cSuggested probable value based on data from the National Gallery and the literature, allowing a slight reduction to the indoors.
dMeasured in the Aula in the winter 2019.
eBased on  and the assumption that there will probably have been some reduction to the indoors.
fBased on evaluations of possible variations in the PM2.5 I/O ratio from the measured average ion I/O ratio in the Aula (Table 1) and the considerable general uncertainty.
gAverage of surface dry deposition velocity to paintings at RH = 30% and RH = 50% .
hA two times higher value (0.008 cm s−1) was reported from measurements  at RH = 30% than from RH = 50–90% (0.004 cm s−1) The value of 0.008 cm s−1 seems anomalous and it was decided to use the value of 0.004 cm s−1, for the situation with RH = 40% in the Oslo University Aula.
iObtained by modelling to measurements by [57, 58] report a typical value of 0.051 cm s−1 “based on studies by  and by ”
jAverage experimental dry deposition velocity to the indoor building surfaces of the historic house museum of Apsley House in London . Simulation of the mechanically ventilated room in the house (Waterloo Gallery) showed the same value