Outline some of the key health and safety challenges that is faced by a mining company you are familiar with. The industry has experienced both high consequence low frequency events (disasters such as Moura and Gretley) as well as low frequency high events (such as slips, strains and falls) contribute to the industry's high lost time injury rate (LTIR). It has also had its share of occupational diseases. Historically, pneumonocosis (lung disease caused by inhalation of mineral dust), asbestosis and mesothelioma have been key areas of concern. Noise, vibration and fatigue are issues of significant health concerns. The management and control of major hazards associated with structural collapses, fires and explosions are key safety issues of the day.
During the past forty years there have been three mining disasters in the Moura district at a cost of 36 lives.
The first occurred at Kianga Mine on 20 September 1975. Thirteen miners died from an explosion which was found to have been initiated by spontaneous combustion. The mine was sealed and the bodies of the men were never recovered.
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The second occurred on 16 July 1986 at Moura No 4 Mine when twelve miners died from an explosion thought to have been initiated by one of two possible sources, namely frictional ignition or a flame safety lamp. The bodies of the miners, in this case, were recovered.
The third of the disasters occurred on 7 August 1994 at Moura No 2 Mine. On this occasion eleven miners died as a result of an explosion. The mine was sealed and, at this time, the bodies have not been recovered.
What is the framework of the mine safety legislation in your state/country?
Since Australia is a federation of states, each state sets out its own laws, which include its own regulatory standards for occupational health and safety. At beginning, each state was separate and used the old health codes (i.e., legislation) and standards from the British system. This system relied heavily upon very specific (i.e., numbers based) system which was easy to enforce and simple to understand. However problems ensured as time and technology progressed which led to the health and safety reform that began in 1972.
The Current Framework for Mine Safety in Australia in 3 ways:
Regulations under a general OHS Act (VIC/SA/TAS/NT)
In separate Mine Safety Acts and Regulations (WA/QLD)
In separate mine Safety Act and Regulations Subordinate to a general OHS Act (NSW)
Since Victoria is my state, the following legalisation will be used under 3 main categories given as below.
Dangerous Goods Act
Environment Protection ACT
Occupational Health and Safety Regulations
As per Occupational Health and Safety Regulations:
Occupational Health and Safety Act 2004. Act No. 107/2004: Enabling act. Sets out the key principles, duties and rights in relation to occupational health and safety (OHS).
Occupational Health and Safety Regulations 2007,Statutory Rule No. 54/2007: Specifies the way in which a duty imposed by the OHS Act must be performed, or prescribe procedural or administrative matters to support the OHS Act (eg requiring licences for specific activities, the keeping of records or giving notice).
WorkSafe Positions: Are guidelines made under section 12 of the OHS Act that state how WorkSafe will apply the OHS Act or Regulations or exercise discretion under a provision of the OHS Act or Regulations. WorkSafe Positions are intended to provide certainty to duty holders and other affected parties
As per Environment Protection ACT:
Version No. 171, Environment Protection Act 1970, No. 8056 of 1970, Version incorporating amendments as at 1 January 2010.
This sets out the key principles, duties and rights in relation to Environment Protection Act.
As per Dangerous Goods Act:
This sets out the key principles, duties and rights in relation to Dangerous Goods Act. But here individually they all made for individual categories as mentioned.
Version No. 081
Dangerous Goods Act 1985
No. 10189 of 1985
Version incorporating amendments as at 1 January 2010
Version No. 003
Dangerous Goods (HCDG) Regulations 2005
S.R. No. 96/2005
Version as at 14 March 2008
Version No. 005
Dangerous Goods (Storage and Handling) Regulations 2000
S.R. No. 127/2000
Version incorporating amendments as at 1 January 2009
Always on Time
Marked to Standard
Version No. 001
Dangerous Goods (Transport by Road or Rail) Regulations 2008
S.R. No. 166/2008
Version as at 1 January 2009
Version No. 013
Dangerous Goods (Explosives) Regulations 2000
S.R. No. 61/2000
Version incorporating amendments as at 1 January 2009
Robens suggested two key issues were important in achieving high standards of safety.
What are these two key issue?
Where in the Act (or regulation) are these two issues addressed in the
mine safety legislation of your state/country?
In 1972, the British Robens report sought to modify the previous codes of practice using two base principals.
The first principle recognised the need to unify all the difference OHS laws under one system. It was proposed that this would be accomplished by creating "general duties" into one ruling (Robens Report, para 41).
