On 1 December 2026, the list of airborne contaminant limits that applies on every Australian building site is replaced. Most of the coverage so far has treated this as a change of name. It is more than that. Sitting in the comparison table are reductions that land directly on residential work, including a tenfold cut to the limit for Portland cement dust and the first national limit Australia has ever set for diesel exhaust.
Safe Work Australia published three new guides on 30 July aimed at helping workplaces prepare. Two deal with air monitoring, one for employers and one written for occupational hygienists. The third covers diesel engine emissions and names construction among the sectors it is written for. None of them lead with the numbers, which is where the change actually bites.
What Actually Changes on 1 December
The Workplace Exposure Standards list, adopted in 1995 and last comprehensively reviewed in 2003, becomes the Workplace Exposure Limits list. The renaming was deliberate. Work health and safety ministers agreed to the word limit to make clear these are ceilings that must not be exceeded, and to bring Australian terminology into line with the language used internationally.
Until 30 November the existing exposure standards continue to apply. From 1 December the new limits apply, subject to each jurisdiction implementing them into its own laws.
The review did three things. It added 31 airborne contaminants to the list. It changed the limits for a long list of existing substances, most of them downwards. And it removed limits entirely for 33 chemicals identified as non threshold genotoxic carcinogens. For anyone who deals with the compliance side of running a site, the practical significance is that a figure a builder has worked to for two decades may no longer be the figure that applies.
The Numbers That Land on a Residential Site
These figures come from Safe Work Australia’s own comparison document, last updated 29 May 2025. Limits are expressed as milligrams of substance per cubic metre of air, written as mg/m3, measured as an average across an eight hour working day unless noted otherwise.
Portland cement
Currently 10 mg/m3, measured as inhalable dust. From 1 December the entry becomes Portland cement measured as respirable dust, at 1 mg/m3. That is two changes in one, and the second matters more than the first. The number drops by a factor of ten. The fraction being measured also shifts from inhalable dust, meaning everything drawn in through the nose and mouth, to respirable dust, the much finer portion that travels deep into the lung. Because respirable dust is a subset of inhalable dust, the practical tightening is greater than the tenfold cut in the number suggests. Cement dust is generated by mixing, dry cutting, grinding, chasing, handling bagged product and sweeping up. It is the single most widely relevant change on the list for residential builders, and it is the one attracting the least attention.
Diesel particulate matter
A new entry at 0.01 mg/m3, measured as respirable elemental carbon. There has been no national exposure limit for diesel exhaust in general industry before now. Open air detached housing sites will rarely approach that figure. Basement excavations, undercroft and garage slabs, plant rooms and any partly enclosed area with an excavator, generator or compactor running are a different proposition.
Softwood dust
Falls from 5 mg/m3 to 2 mg/m3, and the short term limit of 10 mg/m3 is removed. Pine framing, sawing, sanding and routing all generate it. Hardwood dust does not appear among the substances changing and carries across unchanged.
Bitumen fumes
Fall from 5 mg/m3 to 0.5 mg/m3. Relevant to driveways, torch on membranes and hot applied waterproofing.
Lime products
Calcium hydroxide, better known as hydrated lime, falls from 5 mg/m3 to 1 mg/m3 with a new short term limit of 4 mg/m3. Calcium oxide, or quicklime, drops from 2 mg/m3 to 1 mg/m3. Both turn up in mortar, render and soil stabilisation.
Isocyanates
The direction of travel here is the opposite of what it looks like at first glance. At present a single grouped entry covers all isocyanates at 0.02 mg/m3 with a short term limit of 0.07 mg/m3. From 1 December that group is broken apart into individual listings, with the two used most widely in spray foam insulation, two pack paints and adhesives moving under a polyisocyanate entry expressed as NCO. For those products the numbers do not move. The restructure still matters for anyone whose safety data sheets reference the old grouped listing, because the entry being pointed at will no longer exist.
