Mine Health and Safety Council STS PRINCIPLES & IMPLEMENTATION REQUIREMENTS Dr Dipalesa Mokoboto
OUTLINE • WHAT IS STANDARD THRESHOLD SHIFT(STS) • HX- SANS 10083- PERIODIC SCREENING • BACKGROUND • OBJECTIVES • IMPORTANT DEFINITIONS • ILLUSTRATION OF DEFINITIONS • MILESTONE BASELINE(MB) PRINCIPLES • MONITORING FOR STS • IMPLEMENTATION
DID YOU KNOW
A Standard Threshold Shift , or STS, is defined in the occupational noise exposure standard as a change in hearing threshold , relative to the baseline audiogram for that employee, of an average of 10 decibels (dB) or more at 2000, 3000, and 4000 hertz (Hz) in one or both ears.
ASSESSMENT OF PERIODIC AUDIOGRAMS SANS 10083- 2013 • Periodic screening audiograms assessed for their absolute values and compared with baseline • The PLH-shift: • Shifts of 3.2% < 6.4% = Intervention • Shift of 6.4% < 10% = Advanced Intervention • Shift of 10 % from the baseline results trigger specified action
ASSESSMENT OF PERIODIC AUDIOGRAMS MHS REGULATIONS only Intervention at PLH shifts of > = 5% 1. Same as Intervention SANS (as loss> 3.2%) 1. Employer to investigate & determine cause 2. Inspect & check PPE for adequacy 3. Inspect fit & use of PPE by employee 4. Retrain employee in Regulation 3 5. Document intervention & archive for 40 years 2. Reporting 1. Complete Health Incident reporting form
ASSESSMENT OF PERIODIC AUDIOGRAMS Intervention at PLH shifts of > 6.4% < 10% 1. Employer to investigate & determine cause- must include re-test and otoscopy 2. Diagnostic test by audiologist to be considered 3. Inspect & check PPE for adequacy 4. Inspect fit & use of PPE by employee 5. Retrain employee in Regulation 3 6. Document intervention & archive for 40 years
BACKGROUND SUMMIT MILESTONE 2014: by December 2024, no employees’ STS will exceed 25db from baseline when averaged at 2,3 and 4 KHz in one or both ears. – The Guidance Note on the Implementation of the Standard Threshold Shift has been developed – Provides framework to manage the risk of noise exposure proactively. – Mining Occupational Health Advisory Committee (MOHAC) established a Task Team. – Facilitated development of STS Guidance Note in line with Summit Milestone 2014. – STS Guidance Note designed around best practice principles and standards
OBJECTIVES • Provide framework to assist the employers to implement the Standard Threshold Shift (STS) principles • Give opportunity for employers to educate employees about their hearing and the need to preserve and protect it • Monitor with the intent to prevent noise induced hearing loss in line with the 2014 Milestones BUT – STS principles do not apply to compensation for NIHL and – Will not replace instruction 171 in terms of COIDA
IMPORTANT DEFINITIONS • Milestone baseline as determined will mean audiometric Zero • Standard Threshold Shift (STS) - average change in hearing of 10dB or more at the frequencies of 2000Hz, 3000Hz and 4000 Hz in one or both ears as compared to the employee’s milestone baseline audiogram. • Reportable level- if the average change in hearing from milestone baseline STS, is 25dB hearing loss or greater at the same frequencies in the same ear.
Hearing + Frequencie • Hair cells in the cochlea are tuned to specific frequencies • Base of the cochlea is sensitive to high frequency sounds (red dots) • Tip of the cochlea is sensitive to low frequency sounds (green dots)
Loud Noise Levels Loud noise Damaged cochlea High noise levels damage the first turn of the cochlea – where high frequency sounds are heard
ILLUSTRATION OF DEFINITIONS
Calculation-Example Two 2000 Hz 3000 Hz 4000 Hz 2004 Baseline 20 25 30 Audiogram dB 2005 Annual 25 25 40 Audiogram dB Shift in hearing dB 5 0 10 The baseline audiogram shows a person with an existing mild hearing loss. The annual audiogram shows a change in hearing ability, but not enough to be a Standard Threshold Shift. (5+0+10)/3 = 15/3 = 5 Although the hearing change is not enough to have a Standard Threshold Shift, there has been a 10 dB change at 4000 Hz, the most likely frequency to be damaged by workplace noise. It would be a good idea for the employer to re-evaluate the noise protection program for this employee to prevent further hearing loss.
Screen shot example
MILESTONE BASELINE PRINCIPLES • MB audiogram conducted on every current employee in any working place where the equivalent continuous A-weighted sound pressure level, normalised to an eight hour day or a forty hour working week, is equal to or exceeds 85 decibels A dB(A) • From 1 July 2016 a milestone baseline audiogram must be conducted within 30 days of commencement of employment on every new employee exposed to any working place where the equivalent continuous A-weighted sound pressure level, normalised to an eight hour day or a forty hour working week, is equal to or exceeds 85 decibels dB(A).
MILESTONE BASELINE PRINCIPLES • MB only conducted if the employee removed 16 hours from noise >85 dB(A). • MB audiogram is the better of the employee's two audiograms performed by an audiometrist on the same day and do not differ from each other by more than 10 dB • If can’t obtain two audiograms that conform to requirements above, refer to an audiologist to establish the MB. • Audiologist may determine the MB by other techniques .
MILESTONE BASELINE PRINCIPLES • All subsequent audiograms conducted during medical surveillance examinations will be compared to the MB audiogram to determine if STS has occurred and if the STS is reportable, or not. • An employee’s MB must be recorded and kept for 40 years with the medical surveillance records. • When a reportable level is reached, the audiogram conducted at that time becomes the new MB for the purposes of future monitoring
MONITORING FOR STS • Determine if the employee’s results indicate an STS • Determine if STS is reportable or not (Aver 25db change in hearing from MB) • If STS is reportable then: 1. Inform the employee of the STS and the implications 2. Counsel employee on danger of exposure to noise 3. Advise employer - appropriate management measures to prevent permanent hearing loss to employee at risk.
IMPLEMENTATION • MB to be completed by 31 December 2017 Allow 12 to 24 months to complete MB, (size of workforce at risk) Software programme changes to be completed sooner than later. MB audiogram must be conducted between 1 July 2016 and 31 December 2017 on every current employee(Noise =/>85db) From 1 July 2016 a MB audiogram must be conducted within 30 days of commencement of employment on every new employee exposed to noise=/>85db Monitoring for STS from MB will commence January 2018
CONCLUSION • Need for better early indicators of hearing loss • Early intervention to prevent more significant loss • STS implementation ensures risk of noise exposure is effectively managed and • Improved Occupational Health performance • STS principles aligned to international best practice and standards • Using STS is proactive and preventative. • Prevention is better than cure.
CONCLUSION
OUTLINE
CONCLUSIONS
CONCLUSION THANK YOU KEA LEBOHA
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