An addition to the requirements of Paragraph 1.3. of Appendix 8 to Annex 4, the following requirements shall apply:

Non-methane hydrocarbon concentration is calculated as follows:

C_NMHC = C_THC — (Rf _CH4 × C_CH4)

where:

C_NMHC

corrected concentration of NMHC in the diluted exhaust gas, expressed in ppm carbon equivalent,

C_THC

concentration of THC in the diluted exhaust gas, expressed in ppm carbon equivalent and corrected by the amount of THC contained in the dilution air,

C_CH4

concentration of CH₄ in the diluted exhaust gas, expressed in ppm carbon equivalent and corrected by the amount of CH₄ contained in the dilution air,

Rf _CH4

is the FID response factor to methane as defined in paragraph 2.3 of Annex 4-Appendix 6.