Study finds even remote Himalayan air is turning polluted

DST-institute researchers tracking reactive hydrocarbons in a high-altitude Himalayan town found a shift from clean to polluted air, driven by tourism, fuel use and vehicles — with a long-term benzene cancer risk.

What happened

• A study by researchers at the Aryabhatta Research Institute of Observational Sciences (ARIES), an autonomous institute of the Department of Science and Technology (DST), found that even pristine, remote Himalayan regions are no longer untouched by air pollution.
• Over 2022-2023, the team measured non-methane hydrocarbons (NMHCs) — reactive gases from fuel use, vehicles and human activity that drive ozone and secondary aerosols — at Munsyari, a high-altitude tourist destination in Uttarakhand.
• They observed seasonal patterns (lower NMHCs in winter and monsoon, higher in spring and autumn) and identified LPG/diesel use, vehicular emissions and local construction as the dominant contributors.
• Aromatic hydrocarbons such as benzene and xylene were found to strongly drive secondary pollutants like ozone; Munsyari's NMHC levels were higher than at Nainital but lower than urban centres like Haldwani and Delhi.
• While immediate health risks are low, long-term benzene exposure poses a cancer risk above safety limits — underscoring the need for sustained monitoring and clean-up in sensitive regions.

For Prelims

• ARIES: The Aryabhatta Research Institute of Observational Sciences, an autonomous institute of the DST at Nainital (Uttarakhand), works on astronomy, astrophysics and atmospheric sciences (it hosts the Devasthal optical telescope).
• Non-methane hydrocarbons (NMHCs): Volatile organic compounds (excluding methane) emitted from fuel combustion and vehicles; they are precursors of tropospheric ozone and secondary organic aerosols.
• Tropospheric (ground-level) ozone: A secondary pollutant and greenhouse gas formed when sunlight acts on NOx and VOCs — harmful to health and crops (unlike protective stratospheric ozone).
• Benzene: An aromatic VOC and known carcinogen; chronic exposure is linked to cancer, which is why ambient limits are set under India's National Ambient Air Quality Standards (NAAQS).
• Secondary vs primary pollutants: Primary pollutants are emitted directly (e.g. NOx); secondary pollutants (ozone, secondary aerosols) form in the atmosphere from precursors like NMHCs.
• Why remote sites matter: Pollution reaching pristine high-altitude sites signals long-range transport and local anthropogenic pressure (tourism), threatening fragile Himalayan ecosystems.
• Don't confuse: Ground-level (tropospheric) ozone is a harmful pollutant — not the protective stratospheric ozone layer; NMHCs are precursors, not the pollutant measured as the AQI's particulate matter.

For Mains

Syllabus: GS3.14 · GS1.12 · Linkage L2