Air Pollution: Silent Killer in Kathmandu valley

Fig: Kathmandu valley covered with thick air pollutants.

Subarna karki

Human body needs approximately 25 kg of air per day to fulfil oxygen requirement (CEN 2002). Any contamination in the air will have a different impact on our health. Simply the component that alters the inherent compositional property of air are termed as air pollutants. It may be natural or  anthropogenic. The major air pollutants are Nitrogen oxides (NOX), sulphur dioxide (SO2), carbon monoxide  (CO), hydrocarbons, ozone, lead, and particulate matter (CEN 2002).

Now air pollution is the major issue in Kathmandu valley and is continuously increasing year by year. Population index 2016 called the third most polluted city in the world is Kathmandu after Tetovo, Macedonia and Cairo. The growing population, Haphazard urbanization and increase in vehicles density are major pollutants in the early days. Besides this unplanned road expansion and digging of road for pipelines of Melamchi water supply project are main reason now-a-days. Kathmandu is highly vulnerable as it is valley. The surrounding hills restrict proper air movement and trap pollutants inside.

The annual population growth rate in the valley is 4.7 percent and annual motorisation is 12 percent. A health research based samples of total suspended particles collected in 2013-14 showed Kathmandu valley has a high amount of polycyclic hydrocarbons which are mutagenic and carcinogenic. Particulte matter (PM) include dust, dirt, soot, smoke and liquids droplets. Medical science considered PM-2.5 is life killing carbon. Normal surgical masks can’t block PM-2.5 from being inhaled. According to World Health Organization (WHO) guidelines, the amount of PM-2.5 should not cross 10 micrograms per cubic metre air, but in Kathmandu valley the maximum permitted level is 80 micrograms per cubic metre air.

The effect of air pollution is high in human health. High exposure in air pollution may cause chronic bronchitis, lung cancer, asthma and other respiratory problems. It also affects cardio vascular system and nervous system (Lahiri, 2003). Particulate matter is the main cause of air pollution in Kathmandu valley, which not only affects the health but also the tourism industry and lowers the human productivity.


  1. CEN/CANN, 2014, Air quality monitoring at major Traffic intersections of Kathmandu.
  2. The Himalayan Times.
  3. Clean energy Nepal.




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