Darjeeling to join the list of polluted cities of West Bengal, reveals study

Researchers said that the findings raised concerns about uncontrolled tourist influx, unplanned urbanisation, unauthorised land use, biomass and combustion activities

A toy train in the heart of Darjeeling town. A recent study has shown that the Queen of Hills is on the way to join the list of polluted cities in West Bengal. The study has pointed out that the steam-driven Toy Train is also a secondary contributor to pollution. | Photo Credit: Debasish Bhaduri

A recent study by scientists has revealed that Darjeeling, the queen of hills and a popular tourist destination may be on the way to becoming one of the most polluted cities of West Bengal.

The results of the study published in a paper titled ‘PM10 within Indian standard is achievable by mitigating the sources of PM1: A thirteen years (2009–2021) long study and future prediction (2024) over the eastern Himalayas, India’ , has come as a shock to not only the people of Darjeeling but also to millions of visitors who throng the hill station every year.

“The present study throws light on one of the geographically, climatically, and ecologically important high-altitude Himalayan stations in India where people have been contributing as well as experiencing huge pollution loads but remained out of sight of the policy makers. The study raises a serious concern in front of the policy makers that a high-altitude tourist station like Darjeeling in the eastern Himalayas would soon become a non-attainment city,” the paper stated.

The six cities in West Bengal that are considered non-attainment cities and did not meet the national ambient air quality standards were Asansol, Durgapur, Kolkata, Howrah, Haldia, and Barrackpore. There are 131 cities across India that are considered non-attainment cities.

Non-attainment city

The research, spanning from 2009 to 2021, focused on characterising PM10 levels (very small pollutant particles found in dust and smoke) in Darjeeling. It determined that summer (March-May) and winter (December-February) were the two seasons in Darjeeling when PM10 concentrations exceeded 70 micrograms per cubic metre of air, surpassing the Indian standard of 60 micrograms per cubic metre.

“Despite its geographical, climatic, and ecological importance, Darjeeling has remained overlooked by policy makers. The study raises concerns that Darjeeling may soon become a non-attainment city, emphasising the necessity for Central and State pollution control boards to establish robust and continuous monitoring stations for air pollutants in such regions,” Abhijit Chatterjee, Associate Professor at Bose Institute, Kolkata and one of the authors of the study, said.

Abhinandan Ghosh of the Indian Institute of Technology, and the lead author of the publication pointed out that the projections raised serious concerns as PM10 levels were expected to exceed 105 in summer and 90 in winter.

“Moreover, ultrafine particulate matter (PM1) is predicted to approach 50 microgram per cubic metre of air, surpassing the Indian standard for PM2.5 (40 microgram per cubic metre). This level of pollution would place Darjeeling on par with many polluted cities in the Indo-Gangetic Plain region and other urban areas of India,” Dr. Ghosh added. Monami Dutta of the Bose Institute also contributed to the study which was published in the journal “Atmospheric Environment”.

Contributing factors

There are several factors that contribute to the ultrafine particulate matter PM1 in both summers and winters in the hills. The study said that during the summer, vehicular emissions from tourist activities contributed 33%, while biomass burning from roadside eateries accounted for 21%. Dust transport from the Indo-Gangetic plain, coal combustion from eateries, domestic use, and the Toy Train, as well as secondary sources, also played a role.

In winter, biomass burning for low-temperature requirements contributed 27%, vehicular emissions constituted 25%, and coal combustion accounted for 20%, with dust and secondary sources contributing to the remainder. “Vehicular emissions alone accounted for over 90% of PM10 in summer, while biomass burning contributed more than 80% in winter,” the study pointed out.

Researchers said that the findings raised concerns about uncontrolled tourist influx, unplanned urbanisation, unauthorised land use, biomass and combustion activities, and the use of old vehicles and diesel-driven generator sets, in Darjeeling.

A press statement issued by Asar Social Impact Advisors as a part of a project under the ‘Simplifying Science’ pointed out that the National Clean Air Program (NCAP), initiated by the Government of India, aimed to mitigate air pollution in 131 cities across the country, focusing on aerosols, PM2.5, and PM10 but certain regions with polluted urban environments, including Darjeeling, should also be brought under such a mission or at least draw attention of the policy makers.