Inter-laboratory comparisons of measuring instruments of microwave radiation in the workplace / 中国职业医学

ABSTRACT

OBJECTIVE: To evaluate the feasibility of the inter-laboratory comparison of microwave radiation measuring instruments which uses cellphone signal shielding device as standard source,and to establish inter-laboratory comparison method of microwave radiation.METHODS: The typical sampling method has been used by selecting twenty-one measuring instruments of microwave radiation from 21 occupational hygiene technical service organizations as study subjects.A cellphone signal shielding device was applied as standard source.Measurement points were measured by surveyors at a distance of 1.0 and 1.5 meter to the standard source,and the measurement results were analyzed by four robust technology and z-score evaluation method.RESULTS: Stability test showed that there was no statistical difference among the power density of standard source which were measurement at three diffluent time [(26.10 ± 0.94) vs(25.78 ± 0.27) vs(25.83 ±0.47) μW/cm~2,P>0.05].The standard source stability can also satisfy the requirement of inter-laboratory comparison.Among the 21 selected equipments,one of the 21 measuring instruments was not calibrated,one calibration certificate of the instruments was expired,and one calibration result of the instruments was unqualified.The z score of inter-laboratory(z_B) of 21 measuring instruments ranged from-1.27 to 4.85,while z score of within-laboratory(z_w) ranged from-1.42 to 2.18.One | z_B| of the instruments was above 3.00,while | z_W| was above 2.00.Comprehensive evaluation of the above results showed that only one instrument was unqualified.CONCLUSION: It is feasible that a cellphone signal shielding device could be applied as standard source.The method developed in this study can be used to understand the performance of microwave radiation instruments.