Ministers could not agree to tighter limits for silica, benzene and seven other chemicals. The old numbers carry over in December.

What was decided, and what was not

The nine chemicals are benzene, chlorine, copper, formaldehyde, hydrogen cyanide, hydrogen sulphide, nitrogen dioxide, respirable crystalline silica and titanium dioxide. When ministers agreed in 2024 to replace the workplace exposure standards (WES) list with new health-based workplace exposure limits, these nine were carved out for a further round of impact analysis, because they drew the strongest stakeholder objections on cost and measurability. That analysis, a 247-page Decision Regulation Impact Statement prepared at ministers' request and published on 24 June 2026, recommends implementing the tighter health-based limits for all nine. The ministers' answer, recorded in Safe Work Australia's publication notice: "A majority in support of new workplace exposure levels for the 9 chemicals has not been reached and a majority of ministers have requested further work. There will be no changes to the exposure limits for the 9 chemicals from 1 December 2026."

The numbers that will not change

Current standards (which carry over as the limit on 1 December 2026) against the health-based limits the Decision RIS recommended. TWA is the eight-hour time-weighted average; STEL the 15-minute short-term limit; peak the maximum at any time. Transcribed from Table 3 of the Decision RIS.

The scale of some of those declined reductions is worth reading twice. Nitrogen dioxide would have dropped fifteen-fold. Hydrogen sulphide, the gas that kills in confined spaces, would have dropped ten-fold. Benzene, a known carcinogen, five-fold. These were not incremental adjustments, which is exactly why they were expensive, and why they were fought.

1 December still happens. It just skips these nine.

None of this delays the transition itself. Ministers agreed in 2024 to a harmonised implementation date of 1 December 2026 for the workplace exposure limits for airborne contaminants, the list that replaces the WES list once each jurisdiction writes it into its WHS laws. From that date the vocabulary changes everywhere (the Decision RIS puts it in one line: the WES are "from 1 December 2026 to be known as the workplace exposure limits"), and hundreds of chemicals move to the new health-based numbers that ministers did agree, some of them substantially lower than today's. The nine carve-outs keep their old values inside the new list. A duty holder updating their chemical register for December should therefore run two checks, not one: which of your substances got a new number, and which of these nine kept an old one. The register, label and SDS obligations that hang off every workplace chemical are covered on the chemical storage page.

Silica: banned in benchtops, unchanged in the air

Respirable crystalline silica is the politically hardest entry on the list, and the one with the sharpest recent history. In December 2023 ministers agreed unanimously to ban engineered stone, and the prohibition took effect in July 2024, a world first, covered on the silica page. Eighteen months later, the same ministers' meeting could not assemble a majority to halve the airborne limit that applies to every silica-exposed workplace, from 0.05 to 0.025 mg/m³. The current 0.05 standard is itself the product of a previous halving, from 0.1 mg/m³, a reduction stakeholders cited in consultation as still bedding in alongside the 2024 crystalline silica substance regulations. The Decision RIS quantifies what made this one so hard: outside mining, it estimates the tighter silica limit would return about $10.1 billion in benefits against $3.4 billion in costs over ten years, the only clearly positive quantified case among the nine. Within mining, it estimates $2.5 billion in benefits against $18.5 billion in costs. One proposed number, two economies.

The standard that stays is a ceiling, not a safe level

The practical trap in this decision is reading "no change" as reassurance. The Decision RIS itself argues the opposite, in terms a court or regulator could one day quote back at a duty holder: evaluation of the current WES for each of the nine chemicals "has determined they are not health-based", and retaining them "is likely to imply to workers a false sense of safety", namely "that exposure at the level of the WES will not cause adverse health effects". An exposure standard has never been a target; the primary duty under section 19 of the model WHS Act still requires exposure to be minimised so far as is reasonably practicable, below the limit, not up to it. From December, a PCBU with airborne silica, benzene or formaldehyde exposure will hold a published national document stating that compliance with their unchanged limit does not, on current evidence, protect their workers. That document is now part of what is reasonably knowable, which is the currency the WHS duty trades in. The one exposure standard regime that did move years ago, noise, shows what a hard legal limit looks like in operation, on the noise page.