Re: Day/Night background change

[john.r.johnson@ccmail.pnl.gov (John R Johnson)]

     Most operators of WBC are aware that radon progeny will attach to 
     synthetic fiber materials, and usually recommend that cotton 'white' 
     be worn to reduce the false positives.
     
     Also, ground level radon concentrations increase at night when natural 
     vertical mixing due to insolation is reduced. Any of the relevant 
     UNSCEAR reports can be refered to for more details.
     
        John R Johnson, PhD
        Scientist Emeritus, HPD/PNNL
        MS K3 53
        Box 999
        Richland, WA, 99352
        e:mail; jr_johnson@pnl.gov
        Phone: (509) 375-6850 
        FAX:   (509) 375-2019