Wei Gong / Jiangsu Provincial CDC, China Yufei Liu / 3M China Xin Liu/ Jiangsu Provincial CDC, China NHCA Conference Feb. 2017, Texas Field surveys of earplugs fit- testing in China
Disclaimers The findings and conclusions in this presentation have not been formally disseminated by Jiangsu Provincial Center for Disease Control and Prevention, and should not be construed to represent any agency determination or policy. Mention of a company or product does not constitute endorsement by Jiangsu Provincial Center for Disease Control and Prevention.
3M E-A-Rfit Dual- Ear Validation System NIOSH HPD Well-Fit Personal Attenuation Rating (PAR) Noise attenuation headphones Laptop USB mouse
Test procedure Questionnaire Baseline / initial PAR failed No Noise Measure Completed Train & refit (intervention group) PAR failed again No New HPD & refit Yes
Part 1, Primary results with E-A-Rfit
Part 1, E-A-Rfit Information about surveyed factories Foam earplug Premolded earplug Model 3MT M 1110/1100 3M TM 1270 Labeled attenuation Factories and PAR criteria Relative ranking of HCP quality NRR: 29 db SNR: 37 db A: Machinery (15 db) B: Machinery (15 db) C: Textile (18 db) D: Power plant (10 db) A: No. 1, good follow-up action B: No. 2, average C: No. 3, poor HPD enforcement D: No.4, not good HPD enforcement NRR: 24 db SNR: 25 db E: Petrochemical (15 db) including 5 workshops E: No. 2, average
Part 1, E-A-Rfit General information about test subjects Service year Years of use of HPD Noise exposure duration per working day in hours <1 year 1 to 5 years 6 to 10 years >10 years 10 (10%) 281 (32%) 95 (11%) 504 (57%) <1 year 1 to 2 years 3 to 6 years >6 years 63 (9%) 116 (16%) 220 (30%) 328 (45%) < 1 h 1 to 4 hrs 5 to 8 hrs > 8 hrs 1 (0%) 224 (25%) 446 (50%) 214 (24%) Education level Grade school Junior high school High school Junior college or above 37 (4%) 170 (19%) 260 (29%) 432 (48%) Gender Male Female 723 (82%) 159 (18%)
Part 1, E-A-Rfit PARs - baseline vs. labeled attenuation value 35 Foam earplug n Mean (db) SD (db) 27 22 23 PAR - baseline 375 11 9.0 Premolded earplug n Mean (db) SD (db) PAR - baseline 685 10 7.6 11 10 Foam Premolded PAR - baseline 2-dB corrected NRR 2-dB corrected SNR
Part 1, E-A-Rfit Effect of one-on-one training 35 Foam earplug Premolded earplug n PAR - Baseline PAR - after training Mean SD Mean SD (db) (db) (db) (db) 273 8 8.3 21 3.9 451 6 6 18 3.4 21 27 18 22 23 8 6 Foam Premolded PAR - Baseline 2-dB corrected NRR PAR - after training 2-dB corrected SNR
PAR (db) Part 1, E-A-Rfit Effect of hearing conservation practice NOTE: Relative ranking of HCP quality is factory A > B > C 35 30 PARs at baseline and after training, for initial visit, foam-earplug intervention group Factory A Factory B Factory C 25 20 15 10 5 0 n=56 n=49 n=144 Baseline After training
PAR (db) Part 1, E-A-Rfit Effect of hearing conservation practice NOTE: Relative ranking of HCP quality is factory A > B > C 40 35 30 Follow-up visit for foam-earplug intervention group (n=97) Factory A Factory B Factory C 25 20 15 10 5 0 n=29 n=22 n=46 Baseline After training - 1st visit Follow up visit
Part 1, E-A-Rfit Easier to fit = easier to obtain higher protection? n Mean (db) SD (db) Premolded earplug initial in follow-up visit Foam earplug initial in follow-up visit 18 13.5 8.6 18 18.1 8.6 P-Value = 0.1
PAR (db) Part 1, E-A-Rfit Easier to fit = easier to sustain the training effectiveness? 30 Follow-up visit for premolded earplug intervention group (n=74) 25 20 15 10 5 0 Subjects Baseline After training Initial at 6-month follow up
Part 1, E-A-Rfit Is training conducted on representative group enough? n Mean (db) SD (db) P-value Baseline PAR Apr. 2016 Baseline PAR Sep. 2016 215 10.2 7.5 0.08 83 11.8 7.3 NOTE: Baseline PARs measured in Apr. and Sep. were from the same workshop.
