2h-hour samples per day. Similarly, isolated collections of activity appear in areas distant from those affected by airborne debris. Such errors indicate the caution which should be exercised in examining individual values. The emphasis, rather, should be on the broader aspects where the presence of corroborating - information lends credence to the individual samples. DEPOSITION L. va 1.5.1. Bry Fallout , | It dg Mikely that the gumed paper collects more activity than remains on the ground in periods of dry weather when the wind cam pick up debris which has already fallen out. This is especially true in dusty locations. The effect of rain running or ¢ splattering off ‘the gummed paper and carrying with it some debris and soluble ratioactive material, must be important, but no information is available on this subject. It is believed that more debris will be lost in the heavy tropical showers thm in lighter steady rains of the temperate latitudes. ink wr 1.5.2 ‘Retnout 1.5.3 Effect ofthe Particulate Nature of Debris If activity is concentrated on a relatively amal? mumber of large particles, it is possible that the small area - sampled by the gummed paper may not be a statistically signifi- cant sample. The duplicate papers, exposed within six feet of one — another ee showed large differences, which ere discussed in Section 6.2. ; 1. 3.i Other Factors The effact of elevation of gummed papers some three feat above the ground is unimow, as are the effects of tempera- . ture, dust, humidity and water on the adhesive properties of the gummed papers. These factors may be significant but cannot be evaluated here.