I\r-NOTES ON THE SANITARY SIGNIFICANCE OF FORESTS.* 



By B. E. Ferxow. 



The subject of the sauitary significance of forests has been recently' 

 reviewed by Dr. E. Ebermayer, the well-known physicist at Muuich. 

 Otlier investigators have also contributed new material toward the 

 discussion of the subject. Especially the two Italians, Seratini and 

 Arata, investigated the intlueuce of forests on the quantity of micro- 

 organisms in the air, and Dr. Puchner investigated the contents of car- 

 bonic acid in the atmosphere under varying conditions. 



Eberniayer shows that the oxygen exhalation of a forest in propor- 

 tion to the consumption by man is insignificant. He figures that a 

 family of four persons would require for respiration, in the burning of 

 the necessary fuel, the oxygen exhaled by 2^ acres of forest. The hy- 

 geuic significance of ozone he doubts. Puchner shows that the air in 

 the forest contains generally more carbonic acid than the open, due to 

 decomposition of litter. On the other hand, Eberniayer shows the air 

 in the forest soil to contain less carbonic acid than that in the field soil,, 

 three fourths times less in winter and five-sixths times in summer; this. 

 is explained by differences in moisture conditions. But, like sea and 

 mountain air, forest air is freer from injurious gases, dust particles, and 

 bacteria. Furtherinore, the shade and the processes of assimilation 

 and transpiration have a cooling effect in summer, a warming effect in 

 winter, hence extremes in temperature are checked. Protection against 

 winds and extremes of temperature which the forest offers is cited as 

 desirable for the location of sanitaria and finally a tribute is paid to 

 psychic inriuence, and the liygienic significance of the forest is pro- 

 nounced as scientifically established. But of much more importance 

 than the air is shown the forest soil, especially since cholera, typhus, 



"These notes are based on the following publications: 



Dr. E. Eberniayer, in WoUny, 1890: (1) Hygienic significance of forest air anrl 

 forest soil. (2) Experiments regarding the signiticanco of liiiinus as a soil constit- 

 uent and influence of forest, different soils and soil covers on composition of the air 

 in the soil. 



Dr. H. Puchner: (1) Investigations of the carbonic acid contents of the atmos- 

 phere. 



Serafini and Arata : (1) Intorno all 'aziono dei boschi sui mikro organismi trans- 

 portati dai venti. 



171 



