IMPACT ASSESSMENT OF GRAP SCHEME IMPLEMENTATION DURING EXTREME POLLUTION EVENTS IN DELHI

Abstract

The high level of air pollution in the megacity of Delhi is extremely concerning and requires committed, rigorous efforts to reduce it to achieve the specified standards. The study evaluated the impact of the Graded Response Action Plan (GRAP) on air quality in Delhi, India, focusing on changes before, during, and after its implementation across various zones. Data was collected from 41 monitoring stations in Delhi, divided into two phases (2022-2023 and 2023-2024), and included concentrations of key pollutants. The data was analyzed to illustrate pollutant concentration changes across different GRAP stages within specified zones. The study found that all zones experienced increased pollutant concentrations during Phase 1, while Phase 2 showed a decreasing trend, indicating the effectiveness of Phase 2 GRAP interventions. The CO concentrations across all zones and phases, maintain stable levels. However, NH3 and NOx levels increased in Phase 1, while O3 and SO2 levels fluctuated. PM10 and PM2.5 levels also increased in both phases. In Phase 1, NO2 concentrations increased except in the east zone, while other pollutants (NOx, NO, PM2.5, and PM10) showed an increasing trend. In Phase 2, NH3 concentrations increased except in the north, south, and east zones, while NOx, NO2, NO, PM2.5, and PM10 concentrations increased except in the west and central zones. On a zone basis, the study reveals that the north, south, and west zones of Delhi have the most significant increasing trends in pollutants in Phase 1 and Phase 2, respectively. The east zone shows the most consistent decreasing trends in Phase 1 and Phase 2. Compared with the standard, PM2.5 and PM10 consistently exceeded the National Ambient Air Quality Standards (NAAQS) limits in both Phase 1 and 2, while NH3, O3, SO2, and CO remained within acceptable limits. However, NOx, NO2, and NO exhibited fluctuating concentrations, suggesting that more measures are needed for effective air v pollution control. The study recommends enhancing GRAP measures, particularly targeting high-emission zones like North and South Delhi, and incorporating additional interventions to ensure more significant reductions in pollutant levels to meet air quality standards.