India’s air pollution crisis is deepening as small towns catch up with metros

Air pollution remains a major concern across Indian cities, with significant variations in air quality levels between large metropolitan areas and smaller cities. A new and alarming trend has emerged—smaller cities, once considered relatively cleaner, are now experiencing dangerously high pollution levels.

Byrnihat, a small industrial town on the Assam-Meghalaya border, has emerged as India’s new pollution hotspot, surpassing even Delhi in annual PM2.5 levels. According to Central Pollution Control Board (CPCB) data, Byrnihat recorded an alarming 133.4 microgram per cubic metre (µg/m³), exceeding the national standard by a staggering 3.3 times. This marks a significant shift in India’s air pollution crisis, as smaller towns are now registering pollution levels once thought to be a problem only for metro cities.

The air quality in Byrnihat has deteriorated to such an extent that a drastic 70 per cent reduction in PM2.5 levels is required to meet the annual standard. In comparison, Delhi, which has long been in the spotlight for its hazardous air, recorded an annual average PM2.5 concentration of 104.9 µg/m³, reflecting a 4 per cent increase from the previous year’s 101 µg/m³. The consistent rise in pollution levels across cities highlights the deep-rooted air quality crisis that extends beyond the metros.

Other highly polluted cities include Gurugram (91.7 µg/m³), Sri Ganganagar (87.2 µg/m³), Faridabad (84.7 µg/m³), Greater Noida (83.6 µg/m³), and Muzaffarnagar (83.4 µg/m³). The data indicates that industrial belts and rapidly urbanising regions are bearing the brunt of escalating emissions. The air quality trends also suggest that smaller cities, previously overlooked in national air pollution discourse, are becoming critical zones requiring urgent intervention.

A recent IQAir report echoes these findings. While there are slight variations in numbers—with Byrnihat at 128.2 µg/m³ and Delhi at 108.3 µg/m³—the underlying message remains the same: India’s air pollution problem is expanding in scale and intensity, engulfing newer regions in a worsening crisis.

The most polluted cities in India, as highlighted in the recent air quality report released by IQAir alongside CPCB data, reveal alarming PM2.5 concentrations.

Amidst this bleak scenario, a handful of cities have managed to maintain relatively clean air. Gangtok, the capital of Sikkim, stands out as one of the cleanest cities in India, with a PM2.5 concentration of 13.8 µg/m³, Aizawl in Mizoram follows closely at 16 µg/m³, while Tirupur in Tamil Nadu records 14.8 µg/m³. These cities, largely located in India’s Northeast and Southern regions, benefit from a combination of lower industrial activity, higher forest cover, and effective local interventions to curb emissions.

The notion that air pollution is a “big city problem” is rapidly crumbling. The data clearly indicates that smaller towns and industrial hubs are now at the frontline of India’s air pollution crisis. The shifting pollution patterns underscore the need for stronger regulatory frameworks, improved monitoring networks, and aggressive mitigation measures. As smaller towns like Byrnihat emerge as pollution hotspots, the focus must extend beyond metro cities to ensure cleaner air for all. Without urgent intervention, air pollution will continue to be a silent killer, affecting millions across urban and semi-urban landscapes.