Particulate Matter and Risk of Hospital Admission in the Kathmandu Valley, Nepal: A Case-Crossover Study

Abstract

Air pollution is known to lead to a substantial health burden, but the majority of evidence is based on data from North America and Europe. Despite rising pollution levels, very limited information is available for South Asia. We investigated the impact of particulate matter with an aerodynamic diameter less than or equal to 10 μm (PM10) on hospitalization, by cause and subpopulation, in the Kathmandu Valley, an understudied and rapidly urbanizing region in Nepal. Individual-level daily inpatient hospitalization data (2004-2007) were collected from each of 6 major hospitals, as Nepal has no central data collection system. Time-stratified case-crossover analysis was used with interaction terms for potential effect modifiers (e.g., age, sex, and socioeconomic status), with adjustment for day of the week and weather. Daily PM10 concentrations averaged 120 μg/m3, with the daily maximum reaching 403 μg/m3. A 10-μg/m3 increase in PM10 level was associated with increased risks of hospitalization of 1.00% (95% confidence interval (CI): 0.62, 1.38), 1.70% (95% CI: 0.18, 3.25), and 2.29% (95% CI: 0.18, 4.43) for total, respiratory, and cardiovascular admissions, respectively. We did not find strong evidence of effect modification by age, sex, or socioeconomic status. These results, in combination with the high levels of exposure, indicate a potentially serious human health burden from air pollution in the Kathmandu Valley.

The Threat of Ambient Air Pollution in Kathmandu, Nepal

“…Only few studies on this regard have been done in region like Nepal. It has been found that, with high level of air pollution exposure, Nepal, especially Kathmandu, is suffering from a potentially serious human health burden from air pollution [ 30 ]. Air pollution has long been regarded as a silent killer responsible for causing a variety of chronic and infectious diseases.…”

“…In Nepal, along with the rapid and uncontrolled urbanization and haphazard developmental projects, people are being victimized with serious airborne diseases. Though few studies and publications have been done regarding air pollution in Kathmandu, the city has now been regarded as severely polluted place [ 30 ]. This article hence emphasizes highlighting the effects, sources, status, and threats of air pollution in Kathmandu Valley.…”

The association between high particulate matter pollution and daily cause-specific hospital admissions: a time-series study in Yichang, China

“…The majority of the evidence on the associations between PM pollution and hospitalizations has been from North America and Europe, but the exposure levels in these regions are substantially lower than elsewhere, such as in major cities in China (Gurung et al 2017). A meta-analysis (Newell et al 2017) on the effects of PM has demonstrated variations in cardiorespiratory morbidity and mortality between regions for exposure to both PM2.5 and PM10.…”

Effect of the COVID-19 Lockdown on Ambient Air Quality in Major Cities of Nepal

“…17 However, PM less than 10 μm (PM 2.5 and PM 10 ) is of highest importance as it poses the most serious risks to human health. 15, 19,20 Epidemiological studies have shown positive associations between exposure to PM and frequency of certain illnesses and mortality. Exposure to fine PM is associated with a number of cardiovascular outcomes such as hypertension, atherosclerosis, arrhythmias, myocardial ischemia, heart attacks, heart failure and strokes.…”

“…Similarly, a 10 µg/ m 3 increase in PM 10 was found to increase risk of hospitalization by 1.70% for respiratory and 2.29% for cardiovascular admissions. 19 A significant increase in the number of automobiles has created an alarming air pollution problem in Nepal, especially in densely populated cities like the Kathmandu valley. 22 In fiscal year 2018-19, 318 477 new vehicles were registered, of which 78% were motorcycles and 6% were cars/vans.…”