Lesson 3 – Occupational Health Programme For Noise

NOISE ASSESSMENT AND CONTROL

It is essential that a system be developed on every level of management to ensure the following:

 

Risk assessment /Hazard analysis

• A base line noise survey was conducted to identify all sources of noise on the mine.
• Sound pressure level surveys will be conducted continuously on the occupation hygienist routine visits to the working places determining noise zones and identify all employees working inside noise zones.
• All new installations and equipment will be measured and it will be the responsibility of the mine engineer to notify the occupation hygienist of any change in the plant or new equipment in use to conduct noise surveys.
• Continuous assessment of sound pressure levels of equipment will be conducted during routine visits at all working places.

     

Continuous Occupational Hygiene Monitoring.

• Personal noise measuring will be conducted with dosimeters to determine the exposure levels as per guideline. (See monitoring programme.)

 

The employer, in consultation with the Health and Safety Committee, shall determine all measures that are reasonably practicable, including changing the organisation of work and the design of safe systems of work, to:

• Eliminate any recorded risk;
• Control the risk at source; or
• Minimise the risk by implementation of effective engineering procedures
• Providing personal protective equipment as a last resort.
• Identification of all exposed employees.
• Personal protection equipment management programme.
• Medical surveillance of all employees exposed to noise in the workplace.
• Management of abnormalities and adverse trends.
• Training of all exposed employees.
• Awareness training to Contractors and other visitors that may be exposed.
• Analysis of all incidents.

It will be the duty of the occupational medical nurse to notify the occupation hygienist of any shift during the surveillance routine.

 

 

Occupation Hygiene Programme.

A formal hazard identification and hazard analysis must be performed in order to determine the areas where noise monitoring must be performed.  The employer has to identify all possible hazards to which employees are/may be exposed to in the workplace and, when exposure to noise is identified as a hazard, the employer must obtain the services of a suitably qualified Occupational Hygienist to determine personal noise levels.

 

Noise Measuring

• Measurements of noise levels are to be done by a person qualified in Occupational Hygiene techniques as prescribed by the MHSA.
• Noise measurements are to be conducted in accordance to SANS 083.
• Type two(2) noise dosimeters are used with criteria levels set at:

–Exposure limit 85dB

–Low threshold limit 80 dB

–Energy exchange (doubling rate) 3dB

• Areas identified as noise zones (8h-TWA equal or exceeding 85 dBA) must be zoned as noise zones. Zoning of noise areas has to be undertaken in terms of SANS Code 083. No employer may employ any person in an area where such a worker is exposed to a time weighted (8 hours) average noise level equal or exceeding 85 dBA (8h-TWA) unless certain prescribed actions are taken (8 hour shift for 5 days a week);
• Calibration of instruments used is to be done regularly and according to SANS 083 (2000).
• All certificates of calibration are to be kept for three years and must always be available for inspection by an inspector.
• Noise Control engineering (NCE)

A plan of action must be compiled in the Hearing Conservation Programme to manage the risk of employees being exposed.  Supervisors must attempt to eliminate exposure to noise levels equal to or in excess of 85dBA by engineering techniques.  Where it is impossible to eliminate exposure, steps must still be taken to minimise the exposure.  To this end a task team must be established to investigate the possibility of corrective action to mitigate or eliminate noise.  This task team will be responsible to draw up a mine procedure.  (Hearing Conservation programme)(HCP)

These recommendations as well as the corrective actions taken must be documented, kept on record for three years and must be available for inspection.

In areas where noise levels cannot be reduced to below 85dBA, these areas must be demarcated as noise areas and a medium and long term action plan should form part of the Hearing Conservation Programme.  The programme will include the Milestone of reducing all noise sources to below 110dBA at source.  Targets must be set to reduce personal exposure to below 110dBA at the year 2008 and below 105dBA at 2013.  Zoning is the marking of the whole area with appropriate symbolic signs at all entrances to that area that indicate that wearing of hearing protectors is compulsory.  In outdoor areas where noise zoning is not fixed and cannot be demarcated by means of a line or similar means, a strict training programme must be implemented to ensure that persons are aware when entering a noise zone to prevent any possible disputes.

