Ambient air - Guide for the measurement of elemental carbon (EC) and organic carbon (OC) deposited on filters
This Technical Report gives guidance on the measurement of elemental carbon (EC) and organic carbon (OC) following the requirement for the networks of all EU member countries to measure EC and OC in particulate matter from June 2010 at background sites according to the Council Directive 2008/50/EC on ambient air quality and cleaner air for Europe.
The Technical Report describes the analytical procedures for determining EC and OC on quartz fibre filters as µg/cm2, and the subsequent calculation of concentrations as µg/m³. Sampling onto filters is to be done in accordance with EN 14907 for PM2,5. The sampling process determines the size fraction of the particulate matter, the retention of semi-volatile material, and ab/desorption of volatile organic compounds on the filter at the time of sampling.
The same analysis method may also be used for other size fractions. Any possible additional artefacts e.g. due to charring or higher concentrations of carbonates would need to be assessed in those cases.
The measurement procedures are applicable for:
- rural background,
- urban background,
- road side and
- industrial sites.
The scope includes non rural site measurements, to allow the assessment of additional exposure of people in urban areas as stated in the objectives of the council directive and to achieve coherence in the European approach. Measurements are made over a nominal sampling period of 24 h, and concentrations are expressed as µg/m³, where the volume of air is the volume at ambient conditions near the inlet of the sampler at the time of sampling.
The applicable concentration range of the proposed method is limited by the optical correction, instrument, and thermal protocols applied in the analysis of EC and OC. Therefore no definitive values can be given. The experience from EMEP shows the applicability of the method at regional background sites.