The second principle observed that a self regulation model be implemented where workers and administrators 'come together' in order increase the standards of health and safety (Robens Report, para 41).
The Federal Government in 1985 passed legislation to form the then National Occupational Health and Safety Commission (NOHSC); though, because Australia is a federation, each state/territory has to ratify federal legislation in order to for the commission (NOHSC) to be apart of the Commonwealth and therefore have any legal grounds. Each state reformed OHS laws, based on the Robens model and beyond.
In fact, the OHS operates in a three way system. The first is the general duties which cover all employees regardless of job status (ie, contracted or not) and require the employee as practically possible to ensure a safe working environment. The second are the "provisions in regulations" are mandatory laws that are specific to each state. Finally, codes of practice are used as guidance which set the standards for the general duty of care. These help in setting standards the duty holder is required to identify the hazards and assess and control risks and therefore helps Robens second principle however there remains some critical gaps.
What is the main goal of industrial hygiene?
List the four key processes that play a role in achieving this goal.
Main goal of Industrial hygiene is risk reduction and/or risk elimination wherever possible.
Control of workplace environmental hazards
Define the following terms
Hazard: A hazard is any 'thing' that may cause harm or injury to a person or property. Also this is the potential of any agent or substances to cause harm, usually ill-health or disease.
Risk: The risk tells how likely an accident (An accident is any unexpected or unintended event that may cause harm or injury to a person or property) will cause harm or injury to a person or property. Risk is a function of the type of hazard times the amount of exposure (Risk = Hazard x Exposure)
Hazards management: The process of enacting general duties of care in order to eliminate, substitute, or reduce the likelihood of an accident (i.e. risk) through engineering or administrative solutions, or through applying personal protection equipment (PPE).
Risk Assessment: Risk Assessment is the process by which a specific risk is quantified or qualified in order to understand how to manage a specific hazard. It is based upon the effect that a specific hazard may have, the magnitude of the hazard (I,e, how severe it may be), and the duration that the hazard may impact a person or property. The risk assessment helps ascertain how a hazard may be managed and how a risk may be controlled.
Probability: the likelihood for an event to occur. One of the factors that serves as the dependant variable for risk (I.e. Risk=Probability * Severity) or
It is a way of expressing knowledge or belief that an event will occur or has occurred. In mathematics the concept has been given an exact meaning in probability theory, that is used extensively in such areas of study as mathematics, statistics, finance, gambling, science, and philosophy to draw conclusions about the likelihood of potential events and the underlying mechanics of complex systems.
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Frequency: Frequency is the rate at which a person may come into contact with a hazard over a defined length of time. Or The number of times that a periodic function repeats the same sequence of values during a unit variation of the independent variable
Severity: Severity is the magnitude, or intensity, with which a hazardous substance is exposed to a person. It is the dimension for classifying seriousness for Technical support issues.
Dose: Is the amount of the hazard which we are exposed. It is defined by the concentration of the hazardous substance times the length of time a person is exposed.
Dose is the concept of dose is paramount for occupational hygiene and risk management. Dose refers to the amount of a substance to which we are exposed, and is a combination of the concentration of exposure and duration of exposure.
Dose= concentration*duration of exposure
TLV values generally refer to a national exposure standard for a hazard (i.e. chemical, dust, or radiation). It is a means of quantifying the maximum concentrations of a particular substance in an area over a specified length of time, and then applying it as a standard for health and safety inspectors and duty carriers to use as a way of assessing risk.
TWA is an acronym for time weighted average. In this case, the duration of contaminant exposure is expressed over an eight hour working day and a five day working week. In this way, this exposure standard incorporates the maximum and minimum exposure rates a person experiences during a regular working day. The emphasis of an exposure free time is implicitly involved (as would be the case for noise) so that certain body thresholds are not passed.
STEL is an acronym for short term exposure limit. For some substances, a short term exposure standard is needed since acute and chronic health affects may result. Instead of an eight hour day, this exposure standard is measure over no more than fifteen minutes.
What are the main airborne contaminants/pollutants that can cause health-related problems at mine sites?
The Dust and particulates (arsenic, lead, mercury and etc);
The Toxic gases (carbon monoxide, sulphur dioxide and etc);
The Carcinogens (asbestos, aromatic hydrocarbons, and etc);
The Flammable gases (methane and carbon dioxide and etc);
The Radiation poison (radon, uranium, thorium and etc);
The Mixture of viruses and bacteria.
