This study presents the first quantitative reconstruction of long-term changes in particulate matter (PM) abundance, elemental compositions, and sources using a combination of microscopic, elemental, and isotopic methods in archived biomonitors. We compared two sets of deciduous leaves collected from a park near a steel plant in Middletown, Ohio, in 1961 and 2022. Additionally, a set of lichen samples collected from Middletown underwent the same elemental and isotopic analysis as the leaf samples to better understand time-integrated PM sources in the region. Microscopic investigations revealed that the average amount of PM retained on the unit surface area of the 1961 leaves was 17 times higher than that of the 2022 leaves. Pb isotopes indicated that historical average PM masses originating from glacial till, the steel plant, gasoline, and fly ash were 533 ± 139, 343 ± 36, 435 ± 130, and 139 ± 14 mg m−2 respectively, while the corresponding values for the contemporary sources were 30 ± 6, 23 ± 3, 17 ± 2, and 12 ± 1 mg m−2. This suggests a shift in the primary anthropogenic source of PM from gasoline in 1961 to the steel plant in 2022, likely due to the phase-out of leaded gasoline. Elemental analysis revealed that PM emissions from the plant in the 1960s were 15 times higher and contained elevated concentrations of a wider range of elements compared to contemporary leaves. Further, lichen samples (estimated to date back to the late1980s to late 1990s) exhibited significantly elevated concentrations of Al, Cr, Fe, and V associated with steel plant emissions, with the highest anthropogenic relative contribution of PM originating from the steel plant, indicating the high impact of steel plant emissions prior to implementation of pollution control measures in 2006. Overall, these findings underscore that despite the significant decline in PM emissions observed over the last 60 years, the environmental impact of the steel plant continues. Keywords: Archived biomonitors; SEM/EDS; Pb isotopes; PM; Historical steel plant emissions; Temporal trends in air pollution.