DIN EN 16976:2024-09

This document describes a standard method for determining the particle number concentration in ambient air in a range up to about 10⁷ cm^-3 for averaging times equal to or larger than 1 min. The standard method is based on a Condensation Particle Counter (CPC) operated in the counting mode and an appropriate dilution system for concentrations exceeding the counting mode range. It also defines the performance characteristics and the minimum requirements of the instruments to be used. The lower and upper sizes considered within this document are 10 nm and a few micrometres, respectively. This document describes sampling, operation, data processing and QA/QC procedures including calibration parameters. The WHO recommends measuring ultrafine particles in ambient air. As a guideline it classifies values < 1 000 cm^-3 (24-hour average) as "low" concentrations and values > 10 000 cm^-3 (24-hour average) and 20 000 cm^-3 (1-hour average) as "high" concentrations. The recommendation to measure ultrafine particles at selected locations will also be included in the European Air Quality Directive 2008/50/EC, which is currently being revised. This document is intended for measuring device manufacturers, environmental authorities, research institutes, and operators of air quality monitoring networks. The responsible national standardization committee is Subcommittee NA 134-04-02-18 UA "Measurement of particles in ambient air - Determination of the particle number concentration" at VDI/DIN-Commission on Air Pollution Prevention (KRdL) - Standards Committee.