More of the Country Is Breathing Smoke

Number of Americans living in a county with at least one day when wildfire smoke alone exceeded the federal daily limit for PM2.5 of 35 µg/m³.

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The federal 24-hour standard for fine particles is 35 µg/m³. These figures count pollution from wildfire smoke only; ordinary sources push actual readings higher still. Author's calculations from Childs et al., Environmental Science & Technology (2022), version 2.0 data through 2023.