Analysis of spatiotemporal distribution of air quality index (AQI) in the state of West Bengal, India from 2016 to 2021

Abstract

The ambient air quality is progressively declining, especially in emerging countries, due to increased urbanization, high demands of energy, and industrialization. High risks to human health and environmental degradation are associated with air pollution. The analysis of the Air Quality Index (AQI) serves as a valuable tool for simplifying the communication of air quality in a specific region, making it easily comprehensible to the general public. The United States Environmental Protection Agency (USEPA) and Indian air quality regulations recommend mathematical functions to compute sub-indices for calculating the AQI. The main objectives of this study were to evaluate the AQI status from a different point of view (monthly, seasonal, and annual variations and association of AQI with meteorological factors) and estimate the future AQI. The monthly AQI values in West Bengal vary from “Satisfactory to Moderate” level from 2016 to 2021. In district-wise, the highest AQI was observed in Kolkata (189), Bardhaman (178), and Murshidabad (167) in the year 2016; Kolkata (180), Bardhaman (155), and Howrah (155) in 2017; Howrah (180), Kolkata (179) and Hoogly (166) in 2018; Howrah (170), Kolkata (156) and Bardhaman (156) in 2019; Howrah (150), South 24 Parganas (137), and Kolkata (136) in 2020 and Howrah (161), Kolkata (139), and South 24 Parganas (139) in 2021 respectively in Winter season. The association between meteorological parameters, such as temperature (r = − 0.605, p < 0.001), relative humidity (r = − 0.647, p < 0.001), and precipitation (r = − 0.821, p < 0.001) and AQI shows a significant strong negative correlation (p < 0.05). In addition, the relative influence of temperature, precipitation, and relative humidity was 53.13%, 36.69%, and 10.18%, respectively, on AQI variation. Temperature plays a significant role in association with AQI distribution in the atmosphere than RH and precipitation. The distribution of AQI in the whole state of West Bengal showed a higher AQI observed in the Southern part compared to the northern part of the state. The study's conclusions and recommendations can help stakeholders and policymakers’ to control and improve the deterioration of air quality caused by concerns about AQI and human health.