Table 7. Properties of parameters uncertainty.

Authors' priority	Parameter	Symbol	Uncertainty vs. Variability	Generality	Researchable	Percentage in the top 3 uncertainty parameters among retrospective scenario (%)+	Percentage in the top 3 uncertainty parameters among prospective scenario (%)+
High	Mass transfer fraction from surface to hand	fsh	Both	Similarities expected	Yes	0	33
High	Dose-response coefficients	k	Both	Pathogen specific	Difficult	13	20
High	Resuspension rate	μ2	Both	Similarities expected	Yes	0	20
High	Hand-surface contacting rate	rhs	Both	Similarities expected	Yes	0	13
Moderate	Decay rate on fomite	γf	Both	Pathogen specific	Yes	7	13
Moderate	Decay rate in the air	γair	Both	Pathogen specific	Yes	13	0
Low	Breathing rate	Inh	Variability	Common across pathogen	Yes	33	0
Low	Air change rate	ACH	Variability	Common across pathogen	Yes	20	0
Low	Density of the particle	ρp	Variability	Common across pathogen	Yes*	13	0

^*Density can readily be measured but it is not clear that laboratory values could reflect density in an actual release.

⁺The percentages in the retrospective scenario are based on inhalation risk in the retrospective scenario, while the percentages in the prospective scenario are based on ingestion risk in the prospective scenario of Table 6.