Kathmandu consistently ranks on top of one chart that I would rather have it not be a part of at all - that of the most polluted cities in the world regarding its air quality. In 2023, Kathmandu was ranked the 11th most polluted city, and Nepal was ranked the 8th most polluted country in the world, with regard to the weighted average concentration of PM2.5. Particulate matter, PM, is the mixture of solid particles and aerosols that pollute the air. PM2.5 are fine inhalable particles that are 2.5 microns in diameter. For comparison, the average human hair is 70 microns thick. So, the largest PM2.5 is 30 times smaller than the average thickness of a human hair. Scientists use a color-coded index called the Air Quality Index (AQI) with a normalized scale from 0-500 to report air quality. This index is based on the measurement of ground-level ozone, particle pollution (PM10 and PM2.5), carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide (SO2). Higher AQI values indicate higher pollution levels and thus represent a greater chance of adverse effects on human health. In April 2024, the AQI of Kathmandu was reported to be 264, which is considered very unhealthy. It is so harmful, in fact, that international health protocols advise people of sensitive groups to avoid all outdoor activities and everyone else to avoid prolonged outdoor activities. There is seasonal variation in this trend, winter being the most polluted season, and summer and rainy seasons are the least polluted.
So, what do all these numbers and rankings mean? Air pollution remains one of the major human health threats in the world, resulting in close to 8.1 million deaths/year in 2021. Air pollution is thus only second to high blood pressure in terms of risk factors correlated to death globally. In 2019, deaths caused by ambient PM2.5, ozone, and household air pollution were estimated to be around 42,100 individuals in Nepal. If we compare the data from 1990 to 2019, the deaths from household air pollution have decreased due to using clean cookstoves and reducing fossil fuels. However, the deaths from ambient PM2.5 and ozone have increased by 290% and 231%, respectively. Given these numbers, it shouldn’t be a surprise that deaths caused by air pollution far exceed deaths caused by vehicle accidents, which are around 1.28 million globally. Additionally, if we look at the broader picture, air pollution contributes to the global disease burden, encompassing early death and the number of years lived in poor health. Although air pollution is seen as a public issue around the world, it is more severe in middle to low-income countries.
Smog to stay for some more days in Kathmandu Valley
Unplanned urbanization, vehicle emissions, fossil fuel combustion, wildfire, brick kilns, constructions, etc. – one could make a long list of reasons why Kathmandu’s air is as polluted as it is currently. Nepal Health Research Council reports that 38% of the total air pollution in Kathmandu valley is due to vehicular emissions. Additionally, the geography of the city favors the trapping of dust, fumes, and harmful gases within the valley, contributing to the deteriorating air quality. Whatever the cause might be, exposure to Kathmandu’s air has several severe health consequences, especially for children, the elderly, and people with pre-existing health conditions. It not only causes respiratory diseases like asthma, bronchitis, or lung cancer, but also impacts the heart, the brain, and generally undermines the overall life expectancy of an average Kathmandu-ite.
While other political and economic issues surrounding Nepal might seem like bigger issues that require all our attention, the air pollution crisis in Kathmandu valley also requires urgent action from all stakeholders involved. While pollution is seen as an environmental issue, the conditions in Nepal and Kathmandu have turned this into a public health crisis that directly impacts every Nepali who breathes this polluted air. While the government has taken some steps to mitigate this situation, including vehicular emissions monitoring and tax breaks for EVs, more needs to be done. Urgent measures are required, including stricter regulations on emissions, promotion of clean technologies to reduce industrial smokestack emissions, a ban on open waste burning, and a focus on improving the energy efficiency of buildings. These are not the only solutions to the problems we currently face regarding air pollution, but more active participation is required from all stakeholders. It is not that we have not taken any steps towards improving air quality in Kathmandu and Nepal but plans as well as laws that have floated around need to either be implemented more strictly or better regulations are required to replace old ones.