1. Ambient Air — Standard Method for the Measurement of the Concentration of Nitrogen Dioxide and Nitrogen Monoxide by Chemiluminescence;EN 14211,2012
2. Ambient Air — Method for the Determination of the Concentration of Nitrogen Dioxide by Diffusive Sampling;EN 16339,2013
3. DEFRA's LAQM Support web page: https://laqm.defra.gov.uk/diffusion-tubes/diffusion-tubes.html.
4. Equivalence Tool V3.1.xlsb, Implementation of ambient air quality legislation – Equivalence, https://ec.europa.eu/environment/air/quality/assessment.htm.
5. European Union Directive 20/50/EC - on Ambient Air Quality and Cleaner Air for Europe, Official Journal of the European Union, L 152/1 - 44, June 2008. https://eur-lex.europa.eu/legal-content/en/ALL/?uri=CELEX%3A32008L0050.