MUMBAI: As vehicles were off the roads and people were cooped up in their homes through most of 2020, the city did become a quieter place compared to the year before, but noise levels at several of the 10 monitored locations remained above permissible limits.1According to Central Pollution Control Board data presented earlier this week in the Rajya Sabha on noise levels in the city, Bengaluru, Chennai, Delhi, Hyderabad, Lucknow and Kolkata, the highest daytime (6am to 10pm) average noise level last year among the seven cities was 77 decibels (dB) at Kukatpalli in Hyderabad.The highest night-time (10pm to 6am) average level of 73 dB was recorded at one location each in Delhi, Chennai and Hyderabad.The Noise Pollution (Regulation and Control) Rules, 2000, say the maximum noise level in silent, residential, commercial and industrial areas should be 50, 55, 65 and 75 dB in the day and 40, 45, 55 and 70 dB at night, respectively.In the city, the highest level of daytime noise was 72 dB at Andheri and CSMT. In the night, the highest noise level of 70 dB was recorded in Andheri. The Andheri monitoring station is classified as an industrial location while CSMT is a commercial location. Among the monitored locations, only Asalfa in Ghatkopar reported a higher noise level compared to 2019.While vehicles were off the roads in the first few months of the lockdown, several other restrictions on public activities continued until the end of the year. The city also recorded muted celebrations during Ganeshotsav, Navratri, Diwali and the New Year.Activists said the results showed that there was a need to identify noise sources to reduce pollution. “Since decibels are a logarithmic value, even a few units lower is a significant drop, so the city was quieter in 2020. It is always assumed that the noise is from the vehicles, but this data shows that the levels remained above permissible limit even as the lockdown was in place, indicating that a lot of it comes from recreational activities. We had several complaints during the lockdown about construction work creating noise pollution through the day and night,” said Sumaira Abdulali, convener, Awaaz Foundation, a city-based NGO.