Sectoral shares of tropospheric ozone precursors (energy and non-energy components) in total emissions, EU-27.

The emissions of ozone precursors (NOx, NMVOC, CO and CH4) are each weighted by an ozone formation factor prior to aggregation to represent their respective ozone forming potentials. The relative impact of the combined contribution of NOx, NMVOC, CO and CH4 to ozone formation can be assessed based on their tropospheric ozone forming potentials (TOFP): nitrogen oxides 1.22, non-methane volatile organic compounds 1.0, carbon monoxide 0.11 and methane 0.014.