Welding and hot work
Manganese moves from a single limit of 1 mg/m3 to two entries: 0.1 mg/m3 for the inhalable fraction and 0.02 mg/m3 for the respirable fraction. That is a reduction by a factor of ten and fifty respectively. Zinc oxide, the substance behind metal fume fever when cutting or welding galvanised steel, drops from 10 mg/m3 as dust and 5 mg/m3 as fume to a single combined limit of 2 mg/m3 with a short term limit of 10 mg/m3.
Two separate welding fume reductions have already happened and are not part of the December change. The limit for welding fumes not otherwise classified fell from 5 mg/m3 to 1 mg/m3 in January 2024. The limit for aluminium welding fumes fell from 5 mg/m3 to 1 mg/m3 from 17 November 2025, bringing it into line with the first. Air monitoring data collected before those dates was measured against numbers that no longer apply.
Solvents
Toluene falls from 50 parts per million to 20. Mineral turpentine drops from 480 mg/m3 to 296 mg/m3, and white spirits from 790 mg/m3 to the same figure, both with new short term limits. Acetone halves from 500 parts per million to 250.
The Limits That Disappear Entirely
Thirty three chemicals classified as non threshold genotoxic carcinogens lose their exposure limits from 1 December. That sounds permissive and is the opposite. These are substances for which no safe level of exposure can be identified from the available evidence, so publishing a number would imply a safety margin that does not exist. Where they are present, the obligation is to eliminate them, substitute something safer, or reduce the risk so far as is reasonably practicable.
The list includes chromium six compounds, which occur in fume from welding stainless steel and in some primers, and coal tar pitch volatiles. A further six chemicals come off the list simply because they are already prohibited from import, manufacture and use in Australia.
Silica Is the Substance Not Changing, Yet
Respirable crystalline silica does not appear in the December change table. Its limit of 0.05 mg/m3 carries across unchanged.
That is not because the review found nothing. Silica is one of nine substances where ministers requested further impact analysis before a final value is set, alongside benzene, formaldehyde, chlorine, copper, hydrogen cyanide, hydrogen sulphide, nitrogen dioxide and titanium dioxide. Until that work concludes, the existing number holds.
The framework around silica keeps tightening regardless of where the number lands. Separate silica specific obligations already apply in most jurisdictions, and enforcement posture has already shifted in the states that have made dust a campaign priority.
When Air Monitoring Is Actually Required
Air monitoring is the part of this that most residential builders have never had cause to think about, and it is what two of the three new guides are about.
Under the model work health and safety regulations, monitoring is required in two situations. The first is where the person conducting the business is not certain, on reasonable grounds, whether the airborne concentration exceeds the relevant exposure standard. The second is where monitoring is necessary to determine whether there is a risk to health at all.
Uncertainty is the operative word. A builder with no measurements and no data from comparable work meets that description by definition.
Monitoring has to be carried out by a competent person, which in practice means an occupational hygienist. Under the model regulations the results must be recorded, kept for 30 years from the date the record is made, and made readily accessible to anyone at the workplace who may be exposed. Victoria goes a step further and requires that results be given to affected employees as soon as possible, whatever those results show.
The retention period is the part small businesses most often miss. Occupational lung disease presents decades after the exposure that caused it. The monitoring record is what establishes when a worker was exposed, to what, and at what concentration. Thirty years is not administrative caution. It is the latency period of the diseases these limits exist to prevent.
Whether 1 December Applies Everywhere
The date is a harmonised target rather than an automatic national switch. The limits take effect in each jurisdiction once that jurisdiction has implemented them into its own laws. This is not a technicality invented for the transition. Safe Work Australia has long carried a note on the exposure standards list itself stating that changes to the list do not automatically take effect in all jurisdictions, and that when they do depends on how the standards are referenced in that jurisdiction’s laws.
Most states and territories, along with the Commonwealth, operate versions of the model work health and safety laws and will pick the list up through amendments to their own regulations. Western Australia runs its own Work Health and Safety Act 2020 and its own regulatory process.
