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.

OBJECTIVE: To analyze the influence of noise measuring skills by continuous inter-laboratory comparison among occupational hygiene technical service organizations. METHODS: The results of 68, 55 and 50 occupational hygiene technical service organizations(reference organizations) participating in the inter-laboratory comparison of workplace noise measurement in 2014, 2017 and 2018 respectively were collected. The measurement operation and the calculation of equivalent sound level were evaluated according to the GBZ/T 189.8-2007 Measurement of Physical Agents in Workplace--Part 8: Noise.The measured results were analyzed by z score evaluation method. RESULTS: The results of noise measurement field operation of the reference organizations in the year 2014, 2017 and 2018 show that the accuracy rates of instrument setting was 89.7%, 98.2% and 100.0%, the accuracy rates of measuring position were 52.9%, 81.8% and 94.0%, the accuracy rates of sound level meter holding were 54.4%, 80.0% and 92.0%, the accuracy rates of microphone pointing were 98.5%, 98.2% and 94.0%, and the accuracy rates of noise type recognition were 83.8%, 92.7% and 84.0%, respectively. Among them, the accuracy of instrument setting, measurement position and sound level meter holding showed an increasing trend year by year(P<0.01). The pass rates of measurement results were 91.2%, 94.5% and 88.0% in 2014, 2017 and 2018 respectively. The pass rates of equivalent sound level calculation were 73.5%, 92.7% and 88.0%. The pass rates of comprehensive evaluation were 70.6%, 89.1% and 80.0% respectively. Among them, the pass rates of equivalent sound level calculation and comprehensive evaluation in 2017 were higher than that in 2014(P<0.017). There was no significant difference in the three-year comprehensive assessment total pass rate between private organizations and non-private organizations(84.0 % vs 75.5%, P>0.05). There was no significant difference in the total pass rate of three-year comprehensive evaluation between non-Pearl-River-Delta organizations and Pearl-River-Delta organizations(70.3% vs 81.6%, P>0.05). CONCLUSION: Continuous inter-laboratory comparison in occupational hygiene technical service organizations is beneficial to improve on-site noise measure capability.