Adverse Health Consequences of Poor Air Quality in Nepal: A Wake-Up Call

Abstract

Literatures shows that poor air quality index (AQI) is associated with several adverse health impacts, such as asthma, chronic obstructive pulmonary disease, diabetes mellitus, tuberculosis, cancer, pneumonia, cataracts, heart diseases, and mental health disorders. Nepal, one of the lower-middle-income countries, has become vulnerable to adverse health impacts due to poor AQI over time. The capital city of Nepal, Kathmandu, is frequently placed as one of the most polluted cities by IQAir. As such, this statement marks a caution for policymakers and the public to be aware of the future effects of prolonged exposure to air pollution and highlights its causative factors. To solve this burgeoning issue, because of the significant rise in urbanization and population growth, mitigation strategies such as creating awareness, reducing vehicular emission, reducing forest fires, creating and identifying vulnerability maps risk zones for forest fires, switching to electronic vehicles and personal interventions such as staying indoors and reducing physical outdoor activity, wearing face masks must be focused and given priority. Although our study is limited in its methodology and findings, it helps establish a policy base to underscore the need for longitudinal cohort studies to generate further evidences pertaining to not up to par air quality levels and their subsequent health impacts in the Nepalese population.

Highlights

● Literature shows the growing cases of respiratory illness and non-communicable diseases, such as chronic obstructive pulmonary diseases, diabetes, heart diseases, mental health diseases, and cancer, due to poor air quality index (AQI).

● Nepal, a lower-middle-income country, is also getting vulnerable in developing poor AQI due to growing population and urbanization.

● Pollutants such as Particulate matter (PM) 2.5, carbon monoxide, ozone, nitrogen dioxide, and sulphur dioxide pose a huge risk to human health.

● Several factors exacerbating adverse health consequences in the case of Nepal due to poor AQI are due to a rise in the PM2.5, greenhouse emissions, forest wildfires, and emissions from diesel-powered vehicles.

● Updating Nepalese policies regarding vehicular pollution, reduction of emissions from the industrial sector, empowering the idea of zero-emission vehicle policies, reduction of forest fires, and personal interventions such as wearing masks, avoiding outdoor activity when the air quality is poor are crucial.

Background

With rapid population growth and urbanization, Nepal, a lower-middle-income country (LMIC) has become increasingly vulnerable to the harmful effects of air pollution, which now poses a significant threat to public health. ¹ As of March 2, 2025 Kathmandu’s air quality index (AQI) was 168 as per IQAir (https://www.iqair.com/nepal/central-region/kathmandu), which is categorized as unhealthy due to high levels of the pollutant being Particulate matter (PM) 2.5 with a concentration of 80.3 $\frac{\mu g}{m^3}$ . ² This level of air is unhealthy as it falls under red Zone AQI (range:151-200), ³ posing an elevated risk for health problems which are often overlooked, especially the detrimental effects of PM. ⁴ AQI values greater than 100 represent a greater risk for sensitive people, along with public health concerns. ³ As we write this paper, according to the Environmental Performance Index 2024, Nepal ranks 175th out of 180 countries for air pollution. ⁵ Kathmandu is constantly found to have AQI falling into the “Unhealthy for sensitive group” and “Unhealthy” categories, especially in the winter seasons. ¹ In this perspective paper, we try to highlight the adverse health impacts of air pollution along with its responsible factors and mitigation strategies with a focus on Nepal.

