European characterization factors for damage to natural vegetation by ozone in life cycle impact assessment

Spatially explicit characterization factors (CFs) for tropospheric ozone damage on natural vegetation caused by anthropogenic NOx and NMVOC emissions are presented for 65 European regions. The CFs were defined as the area-integrated increase in the potentially affected fraction (PAF) of trees and grassland species due to a change in emission of NOx and NMVOCs. The CF consists of a Fate Factor, quantifying the relationship between the emission of precursor substances and ozone exposure, and an area-integrated Effect Factor, quantifying the relationship between ozone exposure and the damage to natural vegetation. The relationships describing the ecological effects of a pollutant were based on a lognormal relationship between the PAF and ground level ozone concentration. We found higher CFs for NOx compared to NMVOC, and these were largest in south European regions. Furthermore, we found that both the fate factor and effect factor contribute to the spatial differences found in the CFs. Our study shows that effects caused by ozone exposure from NOx emissions are larger than those of acidification caused by NOx, indicating the importance of including ozone effects to natural vegetation in life cycle assessment studies.