For a particular legal jurisdiction (state/country) what are the legal requirements for the concentration of the following in the general body of ventilation airflow (maximum or minimum)?
According to the HSIS
Pure oxygen: no restrictions
Oxygen diflouride: TWA=.05 ppm
Methane (as a gas)
Pure methane: TWA=0, STEL=0
Bromomethane: 5ppm STEL=0
In coal mines: TWA= 12,500 ppm STEL= 30000 ppm
Regular: TWA= 5000 ppm STEL= 30,000 ppm
Carbon monoxide: TWA= 30 ppm STEL=0
Hydrogen sulphide: TWA= 10 ppm STEL= 15ppm
Respirable dust (no silica)
Coal Dust: TWA = 3 mg/ m3 STEL=0
Soapstone: TWA = 3 mg/ m3 STEL=0
Vanadium: TWA = 0.05 mg/ m3 STEL=0
Graphite: TWA = 3 mg/ m3 STEL=0
Respirable dust (with silica): TWA= 2 mg/m3
Oxides of Nitrogen:
Nitrogen Triflouride: TWA= 10 ppm STEL=0
Nitrous Oxide: TWA= 25 ppm STEL=0
Nitric Oxide: TWA=25 ppm STEL=0
Nitrogen dioxide: TWA= 3ppm STEL=0
Nitrogen tetroxide: TWA= 0 STEL=0
Define Dust, list and briefly describe the general preventative measures, which can be used to control or prevent exposure to high dust exposures.
Dust caused by the mechanical disintegration of material can be defined as a collection of solid particles which:
Are dispersed in a gaseous medium (usually air)
Are able to remain suspended in the air for a relatively long time
Have a high surface area to volume ratio.
So briefly, over the entire range of airborne materials, dust generally has the largest particle size although it can exhibit a wide particulate range. In general, dust can be defined an amalgamation of various particulates (solid matter) that can separate and remain in suspension in air.
Dust is generally caused by mechanical weathering through, in the case of mines, the use of very large machines (drills and crushers) and blasts. Dust can either pose an immediate hazard (I,e, eye irritation) or long term health effects (radioactive particles that stick to respirable dust which are subsequently inhaled). Whether the effects are long term or short term, there are a number of ways that duty careers can control or even eliminate dust.
Preventative measures (Elimination):
This is the best way among all.
This includes watering to reduce dust formation when cutting and drilling; ensuring that cutting equipment is sharp, and using oils to transport mine cuts to an enclosed area.
Under these conditions, "the means of control" is through elimination.
A final piece of equipment is a blind hole borer which traps the dust generated through an enclosure.
This is an engineering means of control dust through a proper ventilation system.
Here the air must be able to be strong enough to pick up the heavy dust particles to reduce the amount of dust concentrating in the air or on the ground.
Dust extraction and filtration systems that pump in the 'dusty' air, filter out the particles and then expel 'cleaner' air.
Removal of employees (Administrative):
This is an administrative approach where the employees are basically removed from the hazard thereby eliminating exposure.
This is often not very practical, especially in medium/small operations, or in rural operations where all employees are needed, or working rotation is not an option.
Use of respirator (PPE):
This is the least way control however we have no other option.
Here a worker uses a respirator in order to filter out the dust, thereby minimising risk by reducing exposure.
However, many respirators can be too heavy or cumbersome to deal with, especially underground.
Discuss how methane is generated in mines. What are the key risks associated with methane, and how can the risks be managed?
Methane generation in mines:
This is produced by bacterial and chemical action on organic material and is evolved during both the formation of coal and petroleum. One of the most common strata gases. It is not toxic but is dangerous as it can form an explosive mixture with air. A methane/air mixture commonly called firedamp.
Methane is commonly associated with coal mines but it is also commonly found in other mines which are over or underlain by carbonaceous formations. Methane is retained within fractures, voids and pores within rock either as a compressed gas or adsorbed on mineral surfaces. When mining disturbs the rock the gas pressure gradient set up between the reservoir of methane and the ventilation system induces flow of methane along natural or mining induced fractures towards the opening.
Methane has no odour, but it is often accompanied by traces of heavier hydrocarbons in the paraffin series, which have a characteristic oily smell. The density of methane is a little over half that of air. This gives rise to the danger of methane layering in pools along the roof of underground openings. The buoyancy of methane can also cause problems in inclined workings.
