LAGGED ASSOCIATION BETWEEN PUNJAB CROP-RESIDUE BURNING AND PM 2.5 POLLUTION IN DELHI-NCR: A NINE-YEAR TIME-SERIES ANALYSIS

Background: Crop residue burning in Punjab, a post harvest agricultural practice, has long been implicated as a significant driver of catastrophic air-quality deterioration in Delhi-NCR during October -November. However, the precise temporal lag and the role of meteorological confounders remain insufficiently clarified in the existing literature. Methods: We assembled a daily time-series dataset spanning nine harvest seasons (2015 - 2024; n = 486 station- days) that integrates satellite-derived Punjab fire counts from NASA FIRMS, ground-level PM2.5 observations from CPCB monitoring stations, and ERA5-Land daily meteorological covariates (wind speed at 850 hPa, planetary boundary layer height, temperature, relative humidity, and rainfall) to control for atmospheric confounding. Cross-correlation, multivariable distributed-lag regression models, and Cochrane-Orcutt autocorrelation correction were employed to characterise the spatiotemporal relationship between burning activity and urban particulate pollution.