Assam's silent air crisis: Beyond cities, a state choking on neglect

0ver the 23-year period from 2000 to 2022, Assam recorded a State-level mean PM2.5 concentration of 49.5 µg/m²-well above the national ambient air quality standard (NAAQS) of 40 ug/m³. Satellite-based data developed by IIT Delhi reveals a clear west-to-east gradient in PM2.5 levels, with higher concentrations (over 60 µg/m²³) observed in the western and southwestern districts, especially near State borders.

Conversely, northeastern districts often report lower levels, typically below 40 µg/m³. This variation is shaped by industrial proximity, cross-border pollution, vehicular emissions, and meteorological patterns, as outlined in a draft report by Climate Trends, PCBA, and ASTEC. Air quality management in Assam is hindered by an urban-centric monitoring network, leaving rural and peri-urban areas largely unrepresented in official data.

The report recommends a phased expansion of CAAQMS to ensure that every district, especially hotspots like Digboi, Bokajan, and the Guwahati-Byrnihat corridor, is covered. Low-cost sensors can supplement this network in rural and forest-fringe areas. Additionally, integrating ground-level data with satellite observations, meteorological inputs, and fire-detection systems into a public air-quality dashboard could enhance data-driven policymaking.

Under the National Clean Air Programme, Assam is listed as a "non-attainment" State, expected to reduce PM2.5 and PM10 levels by 20-30 per cent by 2027 from 2017 haselines. However, implementation remains weak due to fragmented responsibilities, insufficient funding, and a lack of institutional coordination.

Despite relatively low industrial activity, Assam faces a complex mix of pollution sources, including traditional biomass use in rural areas, seasonal crop residue burning, municipal waste burning, and emissions from oil refineries, cement plants, and brick kilns.

Vehicular emissions have emerged as a dominant source of pollution. Guwahati, for instance, is grappling with rapid motorisation, congestion, and outdated vehicles. Diesel-run buses, autos, and river ferries dominate transport in towns like Dibrugarh and Silchar, while freight traffic along the Guwahati-Byrnihat corridor contributes significantly to emissions.

The lack of public transport infrastructure further exacerbates the problem. Assam's geographical features, such as the Brahmaputra Valley's bowl-like shape, hinder pollutant dispersion. Winter inversions trap air pollutants near the ground, while floods and biomass decomposition during post-flood recovery contribute to secondary pollution.

Climate change is expected to worsen these dynamics through increased forest fires and dust events. Assam's air pollution crisis is a reflection of both structural deficiencies and overlooked rural realities. While industrial emissions and vehicular growth are major contributors, the State's heavy reliance on biomass, weak enforcement, and limited monitoring have allowed pollution to grow largely unchecked.

A comprehensive and inclusive approach-combining scientific monitoring, clean technology adoption, and community engagement - is urgently needed. Strengthening governance, securing dedicated funding, and fostering cross-sectoral coordination will be key to ensuring Assam moves from pollution control rhetoric to measurable, equitable air quality improvements.