16. Air Pollution Episode Analysis and Qualitative Evaluation of Proposed Control Measures in Delhi City

Increasing air pollution levels in Delhi city is a major concern for regulators and stakeholders because of its associated critical and acute health impacts on human beings. During the onset of winter every year (in the months of October and November), people of Delhi were facing an increased level of pollutant concentrations from the last few years. The present study is an attempt to analyze the increased air pollution level episodic situation that occurred during 5–6th November 2016 in Delhi city. Four differently located air monitoring stations data on Air Quality Index, pollutant concentration, and meteorology from 25th October to 15th November 2016 are considered for the present analysis. The results indicate that PM_2.5 concentrations exceeded 12–14 times whereas PM₁₀ levels exceeded 8–17 times of NAAQS values of 60 µg/m³ and 100 µg/m³, respectively on 5–6th November 2016. The meteorological conditions were found worst for pollution dispersion on these two days which may be one of the reasons for high air pollution occurrence. However, NO_x and SO₂ concentration peaks were observed during Diwali days (Oct. 29–31, 2016). Critical analysis of the situation indicates that local sources are influencing the pollutant concentration significantly at the monitoring stations. Further, the qualitative evaluation of the graded response action plan (GRAP) indicates that the efficacy of a particular mitigation action on pollution reduction shall vary from site to site. Hence, in order to improve air quality in different zones, more emphasis needs to be given on regulating local activities as per suggested actions in addition to the regional level action plans.