Assessment of Short-Term Air Quality Variations and Health Risk during Post-COVID Period using AQI Data

The COVID-19 pandemic and subsequent lockdowns led to unprecedented improvements in urban air quality; however, the post-COVID period has been marked by a gradual rebound in pollution levels. This study assesses short-term air quality variations and associated health risks during the post-COVID period using Air Quality Index (AQI) data for Bhubaneswar, India. Hourly and daily concentrations of major criteria pollutants (PM₂.₅, PM₁₀, NO₂, SO₂, CO, and O₃) were analysed to examine temporal trends, short-term pollution episodes, and seasonal variability. The results indicate that postCOVID air quality predominantly ranged from moderate to poor, with pronounced deterioration during the winter and premonsoon seasons and comparatively improved conditions during the monsoon period. Short-term high-pollution episodes were frequent and persistent, driven mainly by particulate matter, leading to elevated AQI values and increased exposure risk. Health risk assessment based on AQI categories and international guideline thresholds suggests a heightened risk of respiratory and cardiovascular effects during poor and very poor air quality conditions. Comparative analysis across pre-COVID, COVID lockdown, and post-COVID phases reveals a substantial pollution reduction during lockdowns followed by a significant rebound in the post-pandemic phase. The findings underscore the importance of real-time AQI monitoring, early warning systems, and season-specific mitigation strategies to protect public health and support sustainable urban air quality management in postpandemic cities.