Methane burns in air with a pale blue flame. The explosible range for methane in air is generally quoted as 5-15% with maximum explosibility at 9.8%. The lower limit remains fairly constant, the upper limit reduces as the oxygen content of air falls. To track the flammability of methane air mixtures a coward diagram as shown in figure 2 can be used. With relation to figure 1:coward
Figure 1: The coward diagram for methane in air.
In zone A the mixture is not flammable but is likely to become so if further methane is added.
In zone B the mixture is explosive and has a minimum nose value at 12.2% oxygen
Zones C and D illustrate mixtures that may exist in sealed areas.
Methane layers have two main hazards associated with them:
Layers extend the zones within which ignitions can occur
When an ignition occurs the methane layer acts as an effective fuse along which the flame can propagate, sometimes leading to much larger accumulations in roof cavities or in the gob.
Methane and Carbon dioxide (mixtures of the two gases) if mixed with nitrogen will make the dangers atmosphere. Because this associated with gas outbursts are:
Asphyxiation of miners by gas and dust. Compressed air lifelines may be maintained on or close to faces that are prone to outbursts.
The violence of the outburst may damage equipment, causing sparking that may ignite the highly flammable gas/dust mixture.
The sudden expansion of a large volume of gas can disrupt the ventilation system of the mine.
To control and Manage:
To control and manage the risk of Methane, first of all need to know the sources and nature of methane, and how the methane is releasing and migrating. And then understanding of risks can easily lead to learn of the methane risk management. The major systems as follows,
In its naturally occurring state in a coal seam, firedamp does not constitute an explosive risk. However, where firedamp released from adjacent seams meets "fresh-air" in the goaf, the firedamp is diluted and explosive mixtures (around 5% to 15% methane in air) are formed. Effective firedamp control is essential for safe working and involves providing either:
Face-End Ventilation and Gas Control : well designed Ventilation flow avoid the risk of methane gas.
Firedamp Drainage on Retreat Longwalls: Firedamp capture efficiencies on longwall faces typically lie between 60% and 80% of the total gas on advancing faces and from 30% to 60% of the total gas on retreat faces.
Alternatives and Supplements to Firedamp Drainage: There are ventilation options applicable to some retreat longwall coalfaces which can obviate the need for costly firedamp drainage. Such methods (eg. bleeder roads and sewer gate systems) are aimed at diverting gas away from working coalfaces along routes separate from those used to service the face.
Goaf Flushing: Goaf flushing has been used for temporarily amelioration of firedamp concentrations in a district return but it is not a recommended gas control solution. The method is generally applied to a fully-developed goaf (ie. where sufficient goaf has been created to form a substantial gas reservoir). The ventilation pressure across a district is reduced, after men have been withdrawn, allowing high gas concentration gas to migrate forward into the return airway. Transport activities in the main return may have to be suspended. Eventually, the equilibrium between gas flow into the waste and gas flow into the return is restored, the gas concentration in the district return being at a higher concentration than before due to the reduced air quantity. On restoring the original airflow, the gas is forced into the goaf, away from the face, thus reducing the emission into the return until equilibrium conditions are once again obtained. This approach is not advised due to the uncontrolled release of elevated firedamp concentrations into airways and across electrical equipment.
Methane Drainage: To produce gaseous fuel and/or to reduce methane emissions in to ventilation system its been used. Methane that is drained needs to be transported safely to the point of delivery, the infrastructure that is required to achieve this consists of the following: Pipe ranges, Monitors, Safety devices, Controls, Extractor pumps
Other than all above mentioned, in individual countries they are following up rules and regulations to control and manage the risk of Methane. Here is an example UK legislation states,
Electrical power must be switched off when the general body concentration of methane exceeds 1.25%.
If methane concentration exceeds 2% personnel other than those associated with improving the ventilation in the area should leave the area.
Discuss the sources and risks associated with arsenic, mercury and cyanides. How can the risks be managed?
Volatilization from oceans
Erosion of natural deposits
Estimated to be 1/3-2/3 of the total mercury released into the environment.
Stack losses from cinnabar roasting
The working and smelting of metals
Coal fired power plants
Discharges from mines, refineries and factories
Combustion of coal and municipal wastes, industrial wastes and boilers
Medical waste incinerators
Runoff from landfills/croplands
Can change form,
Cannot be destroyed
Cinnabar (HgS) is insoluble (and resists weathering);
Liquid Hg is slightly soluble in water.
