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. 2022 Apr 6;12:5753. doi: 10.1038/s41598-022-09344-0

Table 2.

Air quality standards.

Pollutant Level I Level II Level III Level IV Level V
SO2 50 125 250 350 450
NO2 40 80 120 160 200
CO 2 4 6 8 10
O3 100 160 200 265 320
PM10 50 150 250 350 420
PM2.5 25 75 115 150 250