How the Aravallis Shape Delhi-NCR’s Air Quality—and Why Protecting India’s Oldest Mountain Range Matters | Explained
As Delhi-NCR continues to battle severe air pollution, renewed attention has turned to the Aravalli range—India’s oldest mountain system—and its crucial role in regulating air quality, climate, and water security in north India. Recent protests by environmental groups and political parties have brought the Aravallis back into national focus, particularly after a new legal definition adopted by the Supreme Court raised concerns about the future protection of large parts of the range.
Context: Why the Aravallis Are Back in the Spotlight
Environmentalists, citizen groups such as People for Aravallis, scientists, and opposition parties including the Congress and Samajwadi Party have expressed concern over a recent reclassification of the Aravalli Hills. They argue that a height-based definition could leave over 90 percent of the range’s low-lying ridges, scrublands, slopes, and foothills without strong legal protection.
Critics warn that this could pave the way for expanded mining, real estate development, and unchecked urbanisation—causing irreversible ecological damage and worsening air pollution, water scarcity, and desertification across north India.
What Is the Aravalli Hills Controversy?
In November 2025, the Supreme Court accepted a uniform legal definition of the Aravalli Hills and Aravalli Range based on recommendations from a committee led by the Ministry of Environment, Forest and Climate Change. Under this definition, an “Aravalli Hill” is a landform rising at least 100 metres above its surrounding terrain, while an “Aravalli Range” consists of two or more such hills located within 500 metres of each other.
Union Environment Minister Bhupender Yadav has assured that the government remains committed to protecting the Aravallis. He stated that the reclassification aims to bring uniformity in environmental law enforcement, as earlier each state followed different criteria, often allowing mining activities. According to the government, only 0.19 percent of the total Aravalli area—around 277.89 square kilometres out of 1.44 lakh square kilometres—has been opened to mining, with no new mines approved. The minister also said the definition was made stricter to safeguard the proposed Green Aravalli Wall project.
How Do the Aravallis Influence Delhi’s Air Pollution?
Climate scientists underline that the Aravallis act as a natural barrier that restricts the movement of dust and sand from the Thar Desert towards the Indo-Gangetic plains. The range also influences regional wind patterns, reducing the volume of dust-laden winds reaching Delhi-NCR, particularly during dry and windy months.
Dr Manish Kumar, a climate scientist and director of the Sustainable Bharat Foundation, has noted that degradation of the Aravalli landscape can significantly increase dust loading towards Delhi-NCR. Loss of vegetation, mining activity, and land disturbance weaken this natural shield, contributing to higher levels of particulate matter such as PM2.5 and PM10.
Why Are Environmentalists Concerned?
Environmentalists argue that ecological value cannot be determined by elevation alone. The Aravalli ecosystem includes forests, slopes, groundwater recharge zones, and low hill systems that play a vital functional role in climate regulation and water security. They fear that implementation of the new definition may overlook these ecologically critical areas unless scientific mapping and comprehensive management plans are strictly enforced.
Why Delhi-NCR’s Ecological Balance Matters
Delhi-NCR’s environmental health is deeply connected to surrounding natural systems such as the Aravallis, forest corridors, and recharge zones. These systems moderate temperatures, support groundwater replenishment, and reduce the environmental stress caused by rapid urbanisation. Their degradation could intensify long-term risks including extreme heat, water shortages, and worsening air quality.
Climate Risks of Aravalli Degradation
The Aravallis help stabilise soil, sustain vegetation, and support aquifers. Their decline could increase the frequency of dust storms, intensify heatwaves, and reduce water availability—making the region more vulnerable to climate change impacts.
Why the Aravallis Matter to India
Stretching over 670 kilometres from Delhi through Haryana and Rajasthan to Gujarat, the Aravalli range is around two billion years old. With a highest peak of 1,722 metres at Guru Shikhar in Mount Abu, the range acts as a natural shield preventing the eastward spread of the Thar Desert into fertile regions of north India.
For Delhi-NCR—among the world’s most polluted regions—the Aravallis function as natural “green lungs,” trapping dust, absorbing pollutants, and aiding groundwater recharge for millions. Their protection also aligns with India’s commitments under the UN Convention to Combat Desertification.
Conclusion
While Delhi’s air pollution has multiple causes, experts agree that protecting surrounding natural buffers like the Aravallis is essential for long-term environmental resilience. The challenge now lies in ensuring that legal definitions translate into meaningful on-ground conservation.
Our Thoughts
The debate over the Aravallis is not merely about definitions or legal boundaries—it is about safeguarding a natural system that silently protects north India from desertification, pollution, and water stress. As Delhi-NCR searches for sustainable solutions to its air quality crisis, preserving the Aravallis must be viewed as a long-term investment in public health, climate resilience, and ecological balance. Effective protection will depend not just on policy assurances, but on science-driven implementation and vigilant oversight.
