Significance and Use
Most oxides of nitrogen are formed during high-temperature combustion. The Environmental Protection Agency (EPA) has set primary and secondary air quality standards for NO2 that are designed to protect the public health and the public welfare (40 CFR, Part 50).
Oxides of nitrogen are generated by many industrial processes that can result in employee exposures. These are regulated by the Occupational Safety and Health Administration (OSHA) which has promulgated exposure limits for the industrial working environment (29 CFR, Part 1910).
These methods have been found satisfactory for measuring oxides of nitrogen in the ambient and workplace atmosphere over the ranges shown in 1.1.
Scope
1.1 These test methods cover procedures for the continuous determination of total nitrogen dioxide (NO2) and nitric oxide (NO) as NOx, or nitric oxide (NO) alone or nitrogen dioxide (NO2) alone, in the ranges shown in the following table:
| Range of Concentration | ||
| Gas | Ambient Atmosphere | Workplace Atmosphere |
| μg/m3 (ppm) (Note 1) | mg/m3 (ppm) (Note 1) | |
| NO | 10 to 600 (0.01 to 0.5) | 0.6 to 30 (0.5 to 25) |
| (NO + NO2) = NOx | 20 to 1000 (0.01 to 0.05) | 1 to 50 (0.5 to 25) |
| NO2 | 20 to 1000 (0.01 to 0.5) | 1 to 50 (0.5 to 25) |
Note 1—Approximate range: 25°C and 101.3 kPa (1 atm).
1.2 The test methods are based on the chemiluminescent reaction between nitric oxide and ozone.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 9.
