The literature on the influence of atmospheric pollutants on paper per
manence shows that the absorption of sulfur dioxide by paper depends o
n many factors. There is limited work on the effect of nitrogen dioxid
e on paper permanence. No data exists on the effect of ozone. Work on
mixtures of gases is scarce. There is almost no literature on the rela
tionship between the amount of pollutant gas absorbed and the strength
loss of paper.