Encyclopedia of Environmental Science and Engineering, Volume I and II

788 NON-IONIZING RADIATIONS

APPENDIX B

that they can adequately withstand power densities of at least

10 mW/cm^2 without interference with their function.”

PREFERRED READING

1. Clarke, A.M. (1970), “Ocular Hazards from Lazers and other Optical
   Sources,” CRC Critical Reviews in Environmental Control, 1 , 307.


2. Cleary, S.F. (1970), “The Biological Effects of Microwave and Radio-
   frequency,” CRC Critical Reviews in Environmental Control, 1 , 257.

REFERENCES

1. Matelsky, I., The non-ionizing radiations, Industrial Hygiene High-
   lights 1 , Indus, Hygiene Foundation of America Inc. Pittsburgh, Pa.,
   1968.


2. Ibid. p. 145.


3. Ibid. p. 149.


4. Cogan, D.G. and V.E. Kinsey (1946), Action spectrum of keratitis pro-
   duced by ultraviolet radiation, Arch. Ophthal. , 35 , 670.


5. Verhoeffr, F.H. and L. Bell (1916), Pathological Effects of Radiant
   Energy on the Eye, Proc. Amer. Acad. Arts and Sci. , 51 , 630.


6. Pitts, D.G., J.E. Prince, W.I. Butcher, K.R. Kay, R.W. Bowman, H.W.
   Casey, D.G. Richey, L.H. Mori, J.E. Strong, and T.J. Tredici, The
   effects of ultraviolet radiation on the eye, Report SAM-TR -69-10, USAF
   School of Aerospace Medicine, Brooks AFB, Texas, Feb., 1969.


7. Pitts, D.G. and K.R. Kay (1969), The photophthalmic threshold for the
   rabbit, Amer. J. Optom. , 46 , 561.


8. Permissible limit for continuous ultraviolet exposure, Council on Physical
   Therapy, Amer. Med. Assn., Chicago, 1948.

Conversion factors Aradiant energy units

erg joule W/sec W/sec g-cal

erg  110 ^710 ^7 0.1 2.39  10 ^8

10 joule  11106 0.239

W sec  107 1 1 104 0.239

W sec  10 10 ^610 ^61 2.39  10 ^7

g-cal  4.19  107 4.19 4.19 4.19  106 1

Bradiant exposure (dose) units

erg/cm^2 joule/cm^2 W/sec cm^2 W/sec cm^2 g-cal/cm^2

erg cm^2  10 ^710 ^7 0.1 2.39  10 ^8

joule cm^2  107 11106 0.239

W sec cm^2  107 11106 0.239

W sec cm^2  10 10 ^610 ^6 2.39  10 ^7

gcal cm^2  4.19  107 4.19 4.19 4.19  106 1

C-irradiance (dose rate) units

erg/cm^2 · sec joule/cm^2 · sec W/cm^2 W/cm^2 gcal/cm^2 · sec

erg/cm^2 · sec  110 ^710 ^7 0.1 2.39  10 ^6

joule cm^2 · sec  107 11106 0.239

W/cm^2  107 11106 0.239

W/cm^2  10 10 ^610 ^61 2.39  10 ^7

g-cal/cm^2 · sec  4.19  107 4.19 4.19 4.19  106 1

A tabular summary of typical characteristics of instru-

mentation used for electromagnetic fi eld measurements is

available in an NCRP report.

Control Measures

The control of excessive exposures to microwave radiation is

basically an engineering matter. The engineering measures

may range from the restriction of azimuth and elevation

settings on radar antennas to complete enclosures of mag-

netrons in microwave ovens. The use of personnel protec-

tive devices have their place but are of much lower priority

importance to engineering controls. Various types of micro-

wave protective suits, goggles and mesh have been used for

special problems.

It has been shown that cardiac pacemakers, particularly

those of the demand type, may have their function compro-

mised by microwave radiation. Furthermore, the radiation

levels which cause interference with the pacemaker may be

orders of magnitude below levels which cause detrimental bio-

logical effects. The most effective method of reducing the sus-

ceptibility of these devices to microwave interference seems

to be improved shielding. Manufacturers of cardiac pacemak-

ers “... have successfully redesigned and shielded the units so

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