| Abstract: | The sodium arsenite method for measurement of nitrogen dioxide in ambient air was evaluated. The method has a constant-high collection efficiency (82%) for nitrogen dioxide, and is insensitive to normal variations in operating parameters. Nitric oxide and carbon dioxide are positive and negative interferents, respectively. The combined average effect of these interferents, over ambient levels, is a positive bias of 9.9 µg/m3. This bias, although statistically significant, is minor ( 10 % ) in relation to the ambient air standard of 100 µg NO2/m3 and does not warrant modification of the method to remove the interference. |
