The drive by the authorities of the West Bengal Pollution Control Board (WBPCB) and the city police to restrict the use of banned fireworks continued this Diwali, but little could be done to keep a check on the air pollution level with several indicators showing a marked rise since last year.

 Damayanti Sen, Joint Commissioner (Crime) of Kolkata Police, said here on Thursday that 713 persons had been arrested for bursting banned fire-crackers. She also said that 883 kilograms of banned crackers were seized on Wednesday.

 However, the levels of air-pollution rose significantly since last year.

 According to the records of the WBPCB, the quantity of toxic gases such as Nitrogen Dioxide and Sulphur Dioxide recorded in the atmosphere was significantly higher this year.

 The levels of Sulphur Dioxide (measured in micrograms per cubic metre) in the 24 hours ending at 6:00 a.m. on Thursday doubled at nearly all four stations of the WBPCB — Behala Chowrasta (15.82), Beliaghata (14.17), Salt Lake (18.73) and Topsia (16.30).

On November 6, 2010 the levels reported at the four stations were: Behala Chowrasta (10), Beliaghata (7), Salt Lake (9), Topsia (8).

 All four stations also reported higher levels of Nitrogen Dioxide.

 The particulate matter recorded at all four stations was more than 300 micrograms per cubic meter — three times the permissible limit of 100 micrograms. At Topsia, the level of particulate matter has jumped from 137 in 2010 to 369 this Diwali.