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Characterisation Method Information
Characterisation Method Name:
CO impact on Nuisance
Date Completed:
Principal Method Name:
EPS: empirical method
Method Description:
The characterisation factor is determined by an empirical method .

At 10 - 20 mg/m 3 there is a statistically significant decrease (3-7%) of the relation work time to exhaustion in healthy young men. This effect is assigned to the nuisance impact category.

1.2 billion people live in urban OECD areas and 1.4 billion in urban areas in non-OECD
countries. WHO criteria for CO is estimated to be exceeded in almost 50% of the cities
(see results from GEMS/ UNEP/WHO report "assessment of urban air quality"
1988). It is likely that only a part of the population in these cities is exposed. In a Swedish study (Steen, 1991) the ratio between the maximum and population-weighted average concentrations in three cities were estimated. Ratios between 0.4 and 0.7 were found depending on the urban geography and regional background. According to another UNEP/WHO study about air pollution in the megacities in the world (1992) the major
problems occur in cities in countries where the economy has started to expand recently,
like Seoul and Sao Paulo. These cities have had a heavy increase in the use of cars but
not yet enforces catalytic converters. In Tokyo, the situation has improved quite
significant since the introduction of catalytic converters. This would indicate that the part of the population, which is overexposed, is clearly less than half. This part is assumed to consist of those who work or live permanently in the centre of the cities, roughly less than a third of the population. This means that about 0.4 billion people would be exposed to more 10 mg/m 3 during more than 8 hours.

Considering the fact that most of the overexposed are in developing countries having a greater part of the population in physical exercise, 10% of the population which experiences concentrations above the WHO recommendations is assumed to be effected. Critical levels are assumed to be exceeded during 1% of the time. (99%-ile or 10 cases per year of exceedence of the 8-hour mean) The population exposure to more than 10 mg/m 3 expressed in number of person-years is then approximately 400 000 person-years.

Global emissions of CO are 2600 million tons. Man made emissions account for 1600 million tons (UNEP/GEMS Env. Library No 4, 1991. The contribution from 1 kg CO is at an average 1/(1600·10 9 ) = 6.25E-13 .

A characterisation factor for the global average of nuisance would thus be 400 000*6,25E-13 = 2.50E-07 person-years per kg of CO.
Literature Reference:
Steen, B., (1991) “Sveriges befolknings exponering för kväveoxider och mutagena ämnen i luft (Exposure of the Swedish Population to Nitrogen Oxides and mutagens in air)”, Swedish Environmental Research Institute, Report B 1033, September 1991. (In Swedish)
Methodological Range:
The system is urban and global and during the year 1990.

Existing Characterisation Factors of CO 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 = *
CO 2.50E-07 p yr/kg