The author appears to be promoting quality designed electric saunas as the safest and most affordable type. Virtanen cautions about poisonous charcoal fumes or propane fumes from poorly operated or designed saunas of either type, and criticizes ineffectively designed electric stoves as well. Otherwise, he has many good things to say about the traditional wood heated sauna. Describing saunas in Siberia he writes "Log saunas throughout Russia are built of timber... a flat roof is made of turf over the round timbers." This reminds me of Alvar Aalto's sauna I encountered earlier while reading Nordskog's book. On page 125 is pictured an old shed roofed log sauna on the Karelian Isthmus that could easily be mistaken as a prototype for Aalto's design. The many black and white photos and pictures throughout the book are one of its best attributes.
Virtanen states a humidity of 1.20 ounces of water vapor by weight per pound of air is the technical suggestion, but offers a simple rule of thumb that anyone can gauge, somewhere between "dry" and "steamy" is best . He later writes :
The main requirement of the Finnish sauna is that it create bathing conditions which cause the bather to perspire freely. These conditions include the regulation of temperature, humidity and ventilation... The sauna should have an invigorating, rejuvenating, and tempering effect, while cleansing the body, refreshing the spirit and giving the feeling of complete well-being which is always the result of a good sauna.