Wildfire smoke breaks the environmental-justice mold: divergent distribution of smoke and background PM₂.₅ across the contiguous US, 2006–2020

This project analyzes how wildfire-smoke fine particulate matter (PM₂.₅) is distributed across U.S. communities compared with ordinary "background" pollution. Combining 15 years (2006–2020) of satellite-derived smoke estimates, total-PM₂.₅ data, Census demographics, and land cover for all 72,537 contiguous-U.S. census tracts, it finds that background pollution follows the well-documented environmental-justice pattern (higher exposure in more-nonwhite neighborhoods), whereas wildfire smoke does not, nationally it is roughly evenly distributed, and in the West it is borne disproportionately by whiter, rural, forested communities. Smoke's share of total PM₂.₅ rose from under 2% to about 11% over the period while exposure inequality grew, and the Western pattern is shown to be geographic (driven by regional forest cover and population density) rather than demographic. The archive includes all code, analysis-ready data tables, and figures needed to reproduce the results.