scope:

This document specifies a method for the sampling of NO₂ in ambient air using diffusive sampling followed by extraction and analysis by colorimetry or ion chromatography (IC). It can be used for the NO₂ measurement in a concentration range of approximately 3 μg/m3 to 130 μg/m³ [12]. A sample is typically collected for a period of 1 to 4 weeks [14], with exposure periods depending on the design of the samplers and the concentration levels of NO₂.

Several sorbents can be used for trapping NO₂ in ambient air using a diffusive sampler [15]. This document specifies the application of triethanolamine as the reagent.

This document describes the application of a tube-type sampler (with either a cylindrical or a slightly conical tube), a badge-type sampler and a radial-type sampler.

The relative expanded uncertainty of NO₂ measurements performed using these tube-type diffusive samplers can potentially be lower than 25 % for individual measurements. When aggregating results to form annual average values, the relative expanded uncertainty can be further reduced to levels below 15 % due to the reduction of random effects on uncertainty [9].

NOTE NO₂ passive samplers are also employed to measure NO_x with the addition of an oxidant to convert ambient NO into NO₂. A second NO₂ sampler is also deployed without the oxidant and the concentration of NO is determined from the difference of the two samplers [16].