Impact of the Suspension of a Metallurgical Complex: SO₂ Analysis and Vegetation Restoration Through Remote Sensing

Abstract

Sulfur dioxide (SO₂) pollution significantly threatens ecosystems and public health, particularly in highly industrialized regions. This study evaluates the impact of suspending activities at the La Oroya Metallurgical Complex (CMLO, by its Spanish acronym), one of the most relevant historical sources of SO₂ pollution in the Central Andes of Peru. Using remote sensing data (MODIS and Ozone Monitoring Instrument [OMI]), temporal and spatial trends in the normalized difference vegetation index (NDVI) and SO₂ concentrations were analyzed from 2000 to 2019. The results show an average reduction of 82.18% in SO₂ after the CMLO was stopped, accompanied by a significant positive increase in the NDVI trend (p < 0.05), which shows a recovery of the vegetation in surrounding areas. Vegetation regeneration showed marked spatial patterns to the southwest and southeast of the CMLO, influenced by the dispersion of pollutants through prevailing winds. However, the moderate relationship between the decrease in SO₂ and NDVI (R² = 0.10) suggests the influence of additional factors, such as the historical accumulation of heavy metals, water scarcity, and the specific characteristics of high Andean soils and vegetation.