How did we get to ‘Workplace Exposure Limits’?Australia first adopted the workplace exposure standards for airborne contaminants (WES list) in 1995. Since the last comprehensive review in 2003, more evidence has emerged in relation to the harmful effects, and the thresholds below which no adverse effects are observed, for many chemicals.Following the WES review, work health and safety (WHS) ministers across the country agreed to the WES list becoming the workplace exposure limits for airborne contaminants (WEL list) and changes to the exposure limits of some chemicals. The WEL list was set to be adopted in Australia on 1 December 2026, following implementation into Commonwealth, state, and territory WHS laws.A process to review WESs was developed and agreed to by WHS Ministers before the WES review started to guide the review process, including:which scientific sources to usewhich chemicals should be added or removed from the WES list, andwhich notations (standards) should be considered.The review commenced in 2019 and concluded in 2024, leading to the adoption of the WEL list.In relation to these thresholds, the national regulator - Safe Work Australia (SWA) developed the national policy – the WEL list, while Commonwealth, states and territories have the responsibility of regulating and enforcing these WHS laws. What to know about the legislationThe federal Work Health and Safety Act 2011 establishes the national approach to workplace health and safety and defines key concepts such as worker, workplace, and person conducting a business or undertaking (PCBU), and outlines duties for employers, workers, and other parties.PCBUs (the primary duty holder responsible for ensuring worker health and safety) are required to eliminate risks to health and safety, so far as is ‘reasonably practicable’; and if this is not reasonably practicable, they are required to minimise those risks so far as is reasonably practicable.‘Reasonably practicable’ in Australian WHS law means taking all measures to ensure health and safety that are possible and reasonable in the circumstances, balancing risk against the effort, time, and cost required to control it.In discharging their primary duty, a PCBU is required to manage the risks to health and safety associated with the use, handling etc. of hazardous chemicals at the workplace in accordance with WHS Regulations (including WELs).The WHS Regulations also require a PCBU to ensure that no person at the workplace is exposed to a substance or mixture in an airborne concentration that exceeds the exposure level for the substance or mixture.PCBUs are also required to conduct air monitoring if they are not certain on reasonable grounds whether the airborne concentration of a substance at the workplace exceeds the exposure level or where the monitoring is needed to determine if there is a risk to health. WEL list and applicationThere are three different kinds of exposure limits, or thresholds, used in the 31-page long WEL list:8-hour time weighted average (TWA),short term exposure limit (STEL), andpeak limitation.Some airborne contaminants have more than one kind of exposure limit, e.g., a TWA and a peak limitation or a STEL.The list and guidance about what each type of exposure limits mean is available here - Workplace exposure limits for airborne contaminants | Safe Work Australia.While this list is extensive with many contaminants that may apply to grain growing businesses, some airborne contaminants of particulate note to grain growers include:There are other contaminants in this list that growers need to be aware of including crop-protection chemicals, chemicals and substances used for grain storage and other inputs (e.g. calcium carbonate), fuels, solvents and workshop products, and common airborne contaminants generated on farm (e.g. welding fumes).The 8-hour time weighted average (TWA) is the maximum average concentration of an airborne contaminant calculated for an eight-hour working day, based on a 5-day working week (40 hours). A worker must not be exposed to a level above the TWA over the course of an 8-hour working day with the intent of protecting most workers from long-term health effects of exposure to airborne contaminants.During daily work, a worker may be exposed to levels higher than the TWA for short periods, provided their overall exposure over the 8-hour working day remains lower than the TWA.Where workers have a working day longer than 8 hours, work more than 40 hours a week or have less than 16 hours between shifts, the PCBU may need to adjust the TWA to a lower exposure level. A lower exposure level is intended to protect workers who are working longer hours and have less recovery time between shifts. A TWA cannot be adjusted to a higher exposure limit for shorter shifts.Exposure limits for fumes and dusts (particulate contaminants) are written in milligrams of contaminant per cubic metre of air (mg/m3). When a WEL is given in both ppm (volume based) and mg/m3 (mass based), the ppm number should be considered exact and the mg/m3 used as a guide.Further to this, you need to be aware if the following is also listed for a contaminant on the WEL list, and comply with the associated requirements:peak limitation - the maximum or peak concentration of an airborne contaminant measured over the shortest time possible, and not exceeding 15 minutesSTEL - the time weighted average maximum concentration of an airborne contaminant calculated over a 15 minute period SWA have stated that PCBUs should consider engaging an appropriately trained and experienced person, such as an occupational hygienist, to understand the potential effect on worker’s health of airborne contaminants in their workplace and identify the control measures that may be needed to protect workers.The WEL list is available for download here - Workplace exposure limits for airborne contaminants | Safe Work Australia, which includes guidance from SWA. The actual list of WELs starts on page 12 of this document.