Hg methylation forms CH3Hg+ which is easily absorbed by organisms and biomagnifies from the bottom to the top of the food chain
Bioaccumulates (concentrates) in muscle and tissue of fish and other wildlife
CH3Hg+ generally increases by a factor of ten or less with each step up the food chain
Arsenopyrite (FeAsS) is the most common arsenic mineral in ores and is also a byproduct associated with copper, gold, silver, and lead/zinc mining.
Arsenic trioxide (Fe2As3) is present in flue gases from copper ore roasting
coal-fired power plants and incinerators also may release As into atmosphere.
Water: average concentration is 1 ppb, but can be > 1,000 ppb in mining areas; As+5 most prevalent; many compounds dissolve in water.
Arsenic is a human carcinogen
In humans the primary target organs are the skin and vascular system
birds, animals, plants, and freshwater fish can become contaminated
Toxicity in water is determined by water temperature, pH, organic content, phosphate concentration, suspended soils, presence of oxidants, and speciation
Can leach from landfills and cyanide-containing road salts as well as to the atmosphere from car exhaust (hydrogen cyanide gas - HCN).
Some foods (almonds and lima beans) contain cyanides naturally
It can be produced by some bacteria, fungi, and algae
Spills: Cyanide and other heavy metal pollutants overflowed a dam at Baia Mare, Romania, contaminating 250 miles of rivers, and killing millions of fish
Most persistent in groundwater & at higher pH
Oral lethal dose of KCN for an adult is 200 mg
Airborne concentrations of 270 ppm is fatal
Long term exposure to lower levels results in heart pains, breathing difficulties, vomiting, blood changes, headaches and thyroid gland enlargement
CN does not bio-accumulate in fish
Cyanide risk Control Methods:
Production: Encourage responsible cyanide manufacturing by purchasing from manufacturers who operate in a safe and environmentally protective manner.
Transportation: Protect communities and the environment during cyanide transport.
Handling and Storage: Protect workers and the environment during cyanide handling and storage.
Operations: Manage cyanide process solutions and waste streams to protect human health and the environment.
Decommissioning: Protect communities and the environment from cyanide through development and implementation of decommissioning plans for cyanide facilities.
Worker Safety: Protect workers' health and safety from exposure to cyanide
Emergency Response: Protect communities and the environment through the development of emergency response strategies and capabilities.
Training: Train workers and emergency response personnel to manage cyanide in a safe and environmentally protective manner.
Daily inspection of leach residue storage ponds and tailings delivery pipelines;
Incident reporting and a system of emergency procedures;
Systems for data recording, evaluation, interpretation and reporting;
Process technician training and awareness of potential cyanide related problems, including personal safety and impacts on the surrounding natural environment;
systematic records management and documentation of animal mortalities;
Incorporating cyanide management procedures into the site Environmental Management Plan which is currently being updated.
Arsenic and mercury risk control methods:
The above mentioned methods are suited to adopt Arsenic and mercury as well. However in practical world, it depends upon the harmness, will vary to importances of handling.
Define the purpose of ventilation in underground mines. What types of ventilations systems are common?
The purpose for ventilation in mines is to dilute various forms of gases. These gases could be either a chemical hazard (as in carbon-monoxide and dust) or explosive physical hazards such as methane accumulation along the roofs of mine shafts.
Ventilation systems often come in the form of,
fans which control air flow
stoppages and seals will seal leakages in particular to older mines
Doors and airlocks
Regulators which is a door with an appropriate passage to maintain air pressure gradients
Aircrossings which allow suction and blowing ventilation systems to easily by pass one another and not allow for cross contamination
Electrical power is commonly employed in mines, what work practices would you define for the maintenance of electrical equipment?
Always to be Maintained, reviewed and modified mine power supply systems.
Make sure Consistently inspect machineraries and carry out tests for faults and hazards
Make sure always the electrical equipment is properly viewed, so that arrange some lights near electrical equipment in underground mines to ensure to be visible.
Make sure while Create procedures to ensure noise and electrical hazards; over voltages, current regulation, noise level reductions etc., are maintained to appropriate legislative standards.
Without too much stress, try to provide machinery that can be moved easily that are also within legislative requirements and can supply adequate electricity
Create an alternative power supply source in case of machinery breakdown which allows to do maintenance activities.
For the quick identification, install proper mine cables with appropriate colour coding system.
