ISO 10121-3:2022

Overview

ISO 10121-3:2022 defines a practical classification system for gas-phase air cleaning devices (GPACDs) used to treat single-pass outdoor air supplied to general ventilation systems. It focuses on molecular (gaseous) contaminants found in urban and long-range polluted outdoor air and is intended to be used alongside particle-filtering standards such as ISO 16890-1. The standard does not apply to recirculation systems, indoor-source pollution control, or specialist sectors (pharmaceutical, microelectronics, nuclear, homeland security, military).

Key topics and technical requirements

• Reference pollutants: Four gases are specified for classification - ozone, sulphur dioxide (SO2), nitrogen dioxide (NO2) and toluene - chosen for relevance to outdoor urban and transboundary pollution.
• Duty levels and classes: For each pollutant the standard defines three duty levels (low, medium, high - LD, MD, HD) that reflect typical device performance ranges for the intended outdoor application.
• Dose concept: Performance is expressed as a relationship between dose (mass exposure) and removal efficiency; capacity is reported as E(%) versus D (g/m² or similar), enabling realistic lifetime/performance assessments.
• Test parameters and sequence: The document specifies test setup, conditioning, initial removal efficiency, capacity determination, integrated removal efficiency, and rules for desorption and retentivity.
• Reporting: Standardized test reporting elements and a classification graph example are included to support transparent specification and comparison.

Practical applications and users

ISO 10121-3 is designed to help stakeholders evaluate and select gas-phase filtration for outdoor air intake in buildings:

• Building owners and facility managers selecting ventilation filtration for urban locations
• HVAC designers and consultants specifying GPACDs for new or retrofit systems
• Manufacturers and suppliers of gas-phase media and devices for product classification and marketing
• Independent testing laboratories conducting standardized GPACD performance tests
• Procurement teams benchmarking products and comparing molecular filtration performance alongside particulate ratings (ISO 16890-1)

Benefits include clearer product comparison, improved specification matching for outdoor pollutant profiles, and better prediction of device service life under realistic exposure scenarios.

Related standards

• ISO 10121-1 - media test methods (interfaces between media suppliers and device producers)
• ISO 10121-2 - test methods for GPACDs (device-level testing)
• ISO 16890-1 - particle (particulate) air filter classification for general ventilation

Keywords: ISO 10121-3:2022, GPACD classification, gas-phase air cleaning, molecular filtration, outdoor air treatment, ozone, sulphur dioxide, nitrogen dioxide, toluene, duty levels, dose concept.