Motorcycles and private cars are the main sources of noise pollution in the country's major cities, followed by public buses, says a new survey of the Department of Environment (DoE).

The survey shows that public buses contribute to relatively less noise than the other two modes of transport, which indicates that introduction of public transportation can check the sound pollution in these cities.

The survey, conducted in eight cities earlier this year, reveals that motorbikes and cars, on an average, generate 95 decibel (dB) noise each in the capital while buses contribute to about 44dB.

In Chittagong, motorcycles and private cars generate 100 decibel (dB) sound each while public buses about 82dB. In Sylhet, both motorcycles and cars produced nearly 84dB noise and buses generate 40dB sound.

The survey data shows that maximum 85dB of sound is generated from motorcycles in Khulna, followed by 77dB from private cars and 60dB from public buses. In Barisal, motorcycles generate about lOOdB noise on an average while 76dB noise comes from private vehicles and 42dB from public buses.

In Rangpur, motorcycles produce about lOOdB noise while private vehicles 98dB and public buses about 66dB. Motorbikes con-

tribute to 80dB sound in Rajshahi while private cars 68dB and buses 46dB. In Mymensingh, the DoE data says, motorcycles and private cars contribute to 88dB of sound each while public buses about 66dB.

According to Bangladesh Road Transport Authority, there were 19.86 lakh registered motorcycles in October last, while 3.27 lakh cars and 43,154 buses across the country.

The number of the country's registered motorcycles increased to 19,85,376 in October 2017 from 7,59,257 in 2010.

In Dhaka metropolitan area, there were some 4.84 lakh registered motorcycles in August, according to the BRTA statistics.

The number of registered private cars is 2.55 lakh, while that of buses is 30,274 in the city.

According to the Noise Pollution (Control) Rules 2006, the acceptable sound condition for Bangladesh is 50 decibel (dB) for daytime and 40dB for night in silent areas; 50dB for daytime and 45dB for night in residential areas; 60dB for the daytime and 50dB for night in mixed areas (residential, commercial and industrial localities); 70dB for daytime and 60dB for the night in commercial areas and 75dB for daytime and 70dB for the night in industrial areas.

The World Health Organization says generally 60dB of sound can make a man deaf temporarily and lOOdB of sound can cause complete deafness.