Chlorine and Occupational Health Issues (2025)

Description

This paper was compiled to give guidance on the assessment, evaluation, and control of occupational exposure to chlorine, with an emphasis on recommending a measurable health-based occupational exposure guidance value. The current Safe Work Australia (SWA) workplace exposure standards (WES) and proposed workplace exposure limits (WEL), as well as current international occupational exposure limits (OELs) for chlorine are discussed, and the possible health effects examined.

The AIOH acknowledges the importance of adhering to good control strategies to reduce exposures to as low as reasonably practicable (ALARP). SWA recommend a TWA of 0.1 ppm and 0.4 ppm peak which must not be exceeded. The AIOH suggests that a TWA value of 0.1 ppm (proposed by SWA), is not accurately measurable (based on currently available technology). The AIOH recommends a STEL of 1 ppm and a TWA of 0.5 ppm as guidance exposure values.

Any exceedances of these guidance exposure values should trigger investigation of the sources of exposure and implementation of suitable control strategies. Health risk relative to the recommended guidance exposure value level relating to the need for controls and health monitoring should be determined by a Certified Occupational Hygienist (COH)® applying the approaches and compliance decision making process detailed in ‘Occupational Hygiene Monitoring and Compliance Strategies’ published by the AIOH.

Control technologies have been developed and are available for successful implementation. The hierarchy of risk controls must be applied when determining the appropriate controls to be utilised. Most chlorine exposures may be adequately controlled by conventional means such as use of process safety controls and segregation of workers from areas of potential high concentration. Given the density of chlorine gas is 2.47 times greater than air, monitoring and controls should focus on low lying areas when there is little air movement. Whatever strategy is adopted it should be under-pinned by an effective maintenance program so that chlorine gas control effectiveness is sustained.