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THE PLANT AS AN INDEX OF SMOKE POLLUTION. 



By ARTHUR G. RUSTON, B.A., B.Sc. (London), D.Sc. (Leeds). 

 Lecturer in Farm Economics, The University, Leeds. 



(With Plates XXIV and XXV.) 



In an earlier communication 1 an account was given of investigations 

 carried out as to the nature and extent of atmospheric pollution by coal 

 smoke in and near an industrial town. These investigations were at first 

 limited to the area within a three mile radius of the centre of Leeds. 

 Later, subsidised by a Government Grant from the Development Fund, 

 they were extended to cover a wider area. 



The information thus obtained, as to the relative freedom or other- 

 wise of the various districts from pollution by coal smoke has been 

 exceedingly valuable in studying not only the effects of that pollution 

 on plant life, but also the ways in which the plant itself may be used as 

 an index of the amount of that pollution. 



1. In the first place the General Type of Vegetation in the smoke- 

 infested areas is instructive in drawing broad conclusions as to the 

 amount of smoke pollution. 



Certain plants have been found to be resistant, and others par- 

 ticularly susceptible to smoke damage; and the presence or absence of 

 some of these "Test Plants" is certainly suggestive. 



The evergreens, which have to withstand the winter smoke are 

 specially susceptible. Many of these in a smoke-infested area are quickly 

 killed ; -others first become deciduous, and then finally disappear. Among 

 the evergreens, the privet is particularly interesting as can be seen from 

 the notes summarised in the following table. 



Crowther and Ruston, Journal of Agricultural Science, vol. IV, Part 1. 



