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Characterisation Method Information
Characterisation Method Name:
HCI impact on severe morbidity
Date Completed:
Principal Method Name:
EPS: secondary aerosol pathway
Method Description:
Model for secondary aerosol pathway

The characterisation factor is determined by an equivalency method using PM10 as a
reference. The reason for using PM10 and not SO2 as a reference as in "HCI impact on YOLL" is that the main contribution to severe morbidity is from global warming while the main contribution to YOLL was direct exposure for PM10. For global warming effects the local exposure patterns is of less importance, and the easiest model was chosen.

Equivalency factor

An equivalency factor with PM10 could be determined through the formula:
MCl/MHCl * htrans * CPM10/CPM2.5 , where
MCl and MHCl are the molecular weights of Cl and HCl, respectively,

htrans is the transformation efficiency of HCl(g) to Cl - (s), i.e. what part of the HCl
entering the atmosphere that become particles (in the form of chlorides) and
C2.5 and CPM10 are the concentration of PM2.5 particles compared to that of PM10.

Many authors consider PM2.5 particles to be responsible for the impact found to correlate
with PM10 (Wilsson, 1996). As most of the sulphate particle mass consists of particles
less than 2.5 the ratio CPM10/CPM2.5 is used as an approximation for the enhanced potency of chloride particles.

CPM10/CPM2.5 has been determined in several studies. (Brook et al. 1997), (Haller et al.,
1999). Brook et al. studied the PM10/PM2.5 ratio at 19 sites in Canada between 1984 and
1993, Their average value, 1.89 will be used here. (For arid areas, the ratio increase, e.g. to 2.5) If particles are basic or non-acid, the transmission efficiency is very close to 1. If it would rain within that time, part of the HCl could be washed out without transformation to chloride particles. As much of the aerosol today is acid, htrans is probably less than 1, but
for reasons of simplicity the value 1 is still used.
Thus the equivalency factor is 35/36*1*1.89 = 1.84

Calculation of pathway specific characterisation factor

According to "PM10 impact on severe morbidity" there is - 2.33E-06 person-years/ kg PM10. We thus obtain -2.33E-06
*1.84 = -4.29E-06 person-years of severe morbidity per kg of HCl.
Literature Reference:
1. Wilson, R. and Spengler, J., “particles in Our Air: Concentration and health effects”, Harvard University Press, 1996, Harvard School of Public Health. 2. Haller, L., Claiborn, C., Larson, T., Koenig, J., Norris, G. and Edgar, R., (1999) “Airborne Particular Matter Size Distributions in an Arid Urban Area”, J. Air & Waste Manage. Assoc., Vol. 49, p. 161-168.
Methodological Range:
The system is global and the time period is 1990.

Existing Characterisation Factors of HCI impact on severe morbidity
Characterisation Parameter Category Indicator Impact Indication Principle Aspect Substance Quantity Unit Notes
CFactor Severe morbidity EPS/2000
Type = Emission
Direction = Output
Media = Air
Geography = *
HCl -4.29E-06 p yr/kg secondary aerosol pathway