TLV's for Static Magnetic Fields

[Tad_Blanchard@ccmail.gsfc.nasa.gov]

Is this the correct interpretation of the ACGIH Threshold Limit Values 
for Static Magnetic Fields?  (I have a 1994 edition of the TWA booklet 
that listed this information as "Proposed Changes".)  
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Persons who wear pacemakers or other medical devices 
(Includes medical implants such as sutures, clamps, etc)  =  5 Gauss (G)

Ceiling value for workers (ceiling value)*                =  20,000 G

Time Weighted Average       Whole Body         Extremities

8-Hour TWA                      600 G            6,000 G 4-Hour TWA      
              1,200 G           12,000 G 2-Hour TWA                    
2,400 G           20,000 G* 1-Hour TWA                    4,800 G        
   20,000 G* 15-Minute TWA                19,200 G           20,000 G*


We are evaluating the construction of a building which will be used by 
researchers who will be using superconducting magnets.  We want to be 
sure that adequate warning is provided to pacemaker/implant wearers that 
magnetic fields are being produced.


************************* /^\   /^\ ***************************** 
Tad Blanchard            /___\ /___\  NASA-Goddard Space Flt Ctr  
Nat'l Health Svc, Inc         O       Greenbelt, Maryland        
Sr Health Physics Tech       / \      Phone: 301-286-9157         
                            /___\                                 
              Tad_Blanchard@ccmail.GSFC.NASA.gov                   
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