Part 2, Primary results with Well-fit
Noise exposure levels (dba) Part 2, Well-Fit Information about surveyed factories Honeywell Bilsom 304S 3M TM 1270 3M TM 1270 3M Yellow Neons HCP=3 No annual audiometry HCP=3 No annual audiometry 3M TM 1100 HCP=3 No annual audiometry n=55 HCP=4 Annual audiometry Factory F Factory G Factory H Factory I Factories
Part 2, Well-Fit Demographics of workers Factory F Factory G Factory H Factory I Age Number Number Number Number <31 10 16 22 36 31-40 13 7 4 3 41-50 5 2 0 5 >50 0 0 0 8 Gender male 24 21 26 52 female 4 4 0 3 Total 28 25 26 52
PAR (db) Part 2, Well-Fit Effect of fit-testing PARs of baseline and after intervention on earplugs 40 Initial Fit-Test Final Fit-test 30 20 10 0 Factory F, n=28 Factory G, n=25 Factory H, n=25 Factory I, n=55
Part 2, Well-Fit Effect of intervention Recommed Muff, 3% HPDs changed, 20% Passed first time, 69% Passed after intervention, 29% Training, 80%
Part 2, Well-Fit Do education levels play roles on PAR?
Part 2, Well-Fit Hearing thresholds (db) Well-fit = hearing screening tool? 100 Hearing threshold of subjects groups with and without hearing loss from audiometry 80 60 40 20 0 500 1000 2000 4000 500 1000 2000 4000 Left ear Frequency (Hz) Right ear group with hearing loss group without hearing loss
Part 2, Well-Fit Hearing thresholds (db) Well-fit = hearing screening tool? 100 Hearing threshold of subjects groups with/without hearing loss from Well-Fit 80 60 40 20 0 500 1000 2000 4000 500 1000 2000 4000 Occluded group with hearing loss Frequency (Hz) group without hearing loss Unoccluded
Absolute hearing thresholds (db Part 2, Well-Fit Interesting case- a worker with cotton ball 100 80 Occluded with cotton ball Occulded with 3m 1100 Unoccluded 60 40 20 500 1000 2000 4000 Frequency (Hz) Quote from Karplus Bonvallet - A Noise Survey of Manufacturing Industries
Absolute hearing thresholds (db) Part 2, Well-Fit Best results of hearing protection practice 80 70 60 Task worker 1 worker 2 Prefabrication Operator 50 40 30 20 10 0 Left Ear Frequency (Hz) Right Ear 500 1000 2000 3000 4000 6000 500 1000 2000 3000 4000 6000 Worker 2 20 31 58 53 54 72 20 26 48 48 49 72 Worker 1 20 20 20 38 29 22 20 20 20 33 34 12 Age 58 57 work years 39 40 HPD used Cotton ball 3M TM 1100 Years of use of HPD 39 8
Conclusion Hearing protectors, even cotton balls are better than nothing; Individual fit-testing is the only way to definitely know whether a worker is adequately protected from noise; Individual training and intervention is necessary for workers exposures to high noise regardless of education levels; Follow-up testing is needed to figure out what is best period for redo the fit-testing; HPDs Well-fit could potentially be a hearing screening tool in the future.
Tips on field survey of HPDs fit-testing system Conduct noise measurement prior to field fit-testing; To reduce the test time, it is better to input the information of workers tested prior to field fit-testing; Well-Fit needs a quite test environment, such as a conference room or office; An ideal test team consists of 3-4 persons - one for questionnaires, at least one for fit-testing, and one for training failed workers, operating in different rooms to avoid creating background noise. Detailed feedback to HES managers is very important.
Acknowledgements NHCA William Murphy, PhD, NIOSH Elliott H. Berger, MS, 3M Xin Liu, PhD, JSCDC, China
Reference ANSI (1974). "Method for the Measurement of Real-Ear Protection of Hearing Protectors and Physical Attenuation of Earmuffs," Am. Natl. Stds. Inst., S3.19-1974, New York, NY. Gauger D, Berger EH (2004). A new hearing protector rating: the noise reduction statistic for use with A weighting (NRSA). Report for US Environmental Protection Agency. Approved by ANSI S12/WG11, E-A-R 04-01/HP, Indianapolis, IN. Karplus Bonvallet - A Noise Survey of Manufacturing Industries - Ind. Hyg. Quart. 235-263,1958 William J, Christa L. Themann, Taichi K. Murata. Field-Testing NIOSH HPD Well-Fit: Off-Shore Oil Rig Inspectors in Texas & Louisiana. EPHB Report No. 360-11a