Table 1.

Variables in the PFM-induced facial thermal load model (S_PFM).

	Symbol	Unit	Source
Outside the PFM
●Ambient air temperature	Ta	°C	Measured
●Ambient relative humidity	RHa	%	Measured
●Density of air	ρ	kg/m3	Measured
●Heat capacity of air	cp	kg⋅m2⋅s−2⋅K−1	Measured
●Sensible heat flux	H	W/m2	Calculated
●Net radiation	Rn	W/m2	Calculated
●Latent heat flux	LE	W/m2	Calculated
Inside the PFM
●Air temperature inside PFM	Tin	°C	Measured
●Relative humidity inside PFM	RHin	%	Measured
●Facial skin temperature	Tfsk	°C	Measured
●Facial skin wettedness	w	–	Measured
●Convection via facial skin	Cfsk	W/m2	Calculated
●Evaporation via facial skin	Efsk	W/m2	Calculated
●Radiation via facial skin	Rfsk	W/m2	Calculated
●Convection via respiration	Cres	W/m2	Calculated
●Evaporation via respiration	Eres	W/m2	Calculated
●Conduction from PFM surface	Gpfm	W/m2	Calculated
●Heat loss from leakage	Q	W/m2	Calculated
●Heat flux from facial skin	Hfsk	W/m2	Measured
PFM parameters
●Albedo of PFM surface	apfm	%	Measured
●Dead space volume	Vpfm	m3	Measured