Human health risk as a basis for prioritizing air quality monitoring stations in a megacity: a case study

This paper presents an objective methodology for determining the optimum number of ambient air quality stations in a monitoring networks based on human health risk (HHR). The case study is related to HHRs in terms of mortality and morbidity (hospital admission) due to adverse effects of air pollution in 41 wards in Delhi in India, which were evaluated using Ri-MAP model developed by the World Health Organization (WHO). By adopting the World Health Organization (WHO) guideline concentrations of the air pollutants total suspended particles (TSP) or its surrogate, sulfur dioxide (SO2) and nitrogen dioxide (NO2), concentration-response relationships and a population attributable-risk proportion concept are applied. It was found that an average total mortality was 1150 [631–1852 at 95% confidence interval (CI)], cardiovascular mortality was 450 (440–665 at 95% CI), respiratory mortality was 170 (96–288 at 95% CI), and chronic obstructive pulmonary disease (COPD) morbidity was 176 (2–333 at 95% CI) for every one million population in Delhi according to 2008 population statistics. There were 20 wards which had mortality and morbidity higher than the average. It may be concluded that pollution control authorities need to monitor air quality in these 20 identified locations having high health risk more rigorously. From the result, it was also seen that the excess number of mortality and morbidity in Delhi was basically due to particulate matter (PM) than due to gaseous pollutants. Hence, the pollution control authorities in Delhi urgently need proper management policy to improve ambient air quality in terms of TSP levels.