AQI catagory

Index values

PM_2.5 breakpoints (μg∙m⁻³)

Green good

0 - 50

0.0 - 12.0

Yellow moderate

51 - 100

12.1 - 35.4

Orange unhealthy for sensitive groups

101 - 150

35.5 - 55.4

Red unhealthy

151 - 200

55.5 - 150.4

Violet very unhealthy

201 - 300

250.5 - 350.4

Purple hazardous

301+

350.5+