Insights: Lafayette-West Lafayette, IN metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 43 over 270 measured days in 2025, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 184 Good days (68%), 85 Moderate (31%), and 1 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 64 while the highest single-day reading hit 105 (USG). Metro residents averaged roughly 20.4 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by +5 and the median AQI moved -8 points, which classifies the multi-year trajectory as improving. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Allentown-Bethlehem-Easton, PA-NJ (65.6% good, AQI 43); Amarillo, TX (75.7% good, AQI 43); Ashtabula, OH (81.2% good, AQI 43).