From 2017 to 2024, PM₁₀ and PM₂.₅ concentrations were analyzed at four monitoring stations (Suceava, Iași, and Botoșani) using the Mann–Kendall test and Sen’s slope estimator to identify monotonic trends. Significant decreases in PM₁₀ were observed at BT-1 (−1.8 μg/m³/year) and IS-2 (−1.1 μg/m³/year), while SV-1 and SV-2 showed non-significant declines. For PM₂.₅, IS-2 exhibited a significant decreasing trend from 2017 to 2024 (−2.9 μg/m³/year), which was not significant over 2009–2024. Extended analysis of PM₂.₅ from 2009 to 2024 revealed clearer reductions in March–April at SV-1, whereas summer and autumn months showed no significant trends. At BT-1, PM₂.₅ concentrations were generally stable, except for a slight increase in June. Hourly PM₁₀ concentrations displayed distinct diurnal and seasonal patterns, with peaks in the morning and evening, lower values around midday, higher levels in late autumn and winter, and generally lower concentrations on weekends. In 2024, PM₁₀ and PM₂.₅ levels remained below the limits set for human health protection, but meeting the stricter standards of Directive (EU) 2024/2881 will require further efforts.