Regulations 2, 9(15)
SCHEDULE 6MEASUREMENTS OF OZONE PRECURSOR SUBSTANCES
Objectives
1.1 The main objectives of measurements of ozone precursor substances are to analyse any trend in ozone precursors, to check the efficiency of emission reduction strategies, to check the consistency of emission inventories and to help attribute emission sources to pollution concentration.
An additional aim is to support the understanding of ozone formation and precursor dispersion processes, as well as the application of photochemical models.
Substances
1.2 Measurements of ozone precursor substances must include at least nitrogen oxides, and appropriate volatile organic compounds (VOC). A list of volatile organic compounds recommended for measurement is given below.
| Ethane | 1-Butene | Isoprene | Ethyl benzene |
| Ethylene | trans-2-Butene | n-Hexane | M+p-Xylene |
| Acetylene | cis-2-Butene | i-Hexane | o-Xylene |
| Propane | 1.3-Butadiene | n-Heptane | 1,2,4-Trimeth. Benzene |
| Propene | n-Pentane | n-Octane | 1,2,3-Trimeth. Benzene |
| n-Butane | i-Pentane | i-Octane | 1,3,5-Trimeth. Benzene |
| i-Butane | 1-Pentene | Benzene | Formaldehyde |
| 2-Pentene | Toluene | Total non-methane hydrocarbons |
Reference methods
1.3 The reference method for the analysis of oxides of nitrogen shall be ISO 7996:1985, Ambient air – determination of the mass concentrations of nitrogen oxides – chemiluminescence method
Siting
1.4 Measurements should be taken in particular in urban and suburban areas at any monitoring site set up in accordance with the requirements of these Regulations and considered appropriate with regard to the monitoring objectives in this Schedule.