# The Air Quality Standards (Wales) Regulations 2007, Paragraph 3: Substances


Measurements of ozone precursor substances must include at least nitrogen oxides, and appropriate volatile organic compounds. For the purposes of this Schedule, “volatile organic compounds” means all organic compounds from anthropogenic and biogenic sources, other than methane, that are capable of producing photochemical oxidants by reaction with nitrogen oxides in the presence of sunlight.

---
Source: https://www.legislation.gov.uk/wsi/2007/717/schedule/10/paragraph/3 (the official version)
Page: https://openlegislation.uk/air-quality-standards-wales-regulations-2007/schedule-10/paragraph-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.