In the last week of March—when wildfires raged across the country, the country was shrouded in haze and harmful smoke.
Nationwide forest fires had taken the air quality to hazardous levels leaving the general public gasping for clean air.
The situation called for a public health emergency.
However, the adverse impact of air pollution and deteriorated air quality is not limited to human health.
The effects of air pollution transcend public health and can lead to massive loss of lives and property by unleashing catastrophic events like floods and landslides, according to the findings of a recent study published in Climate Dynamics, a scientific journal.
Researchers had studied the climatic impact of aerosols—a collection of solid particles or liquid droplets dispersed in the air—on clouds, precipitation, and the freezing temperatures over Himalayan foothills and the mountainous region of Nepal.
“Our findings suggest that atmospheric pollution affects the clouds, rainfall, and the free air freezing temperature,” Pramod Adhikari, co-author of the study, told the Post from the University of Nevada in Reno, United States over the phone. “Aerosols, the tiny particles suspended in the atmosphere, modulate cloud properties and hence the intensity and amount of the rainfall. Such a phenomenon can result in excessive rainfall and can cause natural disasters.”
For one of its kind study in the region, researchers—Adhikari and John Mejia, associated with the Division of Atmospheric Sciences, Desert Research Institute—analysed the long-term satellite data of 16 years from 2002 to 2017, focusing on Nepal and northwestern India, to understand the atmospheric impact of aerosols.
Researchers had then separated polluted days and clean days—280 days as polluted and 275 as clean days through a fixed parameter—to study the level of effects of aerosols on polluted and clean days.
Aerosols include dust, pollutants emitted from sources like vehicles and factories, wildfire, and construction sites, among others.
According to Adhikari, aerosols present in the atmosphere can block sunlight or radiation from reaching the surface and, as a result, increase atmospheric temperature.
An increase in temperature means the 0°C isotherm altitude, the freezing level that represents the altitude in which the temperature is at 0°C or known as the freezing point of water in a free atmosphere, is pushed further up in the atmosphere.
“What aerosols do is push freezing point up from the earth’s surface,” said Adhikari. “Our study has found that the freezing point had gone up in Nepal and the northwestern part of India on polluted days because the radiation from the sun was absorbed and the temperature had increased.”
The study recorded that the freezing point was higher by 136.82 metres on days with extreme levels of pollution in the atmosphere. And the impact of this could be evident on the ground.
“With the elevated level of freezing point, there…