ISO 17168-1:2025

Overview

ISO 17168-1:2025 defines a laboratory test method for evaluating the air‑purification performance of semiconducting photocatalytic materials under an indoor lighting environment, specifically for the removal of nitric oxide (NO). Intended primarily for fine ceramics and related materials (for example, titanium dioxide‑based coatings, ceramic plates, honeycomb substrates and composites containing ceramic microcrystals), this standard specifies how to expose a test piece to a model NO‑containing air stream under indoor light and quantify net NOx removal.

Key topics and technical requirements

• Scope and applicability: Applies to flat-sheet, board/plate, honeycomb and composite materials used in building and related applications. Excludes powders, granules and test pieces with excessive adsorption where equilibrium cannot be reached.
• Test principle: Continuous-flow photoreactor testing under defined indoor‑light irradiation. NO is adsorbed and oxidized on the photocatalyst surface to nitrate (and partly converted to NO2). Performance is reported as the net amount of NOx removed (NO removed minus NO2 formed), with adsorption/desorption and elution accounted for.
• Apparatus and gases: Requires a flow‑type photoreactor, controlled test gas (standard gas or zero‑calibration gas), pollutant analyzers (e.g., NO/NO2/NOx measurement), indoor light source meeting ISO 14605 / ISO 24448 requirements, and UV sharp cut‑off filters where applicable.
• Procedure elements: Test‑piece pretreatment, pollutant removal test under illumination, dark‑condition baselines, elution (washing) tests to measure nitrate formed on the surface, and calculations to separate adsorption, desorption and true photocatalytic removal.
• Analytical and quality controls: References analytical standards (e.g., ISO 7996 for NOx chemiluminescence, ISO 10304‑1 for anion analysis, ISO 10523 for pH) and laboratory competence requirements (ISO/IEC 17025).
• Limitations: Not suitable for measuring other photocatalyst attributes such as water contaminant decomposition, self‑cleaning, antifogging or antibacterial actions.

Practical applications and users

• Manufacturers and developers of indoor‑light‑active photocatalytic building materials (tiles, paints, panels, honeycombs).
• Independent testing and calibration laboratories seeking ISO/IEC 17025 compliance to certify NO removal performance.
• Product managers, architects and environmental consultants assessing material claims for indoor air quality improvement.
• Regulators and procurement teams specifying performance requirements for construction materials intended to mitigate NO pollution indoors.

Related standards

• ISO 22197‑1 (UV‑light photocatalytic NO removal - foundational method)
• ISO 14605, ISO 24448 (indoor light / LED light source specifications)
• ISO 7996 (NOx measurement by chemiluminescence)
• ISO 10304‑1 (anion determination by ion chromatography)
• ISO 10523 (water pH determination)
• ISO/IEC 17025 (laboratory competence)

Keywords: ISO 17168‑1:2025, fine ceramics, photocatalytic materials, indoor‑light, nitric oxide removal, air‑purification performance, titanium dioxide, photoreactor.