A CORRESPONDENT
DIGBOI: Panic and outrage gripped Digboi in Assam's Tinsukia district on Tuesday afternoon after a dense cloud of gas billowed from a towering flare chimney at the Indian Oil Corporation Limited's Assam Oil Division (AOD) refinery, spreading across parts of the township in full public view. The dark plume, visible from several kilometres away, cast a haze over nearby residential areas and triggered fears of possible toxic exposure among residents.
Eyewitnesses described the emission as unusually thick and sustained, drifting slowly under calm atmospheric conditions. A strong, pungent odour reportedly accompanied the release, with several residents complaining of throat irritation, burning eyes, coughing, dizziness and breathing discomfort. The scale, density and duration of the discharge in broad daylight have raised concerns about operational safeguards and whether emission control systems were functioning effectively at the time.
Environmental observers note that refinery flare gases may contain sulphur dioxide (SO2), nitrogen oxides (NO2), fine particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs) such as benzene, and traces of carbon monoxide (CO) or hydrogen sulphide (H?S), depending on processing conditions. Exposure to elevated levels of these pollutants can cause respiratory distress, aggravate asthma, inflame airways and, in prolonged cases, increase the risk of cardiovascular disease. Benzene is also recognized as a carcinogen.
Members of the Digboi Journalists' Union, seeking an independent technical assessment, contacted experts from public sector refineries outside the state. According to them, while flaring is a recognized safety mechanism to burn off excess gases, dense and visibly heavy plumes in broad daylight are not typical under stable operating conditions. They noted that modern refineries are equipped with vapour recovery systems, flare gas recovery units and advanced emission control technologies designed to minimize visible smoke and reduce pollutant discharge.
These experts stated that persistent dark emissions may indicate operational upset conditions, incomplete combustion, excess sulphur load or temporary malfunction of pollution control systems-situations that warrant transparent reporting and technical scrutiny. They emphasized that although flaring is routine, the intensity and visibility of emissions are key indicators of operational efficiency and environmental compliance, especially in populated areas.
Sources within the refinery said the incident prompted immediate internal coordination. When contacted, the General Manager (Human Resources), AOD, sought to allay public concern, stating, "Don't panic. The cloud of released gases will subside within half an hour, as informed by the Production group." AOD Corporate Communications echoed the advisory, maintaining that the situation was temporary and expected to normalize shortly.
Executive Director-cum-Refinery Head Rahul Prasant described the development as part of normal refinery operations. He explained that accumulated waste gases are periodically burnt and released through the flare chimney to maintain safe and efficient functioning. While acknowledging concerns over possible inhalation of contaminated gases, he reiterated that flaring is a standard and necessary component of refinery processes.
Under the Air (Prevention and Control of Pollution) Act, 1981, industrial units are required to operate pollution control systems and Continuous Emission Monitoring Systems (CEMS) to ensure that emissions of sulphur dioxide, nitrogen oxides, particulate matter and other pollutants remain within prescribed limits. In this regard, the oversight role of the Central Pollution Control Board and the Assam Pollution Control Board is crucial.
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