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weather condition

The Mutianyu Great Wall
China PM2.5 classification standard
Serial number PM2.5 Value μg/m³ Air quality class
1 0~35 excellent
2 35~75 good
3 75~115 Mild pollution
4 115~150 Moderate pollution
5 150~250 Heavy pollution
6 250 above Serious pollution
Classification standard of negative oxygen ion in China
Air quality class Negative oxygen ion content Unit/cm³ Air freshness
1 More than 2000 Very fresh
2 1500 - 2000 fresh
3 1000 ~ 1500 It is fresh
4 500 ~ 1000 General fresh
5 Less than500 Not fresh
China PM10 grading standard
Serial number PM10 Value μg/m³ Air quality class
1 0~50 excellent
2 50~150 good
3 150~250 Mild pollution
4 250~350 Moderate pollution
5 350~420 Heavy pollution
6 600 above Serious pollution