TOI looked at 24-hour average noise levels (LAE) or sound exposure levels between June 1 and June 7 at Anand Vihar, East Arjun Nagar, Civil Lines, ITO, RK Puram and Punjabi Bagh. RK Puram and Punjabi Bagh—categorised as "quiet area" and "residential area", respectively—recorded more than 65 dBa on most days.

Noise Pollution Rules 2010 recommend a standard of 65 dBa for day and 55 dBa for night in commercial areas. In residential colonies, the levels should be 55 dBa for day and 45 dba for night. If the noise level exceeds the standards by 10 dBA at any location, it can be recorded as a "violation" and penalised by the authority concerned.

For example, if there is excessive honking, traffic cops can impose a fine of Rs 100. Ironically, Delhi traffic police don't have the equipment to monitor noise at intersections. But the noise pollution problem in the capital is far larger than just some random honking cases. CPCB's 'Status of Ambient Noise Levels in India' for 2015-16 had highlighted that locations like ITO, Delhi Technological University (DTU) on Bawana Road and NSIT, Dwarka didn't meet noise standards all year round. Former environment minister Anil Madhav Dave had informed the Rajya Sabha recently that 70 monitoring stations in Mumbai, Lucknow, Delhi, Kolkata, Chennai and Bengaluru were monitoring noise levels and "the data from these monitoring stations indicate that average noise pollution levels generally exceed the permissible limits".

Despite such a trend, both civil society organisations and the government continue to maintain silence over the matter. Some experts say the noise pollution guidelines are "flawed." "The guidelines should specify whether they are meant for 24-hour average or levels in real time. Due to lack of clarity, authorities tend to interpret the norms in their own ways," said a government scientist.

According to Nasim Akhtar, a senior scientist at Central Road Research Institute, heavy vehicles are responsible for a major part of the noise pollution in Delhi. "One truck causes as much noise as 7-8 cars. In addition, every time there is an increase in noise by 10 dBa, the loudness is doubled. This affects people's health. While our guidelines are similar to those in Europe, residential areas in European cities are 200 to 300 metres away from the road. There is also a buffer zone between the road and houses in those cities. In India, people are exposed directly to road noise," he said.

Akhtar wondered why noise pollution, unlike air pollution, was not treated as a health hazard when there is enough evidence showing its impact on health. The rules for silence zones (100 metres around hospitals, educational institutions, courts, religious places) are violated everywhere. Akhtar explained that the problem of noise from banquet halls or religious ceremonies was hardly anything compared to that from traffic. CPCB scientists said an "action plan" was prepared following their 2015-16 report, but it's yet to be made available in the public domain.

WHO guidelines recommend less than 30 dBA in bedrooms for a good night's sleep and less than 35 dBA in classrooms to allow ideal teaching and learning conditions. According to Dr Salabh Sharma, an ENT consultant at Sir Ganga Ram Hospital, there is no adequate data yet to establish whether noise pollution alone is behind increasing cases of partial and full hearing loss. "But we are seeing a rise in such cases in the past 15 years...Noise pollution damages the hair cells inside the cochlear. These problems are also being seen among relatively younger people. This can have adverse effects at a subconscious level, resulting in irritation and tiredness," he said.