Structural Shifts in Urban Air Pollution Patterns in Trinidad After COVID-19: Evidence from Diurnal and Weekday/Weekend PM Profiles, 2022-2024

The COVID-19 pandemic temporarily reduced air pollution by disrupting human mobility. This study tests whether particulate pollution patterns in Trinidad and Tobago underwent lasting structural change during the post-pandemic period 2022-2024. We analyse continuous PM₂.₅ and PM₁₀ observations from four Environmental Management Authority monitoring sites representing distinct source environments: urban Port of Spain, industrial Point Lisas, suburban Arima, and mixed-use San Fernando. Hourly median diurnal profiles were computed by site and year and stratified by weekdays versus weekends. We then derived diagnostics of morning peak intensity, midday dispersion depth, nighttime baseline, and weekday/weekend contrast, and assessed interannual changes in variability using Levene’s tests. Results indicate a rebound toward pre-COVID dynamics by 2024. Urban sites exhibit sharper morning rush-hour peaks and deeper midday lulls; in Port of Spain, 7-8 AM PM₂.₅ medians increase from ~15 µg/m³ (2022) to ~20 µg/m³ (2024). Nighttime baselines rise modestly (~1-3 µg/m³), and weekday PM₂.₅ becomes ~20-30% higher than weekends. Point Lisas maintains a high, weakly varying baseline, while Arima and San Fernando show moderately intensifying morning peaks. Overall, post-pandemic improvements appear transient, supporting targeted transport and industrial emission controls.