The methodology of quantitative risk assessment studies

Table 1 A series of 10 scenarios compared in a risk assessment study of the impact of atmospheric pollution (fine particulate matter, or PM_2.5). From [40]

Scenario number	Scenario description	Scenario name	PM_2.5 yearly level reduction
S1	Spatially homogeneous target value in the whole area	“WHO guideline”	Down to WHO yearly guideline (10 µg/m³ at the time of this publication)
S2		“No anthropogenic PM_2.5 emissions”	Down to lowest nation-wide levels (4.9 µg/m³)^a
S3		“Quiet neighborhood”	Down to lowest study area district levels (10th percentile of exposure)^b
S4	Homogeneous PM_2.5 decreases in the whole area	“-1 µg/m³”	Baseline^c -1 µg/m³
S5	Homogeneous PM_2.5 decreases in the whole area	“-2 µg/m³”	Baseline^c -2 µg/m³
S6	Targeted reduction in PM_2.5-related mortality in the whole area^d	“-1/3 of mortality”	Equivalent to decreasing homogeneously and sufficiently the baseline^c exposure to achieve the indicated health objective^e
S7		“-1/2 of mortality”
S8		“-2/3 of mortality”
S9	2008/50/EU Directive^f “2020 target”	In the whole study area”	Baseline^c -15%
S10	2008/50/EU Directive^f “2020 target”	Restricted to PM_2.5 exposure hotspots”	Baseline^c -15%, only if baseline ≥ 90th centile of PM_2.5 levels^g

^aCorresponding to the 5th percentile of PM_2.5 concentration distribution among French rural towns
^bThe 10th percentile of PM_2.5 exposure by Housing Block Regrouped for Statistical Information (IRIS) in the study area (corresponding to 10.3 and 12.4 µg/m³ in Grenoble and Lyon conurbations, respectively)
^cBaseline corresponds to the PM_2.5 exposure average for the 2015–2017 period, taken as a reference in the present study
^dMortality reduction targets expressed as a proportion of the non-accidental death cases attributable to PM_2.5 exposure that can be prevented under the scenario S2: “No anthropogenic PM_2.5 emissions”
^eS6: -2.9 and -3.3 µg/m³ in Grenoble and Lyon conurbations, respectively; S7: -4.4 and -5.1 µg/m³; S8: -6.0 and -6.9 µg/m3
^fInspired by the 2008/50/EU Directive, which targets relative PM_2.5 yearly average decreases to obtain by 2020. The decrease value depends on the exposure average for the last three years (2015–2017): -15% in the case of Grenoble and Lyon conurbations
^gThe 90th percentile corresponded to 16.0 and 17.4 µg/m³ in Grenoble and Lyon conurbations, respectively

ISSN: 1476-069X