Victoria never adopted the model laws at all. It operates under the Occupational Health and Safety Act 2004 and the Occupational Health and Safety Regulations 2017. WorkSafe Victoria’s stated position is that the Safe Work Australia exposure standards list applies in Victoria while other work health and safety provisions referenced alongside it do not. As of its most recent review of that guidance, WorkSafe Victoria described the December changes as proposed and runs a separate subscription for Victorian updates.
For a builder working across a border, that raises a practical possibility worth watching: the same task, generating the same dust, sitting under two different numbers for a period.
The Good Builder Take
The change most likely to catch residential builders is not the one getting the coverage. Diesel exhaust has the new limit, the new guidance and the headlines. Portland cement has a tenfold reduction, a shift in the fraction being measured, and no dedicated guidance at all. It applies to mixing, cutting, grinding and sweeping, which is to say work that happens on almost every site, almost every week.
What Sits Between Now and December
Nothing in the transition requires anyone to have measured anything by 1 December. The obligation on the day is the same obligation that exists now: no worker exposed above the limit. What changes is the limit, and in the case of cement dust, the fraction being measured.
Where air monitoring data already exists, it was measured against the old figures and in some cases the old fraction. A result that demonstrated compliance at 10 mg/m3 of total cement dust says nothing about compliance at 1 mg/m3 of respirable dust. They are not the same measurement.
Where no data exists at all, the controls themselves carry the weight. On tool extraction, wet cutting, ventilation in enclosed areas and keeping diesel plant out of confined spaces where it can sit and idle are the measures that determine whether a number is ever approached in the first place.
The Point
The list being replaced in December was adopted in 1995 and last reviewed properly in 2003. That gap is why some of the reductions look severe. They are not sudden. They are twenty years of accumulated health evidence arriving at once, because the evidence moved faster than the list did. What lands on 1 December is not new science. It is the paperwork catching up, in the same way other compliance dates arriving on the calendar have caught up over the past two years.
The builders who find this uncomfortable in December will be the ones who assumed the old numbers were a safety margin rather than a ceiling. The ones who treated dust as something to control rather than something to measure against will find very little has changed.
Frequently asked questions
Functionally they do the same job, and the change of wording was deliberate. Ministers agreed to replace the word standard with limit to make clear that these figures are ceilings that must not be exceeded rather than targets, and to align Australian terminology with the language used internationally. The substantive difference is in the numbers themselves, which were revised as part of the same review.
The limit for Portland cement drops from 10 mg/m3 to 1 mg/m3, and the measurement changes from inhalable dust to respirable dust. Inhalable dust is everything drawn in through the nose and mouth. Respirable dust is the finer fraction that reaches deep into the lung and is a subset of it. So the new limit is both a lower number and a measurement of a smaller particle size, which makes the real tightening greater than ten times.
From 1 December 2026, yes. Diesel particulate matter is added to the list at 0.01 mg/m3, measured as respirable elemental carbon. There was no national limit for it in general industry before this. Safe Work Australia’s guidance on diesel engine emissions names construction among the sectors it applies to, alongside mining, quarrying, tunnelling, transport and vehicle maintenance.
No. Respirable crystalline silica is one of nine substances where ministers requested further impact analysis before a final figure is set. Its limit of 0.05 mg/m3 carries across unchanged when the new list takes effect, and any future change would come out of that separate process.
Under the model work health and safety regulations, monitoring is required where the person conducting the business is not certain on reasonable grounds whether the airborne concentration exceeds the relevant exposure standard, or where monitoring is needed to determine whether there is a risk to health. It has to be done by a competent person, and the results must be recorded, kept for 30 years, and made readily accessible to anyone at the workplace who may be exposed.
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General information only. This article does not constitute legal, financial, or professional advice. Figures are drawn from Safe Work Australia’s published comparison of changes to workplace exposure limits, last updated 29 May 2025, and were current at time of publication. Exposure limits take effect in each state and territory only once implemented into that jurisdiction’s own laws. Verify current obligations with your state or territory work health and safety regulator before acting.
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