ILCD Handbook: Framework and requirements for LCIA models and ...

ILCD Handbook: Framework and requirements for LCIA models and indicators First edition
emissions of SO2 and NOx that create sulphate and nitrate aerosols. Particulate matter is
measured in a variety of ways: total suspended particulates (TSP), particulate matter less
than 10 microns in diameter (PM10), particulate matter less than 2.5 microns in diameter
(PM2.5) or particulate matter less than 0.1 microns in diameter (PM0.1).
The characterisation factor (CF) for particulate matter/respiratory inorganics accounts for
the environmental fate (F), exposure (X), dose-response (R) of a pollutant for midpoint
factors, and of severity (S) for endpoint factors (Humbert et al., 2008a). See below:
CF = S R X F = EF iF
The pollutant can be a single chemical (e.g. CO) or group of agents (e.g. PM2.5). The fate
factor relates the emission flow to the mass in the air. The exposure factor determines the
change in intake rate per change in mass in the environment. The dose-response slope
relates the change in intake with the marginal change in morbidity and mortality cases and
the severity is the change in damage per morbidity and mortality case.
The fate and exposure can be combined into an intake fraction (iF) (Bennett et al., 2002).
The dose-response and the severity can be combined into the effect factor (EF, in
DALY/kginhaled).
The intake fraction describes the fraction of the emission that is taken in by the overall
population. Intake fractions can be calculated using fate and exposure models. For the case
of particles, it is possible to characterize the fate and exposure further in the cause-effect
chain by an intake factor (van Zelm et al., 2008) or even an uptake factor (Humbert and
Horvath, 2008) because:
1. The exposing particle can be different from the emitted particle (e.g., secondary
PM from precursors);
2. The influence of the changing particle size distribution (PSD) throughout time
through phenomena like coagulation and nucleation can render the metric of the
intake fraction, only a partial representation of exposure.
. However, since these two metrics are not yet widespread and not used for other toxic
impacts, the metric of the intake fraction is recommended to be used.
Several studies suggest that no thresholds for PM10 should be assumed in the effect
calculations (World Health Organization, 2004). Thus it is recommended to derive doseresponse
from epidemiological studies assuming linear slopes. However, while the influence
of this assumption is unclear based on analogous insights for toxicity effects (e.g. Crettaz et
al.), it is necessary to stress that the linear dose-response assumption is not well accepted
for the high concentrations found in developing countries.
For respiratory inorganics, all available methods are de facto endpoint methods. It is
advised to report both the number of cases of different diseases as well as the related Years
of Life Lost, Years of Life Disabled and DALYs.
4.4.1.1 Environmental Mechanism (cause-effect chain)
Figure 4-5 presents the cause-effect chain of respiratory impacts caused by inorganics
and corresponds to the framework of fate, exposure, and effect assessment.
4 Requirements for specific impact categories 44