Characterisation Method Name: 
N2O impact on YOLL 
Version: 
1999 
Date Completed: 
1999 
Principal Method Name: 
EPS: global warming pathway and secondary NOx pathway 
Method Description: 
YOLL stands for Year of Lost Life. Model 1, global warming pathway The characterisation factor is determined by an equivalency method using CO2 as a reference. The global warming potential for N2O on a 100 years basis is 320 (IPCC 1994). The characterisation factor of CO2 for YOLL is determined in CO2 impact on YOLL to 7.93E–07 YOLL/kg CO2. Therefore the characterisation factor of N2O for YOLL is 320*7.93E–07 = 2.54E–04 YOLL/kg N2O. Model 2, secondary NOx pathway The characterisation factor is determined by an equivalency method using NOx as a reference. The transformation to nitrogen oxides and further to particles is difficult to model. However as a start and for this version of the EPS default method, 50% is assumed to be transferred to NOx and the resulting contribution to the category indicators are calculated using the NOx models. The other 50% of the N2O is assumed to be transformed to N2. At 50% conversion efficiency 1 kg of N2O will give 0.5*2*46/34 =1.35 kg NOx (NO2). The characterisation factor of NOx for YOLL is determined in NOx impact on YOLL to 2.45E05 YOLL/kg NOx. Therefore the characterisation factor of N2O for YOLL is 1.35*2.45E–05 = 3.31E–05 YOLL/kg N2O. Calculation of characterisation factor The total characterisation factor is thus 2.54E–04 + 3.31E–05 = 2.44E–04 YOLL/kg N2O. 
Literature Reference: 
1. Houghton, J.T Jenkins, G.J. and Ephraums, J.J., (Ed.) (1990) Climate change – The IPCC scientific assessment. Cambridge University Press 2. IPCC, “The 1994 Report of the Scientific Assessment Working Group of IPCC. Summary for policymakers”, WMO and UNEP, 1994 
Methodological Range: 
The impact is of global character. The modelled system is therefore global. The temporal system borders are 100 years (19902090). The society effected is the one described in IPCC scenario IS92A. (IPCC, 1990). 
Notes: 
Characterisation Parameter  Category Indicator  Impact Indication Principle  Aspect  Substance  Quantity  Unit  Notes  
CFactor  YOLL  EPS/2000 

N2O  2.44E04  p yr/kg  2 pathways 