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Characterisation Method Information
Characterisation Method Name:
NOx impact on Nuisance
Date Completed:
Principal Method Name:
EPS: secondary particles pathway and NO2 light absorption pathway
Method Description:
NO2 is a brown gas, which may be seen in stagnant weather conditions as a brown haze
over urban areas. Nitrogen oxides also transform to particles as nitrates in the same size range as the visible light wavelengths. Such particles scatter light very efficiently.

Model 1, secondary particles pathway
The characterisation factor is determined by an equivalency method using PM10 as a
Equivalency factor
In "NOx impact on severe morbidity" the equivalent factor was estimated to 1.0.

Calculation of pathway specific characterisation factor

The characterisation factor of PM10 for nuisance is 2.2810 -3 person-years/kg giving a characterisation factor for NOx of 2.2810 -3 person-years/kg NOx.

Model 2, NO2 light absorption pathway

The characterisation factor is determined by the empirical method.
Category indicator value in system considered
Brown haze is estimated to occur mainly in connection with ground level inversions and
heavy traffic. Such events occur in mainly in wintertime in northern latitudes, during a
few percent of the time. 2% is used as a first approximation. The number of persons
experiencing these episodes is estimated to 2 billion. Thus there will be 210 9 *0.02 =
410 7 person-years of nuisance.

Contribution to category indicators value from a flow unit

The brown colour of the haze is assumed to come from NO2, which is brown, while the
haze in itself and the visibility reduction is caused by particles. 50% of the nuisance is allocated to NO2 gas and the rest to the particles.
Using the anthropogenic NOx emission estimate mentioned in "NOx impact on severe morbidity" (153 tg/yr) the contribution will be 0.5* 6.5310 -12 = 3.2610 -12 per kg NOx.

Calculation of pathway specific characterisation factor

410 7 person-years of nuisance*3.2610 -12 per kg NOx = 1.3110 -4 person-years/kg NOx

Calculation of characterisation factor

2.2810 -3 + 1.3110 -4 = 2.4110 -3 person-years/kg NOx.
Literature Reference:
Steen B (1999b): A systematic approach to environmental priority strategies in product development (EPS). Version 2000 Models and data of the default method CPM report Chalmers University of Technology Sweden
Methodological Range:
The residence time in air in the order of a week. The flow group is emissions anywhere on the globe during 1990.

Existing Characterisation Factors of NOx impact on Nuisance
Characterisation Parameter Category Indicator Impact Indication Principle Aspect Substance Quantity Unit Notes
CFactor Nuisance EPS/2000
Type = Emission
Direction = Output
Media = Air
Geography = *
NOx 2.41E-03 p yr/kg 2 pathways