Air pollutants National ambient air quality standard
SO2 Yearly 0.02ppm or less
24-hour 0.05ppm or less
1-hour 0.15ppm or less
CO 8-hour 9ppm or less
1-hour 25ppm or less
NO2 Yearly 0.03ppm or less
24-hour 0.06ppm or less
1-hour 0.10ppm or less
PM-10 Yearly 50㎍/㎥ or less
24-hour 100㎍/㎥ or less
O3 8-hour 0.06ppm or less
1-hour 0.1ppm or less
Pb Yearly 0.5㎍/㎥ or less
Benzene Yearly 5㎍/㎥ or less

PM-10 stands for particulate matter up to 10 micrometers in size.