Seasonal dynamics and impacts of surface ozone pollution over Bhubaneswar

This study investigates surface ozone (O₃) dynamics in Bhubaneswar (2020-2024) using in situ observations, satellite retrievals, and model-based diagnostics to assess seasonal variability, precursor sensitivity, and related health and agricultural impacts. Compared with the 2010-2015 period, where winter daytime O₃ reached ~ 75 ppb, the 2020-2024 record shows moderated winter daytime peaks (~ 51 ppb) but significantly elevated monsoon baselines. Specifically, 24-h monsoon means rose to ~ 25 ppb from ~ 12-15 ppb a decade ago, reflecting a shift toward sustained annual O₃ levels. Despite declining seasonal peaks, the frequency of episodic exceedances and estimated crop yield losses has increased. Precursor sensitivity analysis reveals a VOC-limited regime in winter (35%), transitioning to NO_x-limited during pre-monsoon (34%) and post-monsoon (29%) periods, with mixed conditions during monsoon (28%). Health risk assessment via the maximum daily 8-h average (MDA8) indicates frequent exceedances of the 50 ppb threshold, particularly in winter and pre-monsoon, signifying chronic exposure risks. Agricultural indices (AOT40, M7, M12, and SUM60) suggest substantial yield losses in paddy and rabi crops, especially during high O₃ seasons. Comparisons with Delhi (2024) highlight contrasting O₃ formation regimes, where Delhi remains largely VOC-limited due to persistent NO_x saturation. The findings emphasize the need for season- and region-specific emission controls, enhanced VOC monitoring, and AI-driven forecasting to support adaptive air quality management in urbanizing eastern India.