Summary: Using real EPA Air Quality System data, this project maps who breathes dirty air in America. Air quality has dramatically improved since 2000 — PM2.5 down -42%, NO2 down -49%. But 2023 brought a shocking reversal: Canadian wildfire smoke pushed NYC's AQI to 218 — the worst air quality in modern history for the northeastern US. Los Angeles remains the most polluted major city. Chicago had 14 unhealthy days in 2023, the most of any tracked city.
Key Findings
Cleanest city 2023
Seattle
Most polluted 2023
Los Angeles
PM2.5 down since 2000
-42%
NO2 down since 2000
-49%
States above PM2.5 std
0
2023 NYC wildfire AQI
AQI 218
Charts & Analysis
City AQI Comparison
2019–2023
AQI Days by Category
2023 breakdown per city
National Air Quality Improvement
2000–2023 all pollutants
PM2.5 by State Heatmap
vs 12 μg/m³ NAAQS standard
Unhealthy Days Trend
2023 wildfire smoke spike
COVID & Air Quality
Did lockdowns clean the air?
Data Source
US EPA Air Quality System (AQS) — https://www.epa.gov/outdoor-air-quality-data
All data is real, publicly available government data. Free to download and verify independently.