Interpretation of air quality data using an air quality index for the city of Kanpur, India

Abstract

An air quality index (AQI) is proposed for the City of Kanpur, India, for simplified public information and data interpretation. A maximum operator concept is used to determine the overall AQI; maximum value of sub-indices (of each pollutant) is taken as the overall AQI. The mathematical functions for calculating sub-indices are proposed based on health criteria of the USEPA and Indian air quality standards. The pollutants included in the AQI are: SO2, SPM (suspended particulate matter), O3, NO2, PM10 (particulate matter with a diameter of 10 μm or less), and CO. The investigations into data interpretation using the AQI for Kanpur city have shown that air quality worsens (very poor to severe) in winter months and also during the early summer months (March, April, and part of May). These months are characterized by dusty winds resulting in high SPM. The air quality generally improves in monsoon and post-monsoon period (good to moderate) as rain washes out the pollutants. Over 95% of the time, sub-index values corresponding to SPM levels were responsible for overall AQI. Key words: air quality index, air quality data interpretation, Kanpur, India.