There has been significant discussion in the Australian grain sector about a couple of new WELs. In particular, the changes to exposure thresholds for phosphine and grain dust has been examined extensively in relation to the impact to growers and bulk handlers.Considering this, GPA have developed the following information to explain the changes related to phosphine and grain dust.GPA have also included some general guidance about the importance of other contaminants of the WEL list and the need for growers to be aware of them, and their broader responsibilities. PhosphinePhosphine is the most successful and cost-effective chemical fumigant available for killing all types of pests in stored grains and commodities.Sustaining the effectiveness and availability of phosphine is critical to the integrity and competitiveness of Australia’s post-harvest grain supply chain.The change in phosphine WEL has been extensively discussed within the grains sector and to state and federal safe work governments and regulators prior to the threshold change on 1 December 2026.This has primarily been due to the significant drop in exposure level (below), which would place significant limitations on its use and be extremely hard to measure with available equipment. There have also been queries about the justification behind this decrease.In light of these concerns, some states have delayed the implementation of the new WELs as follows:Victoria has delayed the implementation of 15 WELs, including phosphine, until 1 December 2029South Australia has determined there will be an 18-month extension for the new phosphine WEL to July 2028Western Australia announced a new deadline for changes to the WEL for phosphine until 1 December 2029 A phosphine best management guidance has been developed by the GRDC and is available here - Phosphine best management practices: Disinfesting stored commodities. This includes information on a variety of topics including workplace health and safety. Grain Dust (oat, wheat, barley)Grain growers have been concerned about the threshold change to ‘grain dust’, especially since it is inherent to grain production, and the new WEL is a significant decrease from the previous threshold (below).The workplace safety discussion related to airborne dusts has significant history in Australia and includes a wide range of different dust types. This includes examples of highly impactful dusts such as silica and asbestos which has led to national bans to protect Australian workers from potentially fatal effects.Workplace dusts are generally categorised into two main types:Inhalable dust (smaller than 100 micrometres) - visible dust which can affect your upper respiratory system (the nose, mouth, throat, or upper respiratory tract).Respirable dust (smaller than 10 micrometres) - dust particles not visible under normal lighting conditions. Their extremely small size also means they can be breathed deep into your lungs and lead to lung damage.Wheat, oats, and barley dust are considered to be respirable dusts.GPA are aware that grain growers have been concerned about the communication efficacy by regulators leading up to the WEL changes and what they may be required to do to comply with it.In October 2026 GPA conducted an online survey of growers that showed the following in relation to grain dust:91% of growers are concerned about their ability to reasonably measure, monitor and manage this change99% of growers do not know how they will measure the grain dust exposure in their business97% of growers do not know how they will manage this exposure limit change96% of growers do not know where to go to get more information about this changeOnly Victoria has delayed the implementation of the new grain dust WEL until 1 December 2029. Other WELsThere are a number of different WELs that may be relevant to grain growers. Considering this, growers should review the WEL list for contaminants that may be relevant to them.This includes crop-protection chemicals, chemicals and substances used for grain storage and other inputs (e.g. calcium carbonate), fuels, solvents and workshop products, and other common airborne contaminants generated on farm (e.g. welding fumes).An example of a contaminant that has not had an airborne contaminant threshold in the past that may be relevant to grain growers is Diesel Particulate Matter (DPM).Diesel fuel produces harmful emissions when not fully combusted, with exhaust from diesel engines more likely to produce harmful health effects than regular fuels due to a higher ignition point.The WEL list is available for download here - Workplace exposure limits for airborne contaminants | Safe Work Australia, which includes guidance from SWA. The actual list of WELs starts on page 12 of this document.

