+Indicator Methodology
Data processing begins with the acquisition of daily PM2.5 measurements (parameter code
“88101”) and additional site-specific metadata (e.g., latitude, longitude) from the AQS Data Mart. Monitors
meeting minimum data completeness criteria as per national ambient air quality standards are included. The
annual average concentrations are computed based on valid daily observations, with only the maximum daily
concentration retained at each monitoring site to avoid duplicate reporting.