles, it will increase the chances of adverse health effects on the population.