Characterizing Ambient Fine Particulate Matter Pollution in Jordan: National Monitoring Evidence of Spatial Inequality, PM2.5 Hotspots, and Temporal Trends (2021–2024)

Ambient PM2.5 monitoring data provide evidence of location-specific pollution patterns, although uneven network coverage and incomplete station-level quality-assurance metadata constrain inference. We examined 69 annual reporting-code records available in Jordan during 2021–2024 and a balanced panel of 16 codes observed in all four years (64 code-year records). Balanced-panel annual means were 27.56, 30.53, 30.40, and 26.48 µg/m3, respectively; the four-point Mann–Kendall test did not detect a monotonic trend (p = 0.750; Sen’s slope = −0.25 µg/m3/year). Four monitoring locations met the relative upper-quartile hotspot threshold (33.71 µg/m3): Al-Yarmouk, Municipal Slaughterhouse/Industrial Area, Al-Hashemiteh Hall, and University Street/Sweileh. An exact permutation-based Kruskal–Wallis comparison of sampled governorate site means indicated heterogeneity (H = 9.56, exact p = 0.00993), also observed when either Sahab reporting code was omitted (exact p = 0.01316 and 0.01730). However, the highly unequal and sparse governorate samples preclude population-level inference. Industrial (n = 6) and non-industrial urban/traffic/background (n = 10) site means did not differ significantly (Mann–Whitney U = 29.0, p = 0.958). These data do not establish a national long-term trend, representative population exposure, or pollution-source attribution.