Nitrogen dioxide is the chemical compound with the formula NO2. It is one of several nitrogen oxides. NO2 is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year. At higher temperatures it is a reddish-brown gas that has a characteristic sharp.


Nitrogen Dioxide

Time-weighted average

660 (0.35) -100 (0.05) µg/Nm3 (ppm)

Averaging time

1 hour-Annual

Time –weighted average Averaging Time Number of allowable exceedances
350 ppb 1-hour 2 times within 30 days
50 ppb annually None
Number of allowable exceedances

2 times per 30 days N/A