NEW DELHI: Delhi may be the dirtiest city in terms of high air pollution but the dubious distinction of being the noisiest city goes to Mumbai which reported the maximum violation of safe noise levels for consistently longer periods during 2011-14. Delhi, in fact, was at number four as Lucknow and Hyderabad turned out to be noisier than the capital which has an advantage of relatively higher green cover and road side plantations. Though the most common source of noise pollution is motor vehicles, the other sources like generator sets, office machines, aircraft, industrial and construction activities too substantially contribute to increasing the noise level in the cities. The observation came from the Central Pollution Control Board (CPCB) which in its latest report also noted how the noise pollution (noise level beyond the prescribed limits of 55 dB during day and 45 dB during night) can cause aggression, hypertension, hearing loss, tinnitus and sleep disturbance."Tinnitus can lead to forgetfulness, severe depression and at times panic attack," said the country's national pollution watchdog that compiled the real time monitoring data from 35 locations in seven cities and flagged its conclusion by averaging the location-wise day time and night time noise level. The reason behind coming out with such a database is to help policymakers in setting standards and policy formulation for controlling noise pollution. Such data is also required to ensure compliance of existing rules.Though the noise level is currently monitored at 35 locations in seven cities, the CPCB plans to set up monitoring stations at 160 locations across 18 states in due course.At present, the noise level in Delhi is monitored at ITO, Dilshad Garden, Delhi College of Engineering (DCE), NSIT Dwarka and CPCB headquarters in East Arjun Nagar.Dilshad Garden, DCE and NSIT monitoring stations in Delhi showed the average noise level within the prescribed limits of 55 dB. The CPCB also came out with recommendations to check noise pollution, including creation of vegetation buffer zone, road side plantations, strict enforcement of noise level standards for fire-crackers, loud speaker and public address system.