1. Scope

1.1

This Standard applies to the continuous measurement of ozone in air.

1.2

This Standard sets forth the chemiluminescence method for the measurement of concentrations of ozone between 2 ?g?m-3 and 10 mg?m-3 at 25?C and 101.3 kPa (approximately 0.001 ppm v/v and 5 ppm v/v).

Notes: (1) All concentrations referred to throughout this Standard are based on a temperature of 25?C and an atmospheric pressure of 101.3 kPa unless otherwise stated.

(2) Two calibration procedures are described: the ultraviolet photometric method and the use of transfer standards.

1.3

Ultraviolet photometry is used in this Standard only for the primary calibration of ozone atmospheres. However, this Standard recognizes that, under many circumstances, ultraviolet photom etry can be used as an alternative ozone-monitoring method. A brief outline of this instrumental method and its limitations are given in Appendix A. However, this method shall first be shown to be equivalent to the chemiluminescence method in the area where it is intended to be used.

Notes: (1) For additional information on equivalence testing, see Bibliography, Item 1.

(2) It is essential to differentiate between the use of an ultraviolet photometer as an ambient analyser and its use as a calibration photometer. An ultraviolet analyser cannot be considered to be ""self-calibrated"" and must always be calibrated with an independent calibration photometer or an acceptable transfer standard. An ultraviolet photometer used for calibration must be dedicated to such use and must be meticulously maintained.