While major metros in northern India choked under a blanket of toxic smog, the hill stations of the Northeast offered a breath of fresh air. Over two days this week, Shillong emerged as the clean air capital of India, recording the country's lowest Air Quality Index (AQI) levels. It was joined by Aizawl, with both cities firmly in the 'good' category, showcasing a stark national contrast.
A Tale of Two Indias: Pristine Hills vs. Polluted Plains
The difference in air quality was dramatic. Delhi NCR's AQI levels, fluctuating between 'very poor' and 'severe,' were nearly three times higher than the worst readings from the Northeast. On Monday, Shillong registered an exceptionally low, ozone-driven AQI of just 12. Aizawl, driven by PM2.5 particles, recorded a healthy 38. The clean air performance became even more impressive on Tuesday, as Shillong's AQI dipped further to an astonishing 9, with Aizawl holding steady at 38.
This pristine air is attributed to the region's natural advantages: higher altitude, extensive forest cover, and limited industrial activity. It stands in sharp relief to the severe pollution in Delhi NCR and even the 'moderate' air quality witnessed in Mumbai and Kolkata during the same period.
Not All Rosy in the Northeast: The Rise of 'Moderate' Pollution
However, the air quality picture across the Northeast was not uniformly bright. The region breathed two different kinds of air. While the highland cities enjoyed crisp, clean skies, several urban corridors showed signs of creeping particulate pollution.
On Monday, cities like Agartala (72), Kohima (74), Silchar (54), and Sivasagar (60) fell into the 'satisfactory' range. Their pollution was linked to dust, localized combustion, and mixed transport-industrial activities, rather than acute smog. The pressure points emerged in the 'moderate' category. This tier included Guwahati at 121, Nalbari at 156, Naharlagun at 181, Nagaon at 109, and Byrnihat at 158. These readings were dominated by fine particulates (PM2.5 and PM10), suggesting a mix of winter inversion, vehicular emissions, construction dust, and biomass burning.
PM2.5: A Persistent Health Concern
The situation tightened further on Tuesday. While some 'satisfactory' cities held steady, the 'moderate' cluster intensified in places. Guwahati's AQI rose to 151, Nalbari to 153, and Byrnihat to 162. Naharlagun improved slightly to 161 from 181, but remained in the moderate band. Nagaon increased to 115.
A critical concern is that the pollutant mix remained heavily skewed towards PM2.5, a fine particulate matter linked to long-term cardiopulmonary risks even at 'moderate' levels. Experts highlighted that cities like Guwahati, Nalbari, and Naharlagun are now showing this worrying trend. Notably, Silchar's dominant pollutant shifted from PM10 to PM2.5, indicating that finer, more harmful particles were becoming more influential under cooler, stable atmospheric conditions.
Environmental analysts caution that Shillong's exemplary readings serve as a national benchmark, proving what is possible when urban growth is balanced with ecological preservation. However, the looming challenge for the Northeast is to protect this natural advantage from being eroded by the pressures of rapid urbanization and development that have plagued other parts of the country.
