Code of Massachusetts Regulations
105 CMR - DEPARTMENT OF PUBLIC HEALTH
Title 105 CMR 122.000 - Nonionizing Radiation Limits For: The General Public From Non-occupational Exposure To Electromagnetic Fields, Employees From Occupational Exposure To Electro-magnetic Fields, And Exposure From Microwave Ovens
Section 122.290 - Appendix A: Measurement Procedure for Radiofrequency Exposure

(a) These measurements are to be made utilizing the methods described in the National Council on Radiation Protection and Measurements (NCRP) Report No. 119 A Practical Guide to the Determination of Human Exposure to Radiofrequency Fields or by other methods acceptable to the Director.

(b) The applicable power density, mean squared electric or magnetic field strengths, should be determined for public exposure pursuant to 105 CMR 122.015(A), as the average value over any 0.5 hour period. Should operation(s) be less than for 0.5 hour periods the following formula should be used:

P = K/T where:

P is the allowable maximum level;

K is the maximum exposure level stated in 105 CMR 122.015 Table 1; and,

T is the ratio of the exposure duration in a 0.5 hour to one half hour.

(c) In the far field region, compliance with 105 CMR 122.015 may be determined using a field strength measuring instrument which is d e signed and calibrated to give a direct reading of the equivalent plane wave free-space power density. Such direct measurement of the equivalent plane wave free-space density measurement of the equivalent plane wave free-space density cannot be accurately carried out in the non-far field region. To determine compliance with 105 CMR 122.015 in the non-far field region, the mean squared electric field strength and the mean squared magnetic field strength should be measured separately. Dipoles and spectrum analyzers should be used in multiple frequency environments. These values may then be used to calculate the equivalent plane wave free-space power density.

(d) The effects of contributing sources of frequencies below and above frequency limits of broadband instruments may be included by appropriate separate single instant measurements of the contribution due to these sources. Further, levels below 20 microwatts / cm2 or the lowest detectable level, whichever is lesser, should be deemed zero for further computational purposes.