Qualité de l’air à Kathmandu

How bad is air pollution in Kathmandu?

Kathmandu is a city located in Nepal, home to many different ethnic groups with both Hinduism and Buddhism being the main religions. It is the cultural hub of Nepal, being of importance to the country’s arts and history, as well as being the main economic zone. Currently Kathmandu is undergoing rapid growth, being one of the fastest growing cities in south Asia. As with all rapid growth and development comes a spike in pollution levels, and to compound the situation, a disastrous 7.8 magnitude earthquake that took place in 2015, levelling many areas of the city that still lay in ruin years later, which besides disrupting daily life is another source of pollution in of itself, due to large amounts of dust and finely ground particles being blown into the air from these sites.

Kathmandu came in with a PM2.5 reading of 48 μg/m³ as a yearly average over 2019, placing it into the ‘unhealthy for sensitive groups’ category, which requires a PM2.5 reading of anywhere between 35.5 to 55.4 μg/m³. This shows that Kathmandu came in on the higher end of this scale, meaning that the city is subject to some fairly bad levels of pollution year-round, with some months coming in considerably higher, such as January with a reading of 102.7 μg/m³, an extremely high number that would have placed Kathmandu into the ‘unhealthy’ bracket (55.5 to 150.4 μg/m³) at that point in time. Thus, pollution levels in Kathmandu are of concern to its citizens and their health.

What are the main causes of pollution in Kathmandu?

There are several causes of elevated pollution levels in Kathmandu, with both human and geographical factors coming together to form these heightened numbers. For a start, Kathmandu is situated in a location that places it deep within a valley and many mountain ranges around. It is also surrounded on both sides by China and India, economic giants who in their own rights still have many pollution problems, with cities from both countries often coming in ranked very highly amongst all polluted cities worldwide.

In regards to what is actually causing the pollution in Nepal, the large assortment of vehicles, many of which are ancient and running on outdated motors and diesel fuels would be responsible for pouring out high concentrations of fumes and noxious pollutants. Other sources include open burning of organic material as well as refuse, as with a lack of proper infrastructure comes problems pertaining to garbage collection and disposal, and as such many people resort to setting fire to their waste. This would cause a lot of fumes that come from the combustion of materials such as wood and plastic, all of which have many negative consequences on human health.

So, to summarize, the main causes of pollution in Kathmandu are open burn fires, vehicular emissions, dust from construction sites and damaged areas left over from the earthquakes, all compounded by its geographical location, lacking the elevation and wind to allow these pollutants to disperse properly, instead accumulating and rising to dangerous levels.

What are the main types of pollutants found in Kathmandu?

With many open burn sources and different types of outdated vehicles operating around the city, a large amount of pollution would come from combustion sources. Among them would be fine particulate matter such as black carbon, which is formed from the incomplete combustion of fossil fuels as well as organic material such as wood or plants. With these outdated vehicles often relying on diesel fuels, they would be pouring out large amounts of black carbon in the form of soot, which can permeate the atmosphere in areas of high traffic as well as coating roadsides and underpasses with thick black accumulations, not only being visually unappealing but having a host of carcinogenic properties. Other pollutants arising from vehicles would include carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃) and sulfur dioxide (SO₂).

When are the most polluted months in Kathmandu?

Observing the data gathered over 2019, the months that came in with the cleanest readings of PM2.5 occurred in the middle portion of the year. PM2.5 refers to particulate matter that is 2.5 micrometers or less in diameter, and due to its small size and subsequent dangers to human health, is used as a major component in calculating overall air quality.

The cleanest month of 2019 was august, which came in with a reading of 11.8 μg/m³, putting it into the ‘good’ rating bracket, which requires a number between 10 to 12 μg/m³ to be classed as such, making it a bracket with a very fine margin of entry, and of note is that the air during this time of the year would be significantly healthier to breathe than other times.

The months with the worst readings were January through to May, as well as November and December, making the beginning and end of the year the time that pollution levels are at their highest. These pollution levels reached an absolute peak in January, with a reading of 102.7 μg/m³, followed by December with a reading of 75.6 μg/m³. In total, six months out of the year came in with unhealthy air quality ratings.

Is air quality improving in Kathmandu?

With existing data taken from the previous years, it is uncertain as to whether pollution levels in Kathmandu are improving or just fluctuating between different numbers that have similar levels of pollution. In 2017, a PM2.5 reading of 45.9 μg/m³ was recorded. This was followed by a fairly large increase the next year in 2018 of 54.4 μg/m³, showing that pollution between 2017 and 2018 had gotten significantly worse.

Moving into 2019, it is apparent that there was visible improvement, with its PM2.5 reading of 48 μg/m³. However, when compared to 2017’s reading this still shows a decline in air quality. As such the pollution levels in the year of 2020 and beyond will show whether the air quality in Kathmandu is actually improving and not just moving up and down by a few units each year.

With a city that is undergoing such a marked increase in its economy and all the growth associated with it, there will be a large amount of environmental challenges ahead as many developing cities in Asia have been witness to, many of which are still going through them. With a reduction in the amount of diesel fuel vehicles as well as open burn sources being cracked down on, Kathmandu may be able to see some form of improvement in its air quality in the years to come.