--- title: "ISO 23875 Limits: CO₂, PM4, Differential Pressure | Aethair" description: "ISO 23875 limits for mining cab air: CO₂, PM4, and differential pressure, with test conditions, who it applies to, and a recommended configuration." url: https://aethair.io/standards/iso_23875/ --- Compliance · ISO # ISO 23875: air quality control systems for operator enclosures Occupational: operator enclosures of mining and heavy machines **ISO 23875:2021** (amended in 2022), Mining — Air quality control systems for operator enclosures, sets performance requirements for the cabs of mining machines and the systems that keep their air clean. Clause 4.1 sets three requirements. Sustained cab CO₂ must stay **no more than 400 ppm above ambient** (a measure of ventilation). Respirable particulate must be **25 µg/m³ or less at the start and end of the standard's decay test, with a decay time of 120 seconds at most**. Cab pressurization must hold **between 20 Pa and 200 Pa** with the machine's electrical system on. It also requires an operator notification system for CO₂. [Schedule a call](https://calendly.com/d/ctdd-mkr-v9v/aethair-demo-website) [Configure ISO 23875 Monitoring](https://aethair.io/build/?params=co2,pm4,differential_pressure) At a glance **ISO** Occupational: operator enclosures of mining and heavy machines 3 parameters · 4 limit values [Carbon Dioxide (CO₂)](https://aethair.io/parameters/co2/) [PM4 (Respirable)](https://aethair.io/parameters/pm4/) [Differential Pressure](https://aethair.io/parameters/differential_pressure/) 2 devices measure them all - **Aethair PRO** Aethair CO₂ (dual NDIR) · Aethair Diff. Pressure - **Thiamis** TSI Particulate & Dust Monitors [Official text from ISO](https://www.iso.org/standard/77249.html) The standard ## What ISO 23875 Is The 25 µg/m³ figure is a test criterion rather than a standing in-cab limit. Gases and vapors outside the cab fall beyond the standard's scope. Limit values ## ISO 23875 Limit Values Every value ISO publishes for the 3 parameters below, with its averaging period, as the standard states it. [**Carbon Dioxide (CO₂)** Gases & VOCs](https://aethair.io/parameters/co2/) **400 ppm** *Sustained, above ambient* cab CO₂ no more than 400 ppm above ambient (clause 4.1) [**PM4 (Respirable)** Particulate Matter](https://aethair.io/parameters/pm4/) **25 µg/m³** *Decay test, start and end* respirable particulate; decay time 120 s at most [**Differential Pressure** Meteorology](https://aethair.io/parameters/differential_pressure/) **20 Pa** *Minimum, sustained* cab pressurization with the machine's electrical system on **200 Pa** *Maximum* cab pressurization Who it applies to ## Who Uses It Mine operators and machine manufacturers specifying and verifying cab air quality control systems. It was written by ISO's mining committee, but its design and test requirements are written to be universal, for fixed and mobile operator enclosures alike. A revision is in preparation at ISO. Monitoring ## How Monitoring Supports It The requirements are measured inside the cab: CO₂ against the ambient level, cab pressure, and particulate during testing and in service. A monitor in each cab that records CO₂, differential pressure, and particulate continuously shows whether filtration and pressurization hold while the machine works, and flags a loaded filter or a failed seal across a fleet. [Customize this configuration](https://aethair.io/build/?params=co2,pm4,differential_pressure) ### Who measures each parameter | Parameter | Aethair PRO | Aethair IAQ | External | | - | - | - | - | | [Carbon Dioxide (CO₂)](https://aethair.io/parameters/co2/) | CO₂ (dual NDIR), CO₂ (self-calibrating NDIR) cartridges | Built in | [2 instruments](https://aethair.io/parameters/co2/) via Thiamis | | [PM4 (Respirable)](https://aethair.io/parameters/pm4/) | — | — | [2 instruments](https://aethair.io/parameters/pm4/) via Thiamis | | [Differential Pressure](https://aethair.io/parameters/differential_pressure/) | Diff. Pressure cartridge | — | — | Devices ## Devices That Cover ISO 23875 How much of this standard one Aethair monitor covers, followed by the third-party instruments in the sensor catalog that measure its parameters. Each connects to Environet through a Thiamis gateway, which adds whatever the monitor leaves out. Aethair monitors [**Aethair PRO** Built in + Aethair CO₂ (dual NDIR), Aethair Diff. Pressure 2 of 3: CO₂, Differential Pressure](https://aethair.io/products/pro/) Covers part of it (combine on one Thiamis) [**TSI DustTrak** Particulate & Dust Monitors 1 of 3: PM4](https://aethair.io/sensors/tsi-particulate-dust-monitors/) [**Particles Plus** Particulate & Dust Monitors 1 of 3: CO₂](https://aethair.io/sensors/particles-plus-particulate-dust-monitors/) [**RAE** Gas Detectors 1 of 3: CO₂](https://aethair.io/sensors/rae-gas-detectors/) [**Trolex** Particulate & Dust Monitors 1 of 3: PM4](https://aethair.io/sensors/trolex-particulate-dust-monitors/) Solutions ## Solutions Judged Against ISO 23875 ### [Cabin Air Quality](https://aethair.io/solutions/cabin-air/) Respirable dust, gases, and blast monitoring [All solutions](https://aethair.io/solutions/) Questions ## ISO 23875 FAQ What does ISO 23875 require for cab air? Sustained cab CO₂ no more than 400 ppm above ambient, respirable particulate of 25 µg/m³ or less at the start and end of the decay test (with a decay time of 120 seconds at most), and sustained pressurization between 20 Pa and 200 Pa. Is 25 µg/m³ a limit for the air in the cab? No. It is the particulate level at the start and end of the standard's decay test, not a standing limit for cab air during operation. Does ISO 23875 cover gases such as CO? No. Gases and vapors outside the cab fall beyond its scope, so a mine monitors them under its own rules.