Pilot Study: Comparison of nitrogen dioxide gas standards - Optical and gravimetric method
Project Description
Nitrogen oxides (NOx) emissions have been regulated by both road and non-road sectors [1] [2]. Nitrogen dioxide (NO2) is a major component of NOx and an important pollutant which has negative effects on air quality and human health [3] [4]. Due to its reactivity and the difficulty to develop and disseminate stable reference gas standards, it has also been spotlighted and continuously being studied in the metrology community.
There were two key comparisons conducted in 2009 and 2018 respectively: CCQM-K74 and CCQM-K74.2018. The comparisons were at 10 µmol/mol NO2 in N2. Some issues were observed in the CCQM-K74.2018 comparison (e.g. inconsistent behaviour of NO2 decay in different cylinders). A follow-up comparison (BIPM.QM-K6) is planned at 10 µmol/mol NO2 in N2.
The aim of this comparison study is, firstly, to evaluate the level of comparability of a newly developed optical NO2 standard and a classical reference material-based NO2 standard. Secondly, to prepare and support the participants for potential participation in future comparisons (e.g. BIPM.QM-K6). The yet to be defined comparison protocol will be designed as a bilateral comparison.
[1] No 2017/1151 of 1 June 2017 supplementing Regulation (EC) No 715/2007 of the European Parliament and of the Council on type-approval of motor vehicles with respect to emissions from light passenger and commercial vehicles (RDE3). https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32017R1151.
[2] Revised MARPOL Annex VI: Regulations for the Prevention of Air Pollution from Ships and Nox Technical Code 2008. (2009). ISBN: 978-9280142433.
[3] European Environment Agency, González Ortiz, A., Guerreiro, C. and Soares, J., Air quality in Europe – 2020 report, Publications Office, 2020, https://data.europa.eu/doi/10.2800/786656.
[4] WHO global air quality guidelines. Particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Geneva: World Health Organization, 2021. Licence: CC BY-NC-SA 3.0 IGO
The technical protocol can be downloaded here>>