 

Intervals of noise measuring:

• Noise measurements at source and assessing zoning of all relevant areas have to be done at least every two years as a routine action.
• Any change in the workplace, or the working processes, which may alter the existing sound levels to which employees are exposed to has to be re-evaluated by a person certified to do noise measurements and zoning.

 

Identification of exposed employees

• After measuring and zoning of workplaces the Occupational Hygienist determine the Homogeneous Exposure Groups.

 

The Occupational Hygienist is responsible to identify all employees who are exposed to noise and to categorise employees into one of the following categories:

• Employees exposed to more than 82 dBA.
• Employees exposed to noise levels equal or in excess 85 dBA.
• Employees exposed to noise levels equal or in excess to 105 dBA.
• Employees exposed to impulse noise.
• It is the responsibility of line management in co-operation with the Occupational Hygienist to update workstations where employees are exposed and to ensure that all relevant information is passed onto the Occupational Medical Practitioner for entering relevant information into medical files of employees.

 

Noise Sources identified during the baseline risk assessment.

Underground

• Rock drills, Loaders, Auxiliary Fans, Main fans, Compressed air, Winches and scrapers, falling rock (loading in hoppers),Locos, diesel powered machinery.
• Activities: Drilling, blowing out holes, scraping, lashing, loading, grinding, hammering, blasting, sample cutting.

 

Surface.

• Crushing, screening, falling rock (transfer chutes), Milling, Electrical motors, Blowers, Compressors, Mobile machinery, Hand held tools,
• Activities. : Hammering, grinding, Loading,

 

DETERMINATION OF H.E.G.’s

• The labour force are divided into homogeneous groups according to their exposures identified in the risk assessment and results of measurements made in the past.

 

Step 1. Description of Sampling Areas.

• The mine is divided into three Sections and each section is divided into 2 sampling areas Sampling Area 1 is Underground Operations and Sampling Area 2 is Surface operations. Sampling Area 3 is added to Fairview surface Tailings Re-mining process.

 

Step 2. Description of activity areas:

• Employees who are working in the same working environment with more or less the same exposure levels have been grouped into the same activity areas. Personal measurements can be used to determine the range of all employees working in the same activity area.

 

Step 3. Evaluate the Risk Assessment

• Results of personal noise readings during the risk assessment process have been used to determine occupational exposure within the activity area.

 

Step 4. Compare Noise Results.

• Results of noise measurements in an activity area and the employee’s relation to the source of the noise levels were compared to determine homogeneous exposure. Eg. Time of exposure, distance from the source and the sound level of the source.

 

Step 5. Categorise each activity area into classification bands.

• The table below was used to classify the activity areas.

 

PERSONAL NOISE EXPOSURE MONITORING.

• Personal exposure monitoring consists of accurate, meaningful samples, which are representative of all full working shifts;
• Individual exposure records are compiled annually based on the annual report for that year;
• The number of samples to be taken is based on the prevailing category band. Additional sampling will be conducted on employees indicating hearing loss on their audiometric testing in any category when reported by the medical department.

 

OCCUPATIONAL MEDICAL SURVEILLANCE – including 8.3

• All employees working, or entering into, an area where the noise level (8h-TWA) is equal to or exceeding 85 Laeq(8) dBA should be subdued to a medical surveillance program according to the medical surveillance guideline.
• Employees with existing hearing impairment, or any other disease, which render such an employee more sensitive to develop hearing impairment from exposure to noise at his/her workplace, are to be subdued to a more intensive monitoring programme. This monitoring programme is to be developed by the Occupational Medical Practitioner appointed for the mine.
• Results of employees who are identified with NIHL must be reported to the Occupation Hygienist for investigation.

 

Pre audiogram medical examination

• Prior to the commencement of any audiometric testing the employee will undergo an otoscopic examination by the Occupational Health Practitioner to ascertain the presence of wax or adverse pathology in the ear canal that could adversely influence the hearing thresholds.
• Should wax be found in the ear canal, the employee must be referred for the obstruction to be removed and the patient allowed recuperating for several days before re-testing commences.
• Employees found to be suffering from infection; discharge or similar problems will be sent for medical advice and treatment and re-scheduled for testing after the ailment has cleared.
• An assessment of the ear canal to establish compatibility for hearing protector devices must be carried out.

