The Punjab Pollution Control Board will be keeping a strict vigil on the level of pollution in the city on Diwali. The department has been monitoring noise pollution for the last four days. When fireworks will light up the skylines of the city, devices installed in major areas of the city will be monitoring the pollution caused during the festival. As part of its annual exercise, the department has made arrangements to monitor the air and noise pollution levels during the festival. The level of noise pollution will be checked by a DV meter while that of air pollution will be recorded with filter papers. The authorities have divided the city into three major zones, commercial, residential and sensitive. The sensitive zones include hospitals, educational institutions and religious places. Harbir Singh, a senior official from the department, said like every year, the board has installed pollution-monitoring devices in residential, commercial and sensitive zones. RSPM concentration highest in city According to the last year's data with the PPCB, the concentration of respirable suspended particulate matter (RSPM) in the main cities of Punjab has declined. The residential areas of Ludhiana topped in terms of RSPM concentration last Diwali. The RSPM concentration in Ludhiana was 365 microgram per cubic metre, much higher than the permissible limit of 100 µg/m3. Against the permissible limit of 55 decibels, the noise pollution level in residential areas of different Punjab cities in the past two years had varied between 75 db and 90 db.