Peracetic acid WEL: a 0.4 ppm peak limitation for sanitation SEGs

From 1 December 2026, peracetic acid has a Workplace Exposure Limit (WEL) for the first time. Safe Work Australia lists it as a peak limitation of 0.4 ppm (1.24 mg/m³). The listing has no 8-hour TWA and no STEL.

A peak limitation is the maximum concentration measured over the shortest time possible, not exceeding 15 minutes. In Safe Work Australia’s words, “Exposure above the peak limitation is not allowed at any time.” So the short, open-handling jobs on sanitation shifts are the ones to plan around. A full-shift average can look comfortable while a quick make-up at the day tank goes over the limit.

When the peak limitation applies

Until 30 November 2026, the current Workplace Exposure Standards (WES) list remains the compliance reference, and peracetic acid has no entry on it. The WEL list takes over from 1 December 2026, once your jurisdiction’s WHS regulator gives it effect. Victoria sits outside the model WHS laws, so Victorian sites should check with WorkSafe Victoria on how and when the new list will apply there.

Use the months before December to find out where your peaks are. Nothing about peracetic acid is limited by the WEL list before 1 December.

Why sanitation SEGs carry this one

Peracetic acid (PAA) turns up wherever sites sanitise CIP circuits, fillers, aseptic lines and hard surfaces. Risk assessments often describe it as production chemistry on a closed circuit. Meanwhile the people who pour, fog, spray and break containment on sanitation shifts can sit outside the SEG map altogether.

With a peak limitation, those brief moments of open handling are the compliance question. They mostly happen during sanitation and maintenance work, often at night and often done by contractors.

If your register lists hydrogen peroxide or acetic acid but never names peracetic acid in blends, you may already have a naming gap.

Where peracetic acid shows up

Typical Australian settings:

• Food and beverage CIP: circuit make-up, dosing skids, open sampling of sanitiser tanks
• Dairy, brewery, juice and soft-drink filler sanitation between SKUs
• Pharma and biotech surface sanitisation by spray or fog
• Aseptic packing and clean-room turnaround
• Meat and poultry sanitation bays
• Contract cleaning crews who apply PAA blends after hours
• Drum and IBC decanting into day tanks; filter and pump maintenance on sanitiser lines
• Spill response where concentrated stock is handled

Vapour and mist matter as much as liquid splash. Open pour, fogging, spray wands and warm CIP return lines are where the highest short-term concentrations tend to occur, even when the production SEG looks tidy.

SEG walkthrough (beverage CIP example)

Take a beverage site that makes up PAA sanitiser in a day tank and runs automated CIP on its fillers. Night cleaners then fog floors and walls with a dilute spray.

SEG candidates

1. CIP and dosing operators: make-up, titration sampling, IBC connection
2. Filler sanitation crew: open spray and wand work at the filler carousel
3. Night fog and clean team: often contractors, with a different profile from day CIP
4. Maintenance: pump, filter, valve and gasket work on sanitiser lines
5. Lab and micro: small-volume handling that still gives off vapour in poorly ventilated rooms

For each SEG, write down the moment most likely to give the highest reading. Examples are the IBC coupling, the open sample at the day tank, the start of a fog run and the first valve break after a flush.

Walkthrough questions with ops

• When in each CIP cycle is the system open, and for how long?
• Is make-up done under LEV, outdoors, or in a closed corridor with no capture?
• Who fogs after hours, and were they inducted on peracetic acid by name or on “sanitiser” in general?
• Are stock concentrations and use-dilutions both on the register?
• Does anyone treat “no smell” as the exposure measure?

Build SEGs from those answers. Job titles on the roster won’t get you there.

Register and SEG questions for HSE and ops

1. Is peracetic acid named on the hazardous chemical register, including in proprietary sanitiser blends?
2. Which SEGs could inhale vapour or aerosol during make-up, filler spray, fogging, maintenance or lab work?
3. Are the SDS and emergency procedures current for PAA, including its oxidiser and incompatibility hazards?
4. Do permits for line-breaking treat vapour release during sanitiser circuit work as foreseeable?
5. Was any past monitoring full-shift only? If so, it says little about peaks and needs task-level follow-up.
6. Who owns elimination and substitution before RPE becomes the default for fogging?
7. Are spill kits and dilution practices compatible with the SDS, and have people practised indoor vapour scenarios?
8. Do contractors appear in the SEG map with PAA named, rather than buried under “hygiene chemicals”?

If sanitation is outsourced, the PCBU still needs the substance named and the SEG logic written down.

