AIRBORNE BIOLOGICAL MATERIALS 



opportunities. This argues for a 

 small, volunteer steering group, rep- 

 resenting diverse interests in aero- 

 biology and dedicated to international 

 cooperation. This steering group 



should have membership from gov- 

 ernment, academic institutions, and 

 appropriate industrial organizations. 

 A large, monolithic research organi- 

 zation does not seem appropriate, but 



provisions must be made for receiv- 

 ing, processing, storing, and i 

 information, hopefully by a mode; 

 addition to some established data 

 center. 



Biological Monitoring Techniques for Measuring Aero-allergens 



Diseases caused by inhalation of 

 airborne biological particles have long 

 been recognized as important public 

 health problems. These diseases, 

 commonly termed hay fever or polli- 

 nosis, are estimated to affect about 

 10 percent of the U.S. population (a 

 much greater percentage than are 

 known to be medically affected by all 

 man-made air pollutants) and some- 

 times develop into more serious dis- 

 eases such as bronchial asthma. In 

 addition to causing considerable dis- 

 comfort to affected individuals, these 

 diseases cause a substantial economic 

 loss in terms of time lost from work 

 or school, lowered efficiency, and di- 

 rect medical costs. These diseases are 

 most frequently caused by pollens 

 from anemophilous plants and by a 

 few groups of fungus spores, but 

 other known or potentially allergenic 

 airborne biological particles include 

 spores from ferns and mosses, algae, 

 plant hairs, and insect scales. Aero- 

 allergens vary greatly in size, shape, 

 density, and other physical character- 

 istics, but many are more or less 

 spherical and most have dimensions 

 between 1 and 100 microns. 



Aeroallergens are commonly sam- 

 pled from the atmosphere to deter- 

 mine their presence or absence, 

 relative abundance, spatial distribu- 

 tion, and both seasonal and diurnal 

 patterns of occurrence. Past studies 

 have given considerable qualitative 

 information for a few common par- 

 ticles such as ragweed pollen, but few 

 data have been obtained for many 

 known or potential aeroallergens. 

 Until recent years, sampling devices 

 capable of giving a quantitative meas- 

 ure of concentration for particles in 

 this size class did not exist and even 



today are little used. However, ac- 

 curate concentration measurements 

 are necessary for such important 

 studies as the following: 



1. Determination of the spatial 

 and temporal changes in dis- 

 tribution of each important aer- 

 oallergen and the relationships 

 of such changes to meteoro- 

 logical and other factors. 



2. Studies of the relationships be- 

 tween aeroallergen concentra- 

 tions and the onset or severity 

 of allergic symptoms in suscep- 

 tible patients. 



3. Evaluating the success of medi- 

 cal treatments. 



4. Planning and evaluating the 

 results of weed control or eradi- 

 cation programs. 



5. Documenting changes in aero- 

 allergen concentrations caused 

 by changing land-use patterns 

 and urbanization. 



6. Determining the seasonal and 

 diurnal emission patterns from 

 sources of aeroallergens and 

 relating these patterns to other 

 variables. 



7. Determining the efficiency of 

 particle-removal mechanisms 

 such as washout by precipita- 

 tion and impaction by vegeta- 

 tion. 



8. Determining possible syner- 

 gistic effects between aeroaller- 

 gens and other air pollutants. 



Despite the obvious need for more 

 study of aeroallergens, such research 

 has been hindered by the difficulty of 

 obtaining accurate and representative 

 samples of these airborne particles 

 and by the tedious methods that 

 must be employed to identify and 

 count the samples collected. 



Evaluation of Current 

 Scientific Knowledge 



Nearly all research on aeroaller- 

 gens and their relationship to man 

 depends on sampling devices and 

 techniques, but the accuracy of such 

 sampling devices is critically depend- 

 ent on the characteristics of the par- 

 ticles they are employed to sample. 



Data Base — Information on the 

 characteristics of aeroallergens is far 

 from complete. Although the size 

 and shape of airborne pollens are 

 generally known, little useful infor- 

 mation exists on their density. The 

 size and density of some pollens are 

 known to change with age or with 

 changes in humidity, but few meas- 

 urements are available. For example, 

 it is not known whether the bladders 

 on conifer pollens are inflated or de- 

 flated while airborne or whether this 

 varies with conditions. Information 

 on fungus spores is more sparse; no 

 density determinations seem to have 

 been made, and many spores sampled 

 from the atmosphere cannot be iden- 

 tified as to source species. Even less 

 information is available on other ac- 

 tual and potential aeroallergens. 



The sources of airborne pollens are 

 generally known as to geographic re- 

 gion and habitat (see Figure X-9), 



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