What Level Of PM2 5 Is Unhealthy?
What Level Of PM2 5 Is Unhealthy? AQI Category Index Values Revised Breakpoints (μg/m3, 24-hour average) Unhealthy for Sensitive Groups 101 – 150 35.5 – 55.4 Unhealthy151 – 200 55.5 – 150.4 Very Unhealthy 201 – 300 150.5 – 250.4 Hazardous 301 – 400 250.5 – 350.4 Is PM 2.5 really dangerous? Fine particles (PM2.5)