Long‑term trends and seasonal variability of particulate matter (PM10 and PM2.5) in Volta Redonda (RJ), Brazil: a 15‑year temporal analysis

Abstract

Air quality in Volta Redonda, Rio de Janeiro, Brazil, is influenced by industrial activities and meteorological conditions, but its temporal evolution and spatial variability require systematic assessment. This study evaluated PM₁₀ and PM_2.5 concentrations from 2010 to 2024, investigating temporal trends, spatial and seasonal differences, and their relationships with meteorological variables. The Mann–Kendall test and Theil–Sen estimator were applied to assess trends, Mann–Whitney tests to compare periods and seasons, Kruskal–Wallis tests to evaluate spatial differences, and Spearman correlations to assess meteorological relationships, complemented by pollution roses and concentration-weighted trajectory (CWT) analysis. Annual PM₁₀ concentrations exceeded the World Health Organization annual guideline of 15 µg m⁻³ at all stations and in all analyzed years, while PM_2.5 exceeded 5 µg m⁻³ in all years at the Volta Grande station. In 2024, 36% of PM₁₀ measurements exceeded the national standard of 35 µg m⁻³, with annual means of 44 ± 22 µg m⁻³ at Conforto and 44 ± 12 µg m⁻³ at Siderville. No significant long-term monotonic trends were identified for PM₁₀ or PM_2.5; for PM_2.5, the Theil–Sen slope was −0.346 µg m⁻³ year⁻¹ (p = 0.0866). Concentrations were higher in winter than in summer for PM₁₀ (p = 0.002) and PM_2.5 (p = 0.001), while PM₁₀ showed negative correlations with precipitation (r =  −0.66) and temperature (r =  −0.46). CWT analysis indicated potential contribution regions predominantly west and northwest of the receptor stations.