Eco system: Kolkata is a highly polluted district. According to an Institute of Ecological Exploration Report, in 1984, there are only 21 trees per km in Kolkata, far below the standard mark of 100 trees per km. The per capita open space at 20 feet2 is too low. With these handicaps, the smoke from vehicles and industrial units, coupled with winter fogs, create a polluted environment. Noise pollution levels are also high. The noise tolerance level of average human beings is 60–65 decibels. The noise pollution levels in some areas are as follows: Binay–Badal–Dinesh Bag 80 – 85 dB, Esplanade 70 – 84 dB, Park Street 78 – 81 dB, Gariahat 80 – 82 dB and Shyambazar 80 – 82 dB. Spread over 12,500 hectares the East Kolkata Wetlands play a very vital role in maintaining the ecological balance in the neighbourhood of Kolkata. KMC dumps 2,600 tons of solid waste daily. In addition liquid sewage, toxic effluents and polluted air are recycled into clean air, fresh water, organic nutrients and a daily supply of fresh fish and green vegetables for Kolkata kitchens. The surrounding countryside continues its subsistence living with the help of this eco-system.