Your requirementsAs a ‘Person Conducting a Business or Undertaking’ (PCBU), you have a legal duty to eliminate or minimise the risks to health and safety from exposure to airborne contaminants for all persons at the workplace, as much as reasonably practicable.Exposure limits apply to all people in the workplace, including those not actively engaged in the work activity generating the airborne contaminant, such as other workers, customers, visitors, or members of the public.A ‘PCBU’ is a legal term in Australian Work Health and Safety (WHS) law referring to the primary duty holder responsible for ensuring worker health and safety. This can include companies, sole traders, partnerships, government bodies, and associations.‘Reasonably practicable’ in Australian WHS law means taking all measures to ensure health and safety that are possible and reasonable in the circumstances, balancing risk against the effort, time, and cost required to control it.From 1 December 2026, workplace regulations will require PCBUs to:ensure that no person at the workplace is exposed to a substance or mixture in an airborne concentration that exceeds the WEL for that substance.undertake air monitoring if they are not certain on reasonable grounds whether the airborne concentration of substance exceeds the WEL.The WEL list is available here (Workplace exposure limits for airborne contaminants | Safe Work Australia), noting there may be some variations between states for some substances like phosphine.Risk management involves thinking about what could happen if someone is exposed to a hazard (including substances in the WEL list) at your workplace and how likely it is to happen. To manage WHS risks (including airborne contaminants) you need to do the following in conjunction with your workers:Identify hazards - including substance you use that are on the WEL listAssess risks (e.g. undertake a risk assessment including how severe a risk is, if your control measures are effective, what action you should take to control the risk, and how urgently you need to act)Control risks (i.e. aim to eliminate risks, or minimise risks so far as is reasonably practicable)Review control measures to make sure they are working as planned To control risks, you can use a hierarchy of control measures (below). The hierarchy of control is a step-by-step approach to eliminating or reducing risks and ranks risk controls from the highest level of protection (elimination) and reliability through to the lowest and least reliable (PPE).To identify, assess, control and review risks, you can get advice and education from several different sources. This includes safe work agencies or appropriately trained and experienced professionals, including occupational hygienists, to understand the potential effect on worker’s health of airborne contaminants in the workplace and identify control measures that may be needed.Further information about this is available here - Identify, assess and control hazards - Managing risks | Safe Work Australia. ComplianceYou need to comply with safe work regulations in your workplace.There are different agencies responsible for safe work regulation in each state and territory, who are often responsible for a number of roles, including ensuring those with a duty of care fulfil their workplace safety obligations. This may include conducting workplace inspections, compliance audits, and responding to incidents that have exposed or caused injury to a person.Compliance and regulator activities and processes vary depending on the state or territory you are in. We have included links to the agency compliance pages under each state in the resource section of this webpage.A safe work regulator visit to your workplace will vary depending on the agency and the purpose of their visit; however, they may want to:inspect the workplacespeak to the manager/person in control of the workplace/workersreview your health and safety documentationspeak to you about identified hazards and the controls that you have in placeIn doing this, some information they may seek could include whether you have:identified and assessed the risks and hazards in your workplaceeffective control measures in place to manage risks, including to meet WEL thresholds, and what they are (this may be detailed in a hierarchy of control)reasonable grounds for believing the control measures are effective (including monitoring you have undertaken in your workplace, advice from an occupational hygienist, or information/data you have from another source) Depending on the outcome of a visit, there may be no formal action, or you may be issued with a notice that is intended to improve your practices. If an immediate or imminent serious risk to health and safety is identified, you may be directed to stop or cease an activity.Information about specific compliance and enforcement processes for your state are available from your states safe work regulator. Grain dust risk control management exampleExamples of different risk controls that a grower may use in relation to grain dust exposure management are detailed in the table below.These examples are illustrative and are not legal or occupational-hygiene advice. Each grower needs to develop risk management practices that align with their tasks, equipment, workforce, and jurisdiction.Please note, grain dust can also create fire and explosion risks, which require separate assessment and controls.