Controls for the peak moments

Eliminate or substitute

• Can fogging be replaced with closed CIP or wipe systems where efficacy allows?
• Can stock strength drop, or make-up move to closed dosing skids?
• Can open spray campaigns run less often without losing hygiene outcomes?

Write down the residual risk of each alternative so the substitution decision is on record.

Engineering

• Closed dosing and sealed sampling points
• Vapour return where practicable
• Local exhaust at make-up points and open spray booths, with capture checked at real spray rates
• Gaskets, seals and pump packing on sanitiser circuits maintained as engineering controls
• Filter and strainer changes planned so lines are drained and flushed before the break, cutting open volume

Administrative

• Keep open pour and fog dwell time short, with written methods and non-essential people kept clear
• Separate sanitation SEGs from production SEGs in training and monitoring plans
• Set stop-work triggers for eye or throat irritation, visible mist escape, LEV failure or a direct-reading alarm, without treating odour as a calibrated instrument
• Make sure contractor inductions name peracetic acid and the 0.4 ppm (1.24 mg/m³) peak limitation

PPE

• Chemical-protective gloves and clothing compatible with PAA (check permeation data)
• RPE selected for the vapour and mist hazard at peak concentrations, with fit testing and cartridge or filter change rules
• Eye and face protection suited to splash and mist during open spray

Storage and segregation matter too. Keep PAA away from incompatibles as the SDS directs, because a tidy chemical store helps prevent unplanned airborne release.

Monitoring for a peak limitation

An 8-hour TWA result can’t show compliance with a peak limitation. A shift average smooths out the very moments the limit is written for. Monitoring should target those moments directly:

• Sample the highest-concentration tasks: dosing, CIP make-up, decanting, opening tanks or lines, and fog start-up.
• Use short-duration samples and, where a suitable instrument exists, real-time direct-reading monitoring that logs the task as it happens.
• Keep sample periods as short as the method allows and never longer than 15 minutes. Ask your occupational hygienist what the shortest practicable period is for the method they propose.
• Compare the highest result with 0.4 ppm. An average across samples is the wrong comparison.
• Report in ppm, with mg/m³ alongside. SWA says the ppm figure is exact and the mg/m³ figure is a guide.
• Repeat across sanitation cycles and contractor shifts, since one clean make-up may have been luck.

Results collected before December give you a baseline for the 1 December limit. They aren’t compliance results against a current standard, because the WES has no entry for peracetic acid.

Common mistakes

• Register lists “peroxide sanitiser” but never names peracetic acid
• Monitoring production only and skipping night fog and CIP make-up
• Running full-shift samples and reading them against 0.4 ppm
• Recording 0.4 ppm as a TWA or a STEL on the register or in toolbox talks
• Treating odour as either proof of exceedance or proof of safety
• Emergency plans that cover skin splash but ignore inhalation during indoor fogging

FAQ for HSE and operations

We only fog once a week. Do we still need a SEG?

Yes, if people can inhale vapour or mist during that programme. A peak limitation applies to every exposure, so a weekly task counts as much as a daily one.

Is 0.4 ppm the same as 1.24 mg/m³?

They are the same limit in two units. Where a WEL is given in both, SWA treats the ppm figure as exact and the mg/m³ figure as a guide.

Does peracetic acid have a TWA or STEL?

No. The WEL listing gives a peak limitation only. SWA also notes that a peak limitation can’t be adjusted for longer or shorter working days, so long sanitation shifts don’t change it.

When does the WEL count?

The WES stays the reference until 30 November 2026. The WEL applies from 1 December 2026 once your jurisdiction’s WHS regulator gives it effect. Check with your regulator, and in Victoria with WorkSafe Victoria.

Sources

• Safe Work Australia, Workplace exposure limits for airborne contaminants (amended November 2025), PDF: https://www.safeworkaustralia.gov.au/sites/default/files/2025-11/workplace-exposure-limits-amended-november_2025.pdf
• Safe Work Australia, Changes to Workplace Exposure Limits (May 2025), PDF: https://www.safeworkaustralia.gov.au/sites/default/files/2025-05/changes_to_workplace_exposure_limits_-_may_2025.pdf
• Safe Work Australia, Workplace exposure standards for airborne contaminants (amended November 2025), PDF: https://www.safeworkaustralia.gov.au/sites/default/files/2025-11/workplace-exposure-standards-amended-november2025.pdf

Next step

If peracetic acid is used for CIP, fogging, spray sanitisation or make-up on your site, book a consult to map your sanitation SEGs and plan peak monitoring before the WEL date.

Book a consult: anitechgroup.com · sales@anitechgroup.com