Hexavalent chromium in air monitoring: Unique challenges in non-routine collection

Air monitoring and analysis is a well-established and commonplace practice in industry settings, which includes hexavalent chromium (CrVI). Being a particularly hazardous substance and a select carcinogen, CrVI is closely monitored, and has very strict limits on workplace exposure. CrVI is typically monitored for applications which include spray painting, welding, and electroplating, and while the concentration limit varies by governing body, the permissible limits are always extremely low. For routine analysis, the OSHA methodology requires long sampling times and large volumes to achieve these low limits of detection. The OSHA ID215 standard method utilizes post-column derivatization ion chromatography to accommodate these low limits. This method proves to be problematic, however, in
cases where lower limits, such as the 25-times-lower ACGIH limit are imposed, or where long sampling times are not reasonably achievable. This can be further complicated by differences between the OSHA and ACGIH sampling requirements (e.g., respirable fraction versus inhalable fraction collection). In these instances, the sampling and analysis method has proven to be unreliable. Applying the OSHA sampling and analysis methodologies to the analysis of CrVI yields highly inconsistent data, making it impossible within currently accepted techniques to measure against the ACGIH time weighted average threshold limit value. Here we detail the data collected—both in simulated low-level exposure near the ACGIH
limits and in real-world field collected samples where short sampling times must be imposed—and analyzed for CrVI using the standard OSHA methodology in order to demonstrate this shortcoming, and to reveal the need to develop new methods capable of addressing this need.