 

The Hearing Surveillance Programme shall include the following types of audiometric testing:

 

Baseline audiogram

a.New employees with no previous medical records.

• An audiogram obtained from audiometric examination performed prior to employment or within 30 days of employment. It is performed after a period of at least 16 hours has elapsed since the employee was last exposed to noise. The use of hearing protection devices to effect this attenuation will not be acceptable [Mine Health and Safety Act].  All subsequent audiograms will be compared to this to determine deterioration in percentage hearing loss (PHL).
• The baseline audiogram must be done as prescribed in the guideline and the audiometrist must ensure that the difference between the two tests does not exceed more than ³ 10 dB for any of the measured test frequencies.

 

b.New employees with previous mine experience.

• All new employees must provide the Occupational Health department with the Exit Medical report from the previous employer. The Occupational Health Practitioner (OHM) must request a copy of the Baseline audiogram from the previous employer.

 

Periodic audiometry

• An audiogram that is obtained as part of on-going medical surveillance. All exposed employees working in noise zones shall undergo audiometric testing according to the Medical Surveillance Program.

 

Frequency of periodic audiogram

• The employer must ensure that a periodic audiogram is obtained at least annually for all employees subject to medical surveillance (i.e. workers exposed to an equivalent noise level (Laeq(8)) exceeding 85 dB.)
• Screening audiometry is performed after a period of at least 16 hours has elapsed since the employee was last exposed to noise. Appropriate hearing protection devices may not be used to fulfil the 16-hour noise free requirement.
• Record exposure prior to examination with each audiogram.
• Objectives: Monitor auditory status of the individual;
• Early identification of auditory damage. (Monitoring variances)

 

Monitoring audiometry

• Employees exposed to noise levels greater than 100 dBA shall undergo random audiometric monitoring/testing. Audiometric monitoring shall be recorded before the work shift commence and within 2hrs post work shift to determine temporary threshold shifts to monitor the effectiveness of the hearing conservation programme.

 

Exit audiogram

• All employees subject to medical surveillance must have an Exit audiogram when terminating their service on this mine. An audiogram conducted within the preceding 6 months may be used as an exit audiogram (presuming that no event has occurred subsequent to this test that may have affected hearing). The exit audiometry must be done within fourteen (14) days after termination of service.

 

REPORTING OF NIHL CASES.

Internal reporting

• Any employee who suffers from noise induced hearing impairment with a PLH shift equal to or more than 2% from the previous year:

–The Occupational Health Practitioner must report all these cases to the Manager for counselling, re-training and compliance monitoring of PPE application.

–The direct line supervisor must also be informed of these cases.

–Re-training of such an employee must be done and all training must be recorded in the incumbent’s personal file.

–Incident analysis must be performed.

–An HPD compatible assessment must be done to ensure that the HPDs issued provide sufficient protection.

 

 

Reporting to DMR

• Any employee who suffers from noise induced hearing impairment with a PLH shift equal to or more than 5% but less than 10%from the base line:

–The Occupational Health Practitioner must submit the report on serious illness or health threatening occurrence.

–The Occupational Health Practitioner must notify the Occupational Hygienist to an incident investigation and analysis.

–The incident must be investigated and the report must be submitted within 30 days to the regional principal inspector.

 

 

HANDLING OF EMPLOYEES WHO ARE COMPENSABLE

Definition:

• “Reportable” is defined as employees qualifying for compensation as prescribed by Internal Instruction 171 (Compensation Commissioner).

 

Steps to be followed:

• A qualified audiometrist should conduct a valid screening audiogram (minimum 16 hrs noise free) (where the PLH is more or equal to 30% the opinion of an ENT specialist is required.)
• The employee should then be referred to a registered Audiologist for diagnostic audiometry (minimum 24hrs noise free)
• If it is confirmed by the Audiologist that the impairment can be the result of exposure to noise, the case should be communicated to the Compensation Commissioner as well as to the Department of Minerals and Energy-Chief Inspector.