# Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe, Division B: Substances

Extent: E+W+S+N.I.

Measurement of ozone precursor substances shall include at least nitrogen oxides (NO and NO2), and appropriate volatile organic compounds (VOC). A list of volatile organic compounds recommended for measurement is given below:
1-Butene
Isoprene
Ethyl benzene
Ethane
Trans-2-Butene
n-Hexane
m + p-Xylene
Ethylene
cis-2-Butene
i-Hexane
o-Xylene
Acetylene
1,3-Butadiene
n-Heptane
1,2,4-Trimethylebenzene
Propane
n-Pentane
n-Octane
1,2,3-Trimethylebenzene
Propene
i-Pentane
i-Octane
1,3,5-Trimethylebenzene
n-Butane
1-Pentene
Benzene
Formaldehyde
i-Butane
2-Pentene
Toluene
Total non-methane hydrocarbons

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Source: https://www.legislation.gov.uk/eudr/2008/50/annex/X/division/B (the official version)
Page: https://openlegislation.uk/eu-directive-2008-50/annex-X/division-B
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.