About the PM2.5 Design Value Map

2023–2025 Annual PM2.5 Design Values

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Purpose

This interactive map displays annual fine particulate matter (PM2.5) design values at air quality monitoring sites across the contiguous United States. It highlights locations with design values exceeding the revised 2024 annual PM2.5 National Ambient Air Quality Standard (NAAQS) of 9.0 micrograms per cubic meter (µg/m³).

The map is intended to increase awareness among prescribed fire practitioners in the National Forest System of areas where monitored annual PM2.5 concentrations exceed or approach the standard. It also displays preliminary nonattainment reference areas and National Forest administrative boundaries to provide geographic context.

PM2.5 Design Values

Monitor values represent valid annual PM2.5 design values for the 2023–2025 monitoring period.

The revised annual PM2.5 National Ambient Air Quality Standard (NAAQS), established in 2024, is 9.0 µg/m³.

Nonattainment Areas (Preliminary)

The map includes selected EPA nonattainment and maintenance area polygons associated with the 2012 annual PM2.5 standard, filtered to areas with reported design values greater than 9.0 µg/m³. These areas provide geographic context for locations with elevated annual PM₂.₅ concentrations but should not be interpreted as a complete delineation of areas potentially exceeding the revised standard.

These polygons are provided for geographic reference only. They do not represent official nonattainment designations under the revised 2024 annual PM2.5 standard.

Data Sources

Limitations

The map is intended for informational and exploratory use. Design values are historical monitoring summaries, not real-time air quality measurements or forecasts.

Monitor-level exceedances do not independently establish an area's regulatory attainment status.