Advisory, Alert and Emergency Levels:

Section 244 Section 244.161   Advisory, Alert and Emergency Levels: Pollutant Averaging Time Advisory Yellow Alert Red Alert Emergency Sulfur dioxide (ppm) 2-hour 0.30 -- -- -- 4-hour -- 0.30 0.35 0.40 (PM 10 µg/m 3 2-hour 420 -- -- -- 24-hour -- 350 420 500 Carbon Monoxide (ppm) 2-hour 30 -- -- 8-hour -- 15. 30. 40. Ozone (ppm) 1-hour 0.12 0.20 0.30 0.50 Nitrogen dioxide (ppm) 2-hour 0.40 -- -- -- 1-hour -- 0.60 1.20 1.60 24-hour -- 0.15 0.30 0.40