Description: Particulate matter conditions use PM₂.₅ and PM₁₀ concentrations. Condition categories (good, fair, poor) are based on the Environmental Protection Agency's human health-based Air Quality Index breakpoints and the most conservative of the measured particulate metrics. Metrics considered include the 3-year average of the weighted annual mean PM₂.₅ concentration, 98th percentile 24-hour PM₂.₅ concentration, and 2nd maximum 24-hour PM₁₀ concentration. See NPS air quality analysis methods for more information: https://www.nps.gov/articles/air-analysis-methods-latest.htm.