Tuticorin Air Quality Improves Noticeably After Sterlite Closure: TNPCB Data

Any air pollution monitor that does not record a decline in pollution even after all production and vehicular movement ceases has to be treated as suspect.

Chennai: On 5 December, 2019, the Times of India reported based on a Right to Information application that the air quality in Tuticorin, Tamil Nadu, hadn’t changed even after the city’s controversial Sterlite copper-smelting plant had been shut down.

However, air quality data from the National Air Monitoring Program for Tuticorin suggests exactly the opposite.

The Tamil Nadu Pollution Control Board (TNPCB) operates three air-quality monitors in Tuticorin as part of the Central Pollution Control Board’s national programme. All three monitors, including one located in the SIPCOT Industrial complex that houses the now-dormant Sterlite smelter, consistently recorded more days with healthy air quality indices (AQI) and fewer days with poor air quality between April 2018 and March 2019 (data sources split here, here and here) relative to the same period in 2017.

The AQI is a pollution index calculated as an aggregate of several pollution parameters, including the amounts of sulphur dioxide, nitrogen dioxide, ozone, ammonia and particulate matter (such as, but not limited to, dust). Under the National Air Monitoring Program, the TNPCB is required to analyse at least two air samples every week, which comes to 104 samples in a year from each location for the above parameters.

The conclusion of the newspaper article appears to be based on data generated by an air-quality monitoring station in Fisheries College, and claim that the station is “closest to the now defunct smelter.” That is incorrect. The SIPCOT monitor, located 2 km away, is the closest to the smelter. Fisheries College is 5.5 km away, and is in fact not part of CPCB’s national monitoring program. A long-serving district environmental engineer from TNPCB also said that he was not aware of a monitoring station in Fisheries College.

The AQI data recorded at the SIPCOT station shows that the number of unhealthy-air days declined from 56% in the year ending March 2018, when the Sterlite unit was still operating, to 27% in 2018-19, the year after the unit was closed. In the same period, the number of days with ‘acceptable air’ increased from 44% to 73% after the unit was closed.

People living in villages near the plant provided anecdotal confirmation. A. Dharmaraj, an elderly resident of Therku Veerapandiapuram, said, “There is hardly any dust now.” Others from Meelavittan and Pandarampatti say they are now able to sleep outdoors and on the terrace without feeling irritated or sick.

Indeed, it is hard to imagine the Sterlite unit’s closure didn’t affect air quality. Consider the details available in Sterlite’s own environmental impact assessment report: every day the factory operates, 6,515 vehicles – including 3,235 two- and three-wheelers, 1,214 cars and 2,066 trucks – and heavy vehicles enter and exit the factory gate. Bad roads and the absence of a healthy greenbelt worsen the pollution as resuspended road dust piles on the emissions from these vehicles.

In addition, the smelter used to burn more than 5,000 tonnes of copper concentrate, 94 tonnes of furnace oil, three tonnes of diesel and 40 tonnes of coking coal every day, and emitted the byproducts through ill-designed chimney stacks. (The Wire has reported on these issues at length and may be read here.)

All these, together with the discharge of effluents laden with heavy metals and fluorides, contribute to particulate, gaseous and soil/water pollution. Sterlite’s argument that sulphur dioxide levels have remained unchanged and changes in dust or particulate matter levels have no relation to the company’s operations don’t hold any water. Sulphur dioxide is a major precursor to ambient PM2.5.

Any air pollution monitor that does not record a decline in pollution even after all production and vehicular movement ceases has to be treated as suspect. In this case, however, the SIPCOT monitor has rightly registered an improvement in the air quality.

The following AQI scores correspond to varying levels of impact (source):

CPCB air quality index chart

The AQI data from April 2017 to March 2018 and April 2018 to March 2019 has been tabulated below:

Nityanand Jayaraman is a Chennai-based writer and social activist who has been active in the people’s struggle against Vedanta’s pollution in Tuticorin.