CWA 18408:2026

This document establishes a refined protocol for indoor exposure investigation to ultrafine particles (UFP; diameter < 100 nm).
The protocol comprises a two-step approach through information gathering and on-site measurements (1. defining the requirements for structuring a scoping questionnaire and 2. use of portable measurement equipment for ultrafine particles). The described approach extends from the direct measurement of UFP as outlined in the bibliography and ISO 16000 series by calculating the UFP via a set of different PM monitoring devices, potentially minimising the individual drawbacks and limitations of individual measuring systems and delivering the UFP concentrations in the indoor space. Where regulatory or compliance measurements are required, relevant ISO 16000 standards apply.
This protocol applies to different indoor settings, including offices, schools and universities, hospitals and care centres, dwellings, and public transport vehicles.
This protocol is not intended to be used in laboratories and industrial settings, which are covered by other existing CEN and ISO Standards, and it does not provide suggestions for exposure threshold values.