Standard Methods for monitoring and UK Approach

The European Commission, acting through the European Committee for Standardisation (CEN) has produced a series of Standard Methods for monitoring air pollutants. These documents outline minimum performance requirements for analysers, in order to ensure measurement methods comply with the Data Quality Objectives (DQO) set down in the Ambient Air Quality Directive (2008/50/EC) and in the amending Directive (EU) 2015/1480.

In 2005, after extensive discussion and research across the EU, a series of Standard Methods were published.  The current versions of these standards are listed below:

  • EN14211:2012 Nitrogen Oxides
  • EN14212:2012 Sulphur Dioxide
  • EN14625:2012 Ozone
  • EN14626:2012 Carbon Monoxide
  • EN12341:2014 PM10 and PM2.5
    (EN16450:2017 Automatic PM analysers)
  • EN14662-1:2005 and 14662-3:2015 Benzene

The Standard Methods are used as a template for instrument performance testing. The standards specify a series of tests and requirements for analysers to achieve based on both laboratory and field based studies. The results from these tests can then be used to calculate an uncertainty budget in order to show whether the instrument performance (in its' tested configuration) fulfills the DQO. This information can then be used as a stamp of approval for the use of specific analysers (in their tested configuration) in national monitoring networks. This process is known as Type Approval.

UK Type Approval of Gaseous Analysers: MCERTS

For gaseous analysers, the Type Approval testing process is managed in the UK by the Environment Agency under its MCERTS scheme with certification provided by SIRA the appointed certification body. The MCERTS Performance Standards mirror the requirements of the CEN Standard Methods and decisions are made by a certification committee. The relevant performance standard for gases is: Continuous Ambient Air Monitoring Systems (CAMS). UK testing against the standards began in 2005, and a number of instrument suppliers have successfully had their gaseous analysers Type-Approved under these schemes. Further details can be found at:

For measurements in the UK national network, the specific conditions and facilities at each site have been used to calculate measurement uncertainties for individual analysers. These results are published every six months and are available at:

UK Deployed Monitoring Methods

The techniques used for monitoring within the the UK’s national compliance monitoring network, the Automatic Urban and Rural Network (AURN) are summarised below. With the exception of the automatic PM10 analysers, the reference methods of measurement are defined in the relevant EU Directives.

AURN Measurement Techniques

O3 UV absorption
NO/NO2 Chemiluminescence
SO2 UV fluorescence
CO IR Absorption
PM10 and PM2.5
  • Tapered Element Oscillating Microbalance
  • Beta Attenuation monitor
  • Gravimetric monitor
  • Filter Dynamics Measurement System (FDMS)
  • Optical light scattering
  • Fine Dust Analysis System (FIDAS)

For particulate matter the AURN uses methods which have demonstrated equivalence to the reference method, but which (unlike the reference method) allow continuous on-line monitoring. More information is available on the Demonstration of Equivalence of PM Monitoring Methods page.