A quiet start to Diwali on Thursday gradually crescendoed to the usual noisy night.

Residents across the city said they heard firecrackers go off from around 6pm, long before the two-hour window to burst green crackers.

Calcutta High Court allowed only green firecrackers on Diwali, which could be burst between 8pm and 10pm.

From the noise, it was easy to tell that the stuff exploding was far from green. The permissible noise level of legal firecrackers is 125 decibel at 4m from the source.

“Seven persons were arrested for bursting illegal firecrackers and 26 people were arrested for disorderly conduct,” said a senior officer of Kolkata Police.

Residents of Ballygunge, Salt Lake, Kasba, Behala and localities along VIP Road said in the afternoon that it seemed the city would fare better this year.

But there were ominous signs around 6am and by 7, the soundscape had changed. “From around 7.30pm, there was indiscriminate bursting of firecrackers. I could hear crackers every few seconds,” said a resident of Kasba.

Ballygunge was no better. As were Behala, Salt Lake and Baranagar.

A woman who was travelling from Esplanade to Gariahat around 7.30pm said she frequently heard cracker explosions on Camac Street and in Bhowanipore and Hazra.

In Lake Town, Baguiati, Salt Lake, New Town and Rajarhat, crackers started going off in ones and twos in the afternoon.

The pops and bangs soared around 6.30pm.

Avishek Ghosh, a resident of BJ Block in Salt Lake, said he could hear crackers going off since the afternoon. “We could hear the sound of crackers since the afternoon but the frequency dropped a bit around 5.30pm only to rise after 7pm,” Ghosh said.

A senior officer of the Bidhannagar Police Commissionerate said they had responded to at least a couple of complaints of violation of firecracker rules from New Town and Rajarhat.

“When our teams reached the areas, those bursting fireworks showed our officers the boxes in which the items had been packed. All the boxes had the markings of green fireworks. Which means they conformed to the sound norm. But since they violated the law by bursting crackers before the court-mandated window, we issued them warnings. They stopped bursting crackers and promised to abide by the rule,” a senior officer of the Bidhannagar commissionerate said.

Twenty-five complaints were lodged with the PCB till 11.10pm. About 15 were from Calcutta, said a PCB official.

In Calcutta, the complaints came from Naktala, Netaji Nagar, Kasba, Rajdanga and Beleghata, among other places. Those were about using loudspeakers or bursting crackers before the two-hour window.

“Many of the complaints were about bursting crackers before 8pm. Two complaints, about using DJs sets, came from Naihati and Arambag,” said an official of the PCB.

“DJ sets” or “DJ music” refers to the use of multiple loudspeakers to amplify the noise.

The PCB has two numbers — 18003453390 (toll free) and 033-22023057 — where people can lodge complaints about noise norm violations. On Friday, the numbers will be functional from 5pm till 10pm.

The PCB had in October 2021 announced a “complete ban on the sale and bursting of all kind of firecrackers, except green crackers”.

Calcutta High Court has also prohibited the sale and use of all crackers, barring green crackers. In an order on October 11, 2022, the court asked the PCB and the police to ensure that “there is no importation, sale and bursting of crackers other than the green crackers”.

Data recorded at 10 real-time noise monitoring stations in Calcutta showed the permissible level had breached at nine of them around 8pm.

The stations where the limit was breached are located in New Market (on SN Banerjee Road), SSKM Hospital, Kasba Gole Park, Satyajit Ray Park in Patuli, Taratala, Bagbazar, Tollygunge, RG Kar Hospital and Birati Neelanchal.

The only station where the noise was within the limit was at the state pollution control board headquarters in Salt Lake.

The limit for industrial areas is 75 decibel (6am to 10pm). The limit for commercial and residential areas is 65 and 55 decibel, respectively, during the same period. The limit for silent zones from 6am to 10pm is 50 decibel.
Birati, Bagbazar and Satyajit Ray Park are residential areas, while New Market, the PCB headquarters and Tollygunge are in commercial zones. Kasba Gole Park and Taratala are under the industrial category. RG Kar and SSKM hospitals are silent zones.

“Firecrackers were a contributing factor to the noise readings. However, ambient noise produced by traffic and microphones also add to the noise level in a place,” said a PCB official.

Naba Dutta, the general secretary of Sabuj Mancha, an association of environment workers, said he apprehended more violations on Friday.

“The police and the administration were vigilant on Thursday. They will not be so vigilant on Friday and I fear the violations will be more widespread,” he said.

“Firecrackers were sold in large numbers and people stocked up. They will burst the crackers they have purchased. If the government wants to stop the menace, they should crack down on the sale of illegal crackers,” he said.