Adverse Health Consequences

Literature show that poor AQI is responsible for respiratory illness and non-communicable diseases (NCDs) such as chronic obstructive pulmonary disease (COPD), acute respiratory conditions, diabetes mellitus, tuberculosis, cancer, pneumonia, cataracts, and heart diseases.^3,6 Pollutants such as PM2.5, carbon monoxide, ozone, nitrogen dioxide, and sulfur dioxide pose a huge health risk. ⁶ Various pulmonary (COPD, asthma, lung cancer), cardiovascular (coronary artery calcification, carotid intima thickness, hypertension and stroke) and neurological diseases (neuroinflammation, autistic spectrum disorder, Alzheimer’s disease) have been linked to PM_2.5.^{7 -10} Even short-term exposure to increased levels of PM2.5 can lead to decreased lung function and exacerbation of asthma in children and adults. In contrast, long-term exposure to PM2.5 increases a person’s risk of NCDs severely. ⁶ Vulnerable populations such as pediatrics, the older adults, and pregnant women are at further risk of air pollution, where pregnant women’s exposure to high levels of PM2.5 is associated with poor birth outcomes. ⁶ The exposure to air pollution begins from the uterus through its accumulation in the placenta, leading to its potential deleterious consequences in fetal neurodevelopment as well as age-related neurodegenerative diseases. ¹¹ Besides the direct consequences, the mental health impacts of exposure to air pollution are also well established, as literature highlights how the increased concentration of pollutants is linked with affecting the brain, stimulating several neuroinflammatory mechanisms, thus leading to mental conditions such as depression, psychosis, mood disorders, dementia, and several mental health illnesses. ¹² The ultrafine, fine, and coarse PM, through olfactory bulb transmission, nasal epithelial transmission, and mechanical inhalation pathways, exhibits multiple adverse effects on the brain, leading to various mental health consequences. ¹³ Schizophrenia spectrum disorder, depression, and anxiety disorders were found to be associated with PM_2.5. ¹⁴ Similarly, exposure to poor air quality can contribute to compounded risks from high temperature and humidity, and extended exposure to noise causes substantial mental stress among workers, leading to degraded quality of life. In addition, loss of income due to absentees in the workplace and increased medical expenditure further pushes the vulnerable population into the vicious cycle of the poverty trap. ¹⁵

Factors Exacerbating Negative Health Consequences

Looking at data from recent years, Nepal has observed a serious environmental and public health risk, with pollution levels 4.9 times higher than recommended guidelines by the World Health Organization. ¹⁶ In comparison among South Asian nations, Nepal was found to have the largest rate of rise of carbon dioxide, 16.97 million tons, in 2020. ¹⁷ Similarly, greenhouse gas emissions of 54.6 million tons of CO₂-equivalents, methane emissions of 31 million tons of CO2-equivalents in 2018, and nitrous oxide emissions of 31 million tons of CO2-equivalents in 2019 were observed. ¹⁷ One of the significant contributors to pre-monsoon pollution from March to May remains wildfires. ¹⁸ A study conducted in one of the national parks and districts of Nepal shows that forest fires were responsible for increased air pollutants, ¹⁹ and endotoxin concentration, along with the emission of anti-inflammatory agents too. ⁴ At the same time, another significant contributor could be emissions from diesel-powered vehicles, which are considered more pollutant and carcinogenic than petrol-powered ones. ¹ In addition to these, with the growing focus on sound insulation and energy-efficient buildings, there has been an increase in exposure to air pollutants of indoor origin (PM, nitrogen dioxide, carbon monoxide) and its accumulation due to decreased ventilation. These designs are associated with low-grade fatigue and poor mental health, particularly referred to as “sick building syndrome” due to lower air quality. ¹³

Mitigation Strategies and Prospects

The increasing context of air pollution, poor AQI, and the growth of several NCDs underscores a coordinated need to update Nepalese policies regarding vehicular pollution, industrial sector on reducing the emission of pollutants, zero-emission vehicles policies, and reduction of forest fires through management and preparation of forest fire policies. To reduce forest fires, one model could be the integration of forest fire vulnerability risk maps within the forest department to ensure timely prevention and eliminate the risk of future unprecedented events.^20,21

Moreover, cross-border regional collaboration is paramount in reducing transboundary air pollution concentration. When air pollution is elevated and reaches the maximum level, personal interventions can be conducted, such as wearing masks, avoiding outdoor physical activity, and staying indoors. ²² Additionally, with the implementation of air pollution control interventions at the government level, special focus should also be given to urban and built environment designs for better indoor air quality.

Given the nature of our study, this study is limited to the methodology section without including robust statistics. However, because of the existing literature focused on several adverse health impacts, this study can act as an evidence base in initiating several longitudinal cohort studies. Similarly, this study can also act as a tool for creating awareness in schools, the public, and through mass media about air pollution, along with its mitigating strategies.

Conclusion

Poor air quality is associated with adverse health impacts. The growing urbanization, vehicles, and population growth in the Nepalese context also fuel the increasing air pollution, thus putting the entire Nepalese population further at risk of adverse health impacts. Policymakers must facilitate the creation of guidelines that focus on reducing air pollution, along with its inspection and supervision.