Air Pollution Scenario in the Himalayan Kingdom of Nepal
Nepal is a land locked country with total land area of 147,181 sq. Km. Nepal is a country with 3918 villages, 56 municipalities and one metropolitan city, Kathmandu. Kathmandu, a historical and World heritage city is situated in central part of Nepal which has been facing acute air pollution problems due to which it is affecting millions of people, as a result public concern has increased tremendously. The population growth rate in Kathmandu is above 6% and traffic vehicles by 15 %. Kathmandu valley lies in the higher pollution potential zone due to low ventilation coefficient. The percentage occurrence of calm air conditions is very high and the mixing heights are very low.
In April 2005, at the centre of the city it has been seen that the value of PM10 is 170 microgram per cubic meter. Twenty five years ago Kathmandu was one of the cleanest cities in the world, but at 2002 A.D it was reported to be second polluted in the world. In Kathmandu the pollution source are emitted by vehicular and industrial emission due to which the visual range in Kathmandu valley is decreasing at the rate of 1.2 Km per year.
This paper presents an in-depth review of previous studies, information, present challenges and improvement of air pollution in Nepal.