CONUS-PM1(V1)
PM1 (Submicron Particulate Matter) — Contiguous USA, 1998–2022
We estimate biweekly, gapless ambient submicron particulate matter (PM1) concentrations and their associated uncertainties at 1 km² resolution across the contiguous United States over the 25-year period 1998–2022. PM1 estimates are derived from hybrid PM2.5 chemical composition estimates (built from satellite aerosol retrievals, GEOS-Chem chemical transport modeling, and ground-based monitoring, see https://www.satpm.org/v6-na-01) by applying component-specific submicron mass fractions. These fractions are constrained by observations for four major PM2.5 components (sulfate, ammonium, nitrate, and organic matter) and by established scientific understanding for the remaining components (black carbon, dust, and sea salt). The resulting biweekly PM1 estimates are highly consistent with independent ground-based PM1 measurements (slope: 0.97, R²: 0.78). This dataset is intended to fill a long-standing gap in long-term PM1 data for the USA, enabling future studies of the health effects of PM1 exposure alongside the extensive existing PM2.5 record.
Reference:
Li C, Martin RV, van Donkelaar A, Jimenez JL, Barrette C, Turner JR, Liu X, Rowe M, Hanley T, Meng J, Yu W, Thurston GD. Estimates of submicron particulate matter (PM1) concentrations for 1998–2022 across the contiguous United States. Lancet Planet Health. 2025;9(6):e491–e502. DOI: 10.1016/S2542-5196(25)00094-4
Scientific Datasets:
Annual and biweekly datasets are provided in NetCDF [.nc] format. Gridded files use the WGS84 projection and cover the contiguous United States (CONUS).
Note that these estimates are primarily intended to aid in large-scale studies. Annual and coarse-resolution averages correspond to a simple mean of within-grid values. Gridded datasets are provided to allow users to agglomerate data as best meets their particular needs. The datasets are gridded at the finest resolution of the information sources that were incorporated, but are unlikely to fully resolve PM₁ gradients at the gridded resolution due to the influence of information sources at coarser resolution.
Annual mean PM₁ [µg/m³], 1998–2023 (CONUS.PM1.YYYY.V1.nc) and biweekly mean PM₁ [µg/m³] (CONUS.PM1.YYYYDDD–YYYYDDD.V1.nc, 14-day periods):
[https://wustl.box.com/s/913racixh7b5xmyaeagl68hw87y0pva1]
CONUS PM₁ V1 is licensed under CC BY 4.0.
These data were developed under NIH R01 ES035468-01. Users are welcome to contact Chi Li, Randall Martin, and George Thurston to collaborate on the application and interpretation of these data.