The incoming comparator for dichloroacetic acid is an 8-hour time-weighted average of 2.5 mg/m³ (0.5 ppm). There was no previous exposure standard on this listing. Exposure standards remain the compliance reference until 30 November 2026. From 1 December 2026 the new limit applies once your WHS regulator gives it effect.
The published change does not include a short-term exposure limit. Do not write one into the report. Irritation and open-handling peaks still need a task description and an engineering note. They do not need a fabricated number.
Name the analyte before you pick media
Agree with the laboratory that the target is dichloroacetic acid. A “haloacetic acids” proxy is only defensible if the lab and the client have written why. Report milligrams per cubic metre and parts per million together when the method supports both, and say whether a ppm figure was measured or converted.
No historical standard does not mean there was no exposure. Say that in the background if the client treats a blank history as a blank risk.
Three clocks on one campaign
Drum or IBC charge, reactor sampling, and drumming are different durations on the same batch. Charge may be a few minutes at the bung. Sampling is short and close to the source, and it is easy to miss if you only attend on a day the plant calls “closed.” Drumming adds fill splash, bung vapour and a wipe. Filter, pump and valve breaks are infrequent and still define a group. Kilo-lab work is small volume in poor ventilation. Maintenance and contractors after hours never appear in a day-shift production set.
Plan the survey around a day that includes charge, sample or drum work. A day with none of those tasks cannot describe the campaign.
A three-minute charge and the eight-hour average
People ask whether a three-minute open charge “failed the limit.” Answer in two layers, and keep them apart in the table.
The limit you compare to is the 8-hour average of 2.5 mg/m³ (0.5 ppm). Collect a task sample on the charge (and on sampling and drumming if those are separate), then time-weight it into the shift. State what you assumed for the unsampled hours. If you assumed zero, say zero.
Report the task concentration as well. It is how you judge capture and irritation. It is not a short-term exposure limit, because none is published for this row.
Skin and eyes when the air looks fine
Dichloroacetic acid is an acid. Contact with skin and eyes can be the larger harm on an open charge even when the shift average sits well under 0.5 ppm. Say that in the interpretation. An air result does not close the risk assessment, and a recommendation that only escalates respiratory protection has missed the task.
How to sample it
Define groups from the task, not the roster title. Charge operators, sampling technicians, drumming, and maintenance may be one group or four; split them when the people and the open time differ.
Agree method and media that can resolve a meaningful fraction of 2.5 mg/m³ (0.5 ppm) before you mobilise. Run full-shift samples on representative campaign days and task samples on the first charge and on vacuum breaks, which is often when emission is highest. Record flow, blanks, breakthrough checks, humidity and co-contaminants. On the same sheet record charge count, whether local exhaust was on, and open minutes.
Note what respiratory protection was actually worn, so the reader can tell an unprotected reading from an as-worked one. Static samples at the bung are for capture. Label them as diagnostics, not as a personal average.
A non-detect only helps if the limit of detection sits at a meaningful fraction of 2.5 mg/m³. A high detection limit is not a comfortable result.
What the report should say
While you are still in the planning window, compare averages to 2.5 mg/m³ (0.5 ppm) so the client sees margin or deficit before December. From 1 December 2026, once the limit is in force, that figure is a limit not to be exceeded for people at the workplace.
Cite the laboratory method and the accreditation scope. Do not write “the Australian Standard requires…” unless you have checked that the current standard applies. Keep field notes good enough to rebuild why you split the groups. Do not file a sister-acid result as dichloroacetic acid without an agreed proxy statement.
If results sit near the limit, put closed transfer and fewer open samples first, then extraction at the bung, then written limits on who stands nearby. Fitted respiratory protection with a change schedule comes after those.
FAQ
Should every report quote both 2.5 mg/m³ and 0.5 ppm? Yes when the method supports both. Keep them as the published pair.
How many days are enough? Enough to see how open handling varies for the decision in front of you. One sealed day with no charge rarely settles an argument near 0.5 ppm.
Is there a published short-term limit on this row? No.
Sources
- Safe Work Australia, *Changes to Workplace Exposure Limits – May 2025*: https://www.safeworkaustralia.gov.au/sites/default/files/2025-05/changes_to_workplace_exposure_limits_-_may_2025.pdf
- Safe Work Australia, changes between exposure standards and exposure limits: https://www.safeworkaustralia.gov.au/safety-topic/managing-health-and-safety/workplace-exposure-limits-airborne-contaminants/changes-between-wes-and-wel
Technical support
Need a monitoring plan or a report review against the incoming limit? Start at occhygiene.com.au.
