3. Salt concentrations.

Study	Intervention	Comparator
Arnold 2001	6.7 g/L NaCl dissolved in tap water	5.7 mg/L psoralen dissolved in tap water
Brockow 2007a	250 to 270 g/L NaCl present in natural spring water	no bath
Brockow 2007b	45 to 120 g/L NaCl present in natural spring water	no bath
Dawe 2005	150 g/L Dead Sea salt dissolved in tap water	no bath
Gambichler 2001	240 g/L NaCl dissolved in tap water	0.2 g/L present in tap water
Klein 2011	100 g/L Dead Sea salt dissolved in tap water	no bath
Leaute‐Labreze 2001	250 g/L NaCl present in natural sping water	no bath
Schiener 2007	250 g/L NaCL dissolved in tap water	0.5 mg/L psoralen dissolved in tap water

NaCl: sodium chloride