The following resources are links to specific information relevant to each state/territory, SafeWork Australia, GRDC, and other relevant information.This includes information and guidance related to areas such as agriculture/grains, WELs, legislation/regulation and contact details. Western AustraliaAgriculture - WorkSafe – LGIRSAirborne contaminants - WorkSafe – LGIRSDust and fibres - WorkSafe – LGIRSManaging health and safety - WorkSafe – LGIRSCompliance and prosecutions - WorkSafe – LGIRSPublications - WorkSafe – LGIRSLegislative framework - WorkSafe – LGIRSContact us - WorkSafe – LGIRS South AustraliaAgriculture | SafeWork SAAirborne contaminants | SafeWork SADiesel exhaust | SafeWork SAToolbox Safety Talks - Hazard identification and risk assessmentToolbox Safety Talks - Work health and safety responsibilitiesWHS Inspectors | SafeWork SAAdvisory Service | SafeWork SALegislation | SafeWork SAContact us | SafeWork SA VictoriaAgriculture | WorkSafe VictoriaGrains | WorkSafe VictoriaOHS responsibilities and duties | WorkSafe VictoriaWorkplace exposure standards and limits | WorkSafe VictoriaThe hierarchy of control | WorkSafe VictoriaWorkplace inspections | WorkSafe VictoriaLaws and regulations | WorkSafe VictoriaContact WorkSafe | WorkSafe Victoria QueenslandAirborne contaminants | WorkSafe.qld.gov.auAgriculture, forestry and fishing | WorkSafe.qld.gov.auHazardous dusts | WorkSafe.qld.gov.auCreating safe work | WorkSafe.qld.gov.auBusiness and employer responsibilities | WorkSafe.qld.gov.auCompliance and enforcement | WorkSafe.qld.gov.auResources | WorkSafe.qld.gov.auWork health and safety laws | WorkSafe.qld.gov.auContact | WorkSafe.qld.gov.au New South WalesAirborne contaminants | SafeWork NSWAgriculture, forestry and fishing | SafeWork NSWLegal obligations | SafeWork NSWCompliance and prosecutions | SafeWork NSWEasy WHS templates and glossary | SafeWork NSWLegislation | SafeWork NSWContact us | SafeWork NSW Australian Capital TerritoryWES/WEL Transition - WorkSafe ACTManaging safety - WorkSafe ACTEnforcement and prosecutions - WorkSafe ACTActs and regulations - WorkSafe ACTContact Us - WorkSafe ACT TasmaniaAgriculture, Forestry and FishingWorkplace Exposure Limits (WEL)Getting your safety systems rightEnforcement and prosecutionsActs and RegulationsContact us Northern TerritoryBusiness rights and responsibilities | NT WorkSafeWorkplace safety laws | NT WorkSafeInvestigations and enforcement | NT WorkSafeContact Us | NT WorkSafe SafeWork AustraliaAirborne contaminants | Safe Work AustraliaWorkplace exposure limits for airborne contaminants | Safe Work AustraliaGuide for PCBUs: Air monitoring and the workplace exposure limits for airborne contaminants | Safe Work AustraliaSafeWork Australia - Guide for Workplace Air MonitoringIdentify, assess and control hazards - Managing risks | Safe Work AustraliaHealth monitoring - Resources | Safe Work AustraliaAgriculture - Managing risks | Safe Work Australia Managing health and safety | Safe Work AustraliaLaw and regulation | Safe Work AustraliaResources and publications | Safe Work Australia GRDCPhosphine best management practices: Disinfesting stored commodities