Digboi: A dense cloud of gases was released from a flare chimney of the Indian Oil Corporation Limited’s Assam Oil Division (AOD) Refinery in Digboi on Tuesday morning, covering parts of the township.
Residents reported mild throat irritation, eye discomfort, and breathing unease.
The plume, visible from several kilometres away, has raised questions about operational safeguards, emission control, and adherence to environmental standards.
Eyewitnesses described it as heavy and persistent, drifting over nearby residential areas. Many also noted a pungent odor accompanying the emission.
Executive Director-cum-Refinery Head Rahul Prasant said the release was part of normal refinery operations. “To maintain safe operations, accumulated waste gases are periodically burnt and released through the flare chimney,” he explained. He acknowledged public concern but stated that flaring is a standard procedure.
Experts from other public sector refineries noted that while flaring is a recognized safety mechanism, dense visible plumes in broad daylight are not ideal under normal operating conditions.
They highlighted that modern refineries use flare gas recovery systems and other emission control technologies to minimize smoke and pollutant discharge. Persistent or dark emissions may indicate temporary operational issues, incomplete combustion, or high sulfur content, which require monitoring.
Refinery flare gases can include sulfur dioxide (SO), nitrogen oxides (NO), particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs) such as benzene, and traces of carbon monoxide (CO) or hydrogen sulfide (HS), depending on processing conditions. Short-term exposure can cause coughing, nausea, dizziness, chest discomfort, and headaches.
Sources said AOD immediately coordinated internally following the gas release. The General Manager (HR) stated, “Don’t panic. Process the requirements. The cloud of released gases will subside within half an hour, as informed by the Production group,” indicating that the Production group had conveyed its technical assessment and that the situation was expected to normalize shortly.
AOD Corporate Communication reiterated the advisory, stating, “Not to panic. Process requirements. The situation will come down within half an hour, as informed by the Production group,” reaffirming that the assessment indicated the condition was temporary and expected to stabilize quickly.
Environmental observers stressed that even routine flaring must comply with statutory emission standards under the Air (Prevention and Control of Pollution) Act, 1981. Refineries are required to operate pollution control systems and Continuous Emission Monitoring Systems (CEMS) to ensure emissions remain within prescribed limits.
The Central Pollution Control Board (CPCB) and the Assam Pollution Control Board (APCB) are responsible for verifying stack emissions, conducting inspections, monitoring ambient air quality, and taking enforcement action if standards are breached.
While refinery authorities maintain that the release was routine and temporary, the visibility of the plume and reports of public discomfort have prompted calls for disclosure of emission data and independent verification to ensure compliance with environmental and public health norms.