Metrology for Chemical Pollutants in Air

This  project addressed the need to assess the quality of outdoor and indoor air. The European Air Quality Directive (2008/50/EC) sets challenging limit values and data quality objectives for the measurement of pollutants in ambient air and air monitoring networks have struggled to comply with the objectives because of the lack of metrological transfer standards at and below the pollutant limit values specified. In addition, governments are starting to address the quality of indoor air where harmonised regulation does not exists.

The EMRP project developed:

• Preparation methods for calibration gases for the pollutants SO2, NO and NO2 at or near the limit values of the regulation.
• A certified protocol for preparation and validation of ‘zero gas’ for zero-ing analytical instrumentation. This is essential for measurements of pollutants at very low concentrations. 
• Reference methods and reference materials for harmful (semi-) volatile organic compounds ((S)VOCs), which originate from emissions from building materials and contaminate indoor air. Preparation methods for (S)VOC transfer standards at levels of interest for emission testing laboratories were validated and a reference material reproducing the gas emission behaviour typical of a construction product was developed for the quality control of emission test chamber measurements.
• Innovative micro-sensors for air quality monitoring based on graphene. Two types of graphene sensors were tested for the measurement of ambient levels of NO2 and a protocol for the evaluation of micro-sensors was developed and implemented. A clustered system of micro-sensors, was developed and evaluated as a potential cost-effective method for the measurement of pollutants under the Air Quality Directive. It demonstrated that an artificial neural network of calibrated sensors achieved the best accuracy.

The new traceable measurement capabilities will improve comparability of data between the air quality reference laboratories responsible for quality assurance and quality control of the air monitoring networks in each country. The project worked with members of the European Network of Air Quality Reference Laboratories (AQUILA) throughout the project to understand their needs and share the research outputs. The new calibration facilities and tools are being trialled in air quality networks in Switzerland and it is expected that the zero-gas protocol will be incorporated in an amended ISO standard for gas purity.  

EMPIR project 15SIP01 Zero Gas builds on this work.