5.1 Hexavalent chromium has been shown to be a human respiratory carcinogen in epidemiological studies when humans are exposed to relatively high airborne concentrations. Such high exposures may also induce dermal sensitization to hexavalent chromium in humans (5).

5.2 Ambient atmospheric concentrations of hexavalent chromium are well below detection limits of sampling methods including Test Method D3586 and NIOSH-7600 (2).

5.3 Objective assessment of ambient atmospheric concentrations of hexavalent chromium provides a means of evaluating exposures to atmospheric hexavalent chromium in a manner that can be related to health-based risk levels. Collecting such actual monitoring data reduces or eliminates the need for theoretical resuspension modeling and provides improved basis for health assessments of potential exposures (5).

5.4 The buffered impinger sampling technique provides pH control of the sampling medium, which stabilizes the oxidation state of hexavalent chromium during sampling (6) .

5.5 Ion chromatography provides a means of separating the hexavalent chromium from other species present in the sample, many of which interfere with other detection methods. The combination of this separation with a sensitive colorimetric detection method provides a selective and sensitive analytical method for hexavalent chromium with minimal sample preparation (1).

1.1 This test method covers the collection and measurement of hexavalent chromium [Cr(VI)] in the ambient atmosphere.

1.2 This test method collects and stabilizes atmospheric hexavalent chromium using an alkaline impinger buffer solution in a wet impingement sampling technique. Lead chromate [PbCrO₄], generally considered poorly soluble in water, is soluble in the impinger solution up to 940 μg/L as hexavalent chromium.

1.3 This test method measures hexavalent chromium using an ion chromatographic separation combined with a post separation reaction with a colorimetric reagent and photometric detection.

1.4 This test method is applicable in the range from 0.2 to 100 ng/m³ of hexavalent chromium in the atmosphere assuming 20 m³ of air sample. The range can be extended upwards by appropriate dilution.

1.5 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.

1.6 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.