And following safety rules and regulations also makes the good work practices for the maintenance of electrical equipment.
Failure to exercise caution may result in injury, so caution must be used when operating or repairing electrical equipment
When performing electrical work, always use the proper protective equipment, such as: safety glasses, protective gloves, and a properly rated meter.
State regulations, Australian Standards and company policies are designed to guard against electrical hazards in the mining industry. So following up those are very essential
Wet conditions may corrode metal electrical components and cause their failure. Falling rock may damage an electrical cable or component. So need to avoid those kind of dangerous conditions before installing at specific places or need to take care to avoid those problems.
Exercise caution to be used to use proper protective equipment when working with batteries. Because batteries could explode and cause injury or could ignite and cause fires.
All have to be aware and especially all electrician properly trained to Be alert and knowledgeable of the hazards of electricity.
Make sure always keeping attitude tono electrical work can be performed until the electrical circuit is knocked, locked, and tagged.
Always make certain the frame ground is properly connected.
No electrical work shall be performed except by a qualified person. Circuit breakers and disconnects shall be marked for identification. Circuit breaking devices or proper fuses, shall be installed to protect against short circuit and overloads.
Disconnecting devices shall be locked and tagged out. All electrical equipment shall be examined, tested, properly maintained, and results recorded as required
Your mine employs pipelines to convey the following:
Run of mine drainage water
How would you ensure that each pipeline can be readily identified by a quick visual inspection?
Colouring the pipes with different kind of colours may give solution to this case.
Blue colour for service water
Red colour for Compressed air
Green colour for Methane
Yellow colour for mine drainage water
This way each pipe is easily visualised in the mine. A sign that demarcates the colour coding system will also be necessary to clarify the colour coding system.
Distinguish, with the use of examples, the difference between major, chronic and minor incidents. What are the legal requirements for reporting these different types of incidents in your jurisdiction?
Incident is a occurrence of an event that has a non human element to it (unlike accidents).
Major incidents: Are sudden changes which are dramatic, require immediate responses, and are generally costly and a number of fatalities. An example is methane gas outbursts in underground coal mines.
Major fire, explosion
Major equipment damage
Major loss of production
Typically cost millions of moneys
Chronic Incidents: Are events that result in an injury; is related to a number of causes, and have effects that are lower in magnitude and intensity than major incidents. Sometimes these events may cause alteration in the normal procedures in mines.
Recurring quality deviation.
Recurring equipment failure.
Slips, trips and falls.
Minor Incidents: Or near miss incidents which do not involved in any loss or injury but if a different event occurred, could cause injury or harm.
When these incidents happened, the legal requirement is 5 steps:
2. Gathering the Facts
3. Determine Cause(s)
4. Develop and Implement Corrective Action
5. Monitor and Review
Discuss four theories of accident causation.
It is developed by Herbert Hinrich (Travelers Insurance Co) in 1920.Says that injuries occur from actions that interact. The injuries are caused by unsafe acts by workers and are generally preventable given proper safety training.
Injuries arise from a set of complete actions
Most injuries arise from unsafe acts
Accidents are largely preventable
Unsafe acts can have later effects vs immediate
Management should take control
According to Heinrich, five factors can lead up to an accident:
Ancestry and social environment
Fault of a person
Unsafe mechanical or physical situations
The accident itself (falls, being hit)
Injury: Typically lacerations and fractures
Under this rubric, management should take control and provide safety to workers.
Human Factors Theory:
Accidents are caused by human error under three main factors:
Overload (imbalance in a persons capacity)
Inappropriate Response: How a person responds to a situation
Inappropriate Activity: Human error in judgment, action, direction, etc.)
Accident and Incident Theory:
Asper this theory, the environment is a cause instead of human error. The design and too high of expectation in work output are the causes of accidents. Therefore, there is an indirect influence of management and economic factors (deadlines, schedule, budget, peer pressure etc.) that can lead to bad judgment and therefore accidents. The Accident and Incident Theory proposes a causal relationship exists between management climate and focus, and accident causation.
Accidents are caused by
a) predisposition characteristics (cultural ,physical charecteristics,social norms)
b) Situational characterisitics (inadequate training, little guidance, or management "climate").
Under this theory there is a causation link between the environment and social or mental factors. The Epidemiology theory holds that models used for study and determination of disease can be utilized for accident causation as well
(a) What is occupational deafness?
A form of deafness due to the dysfunction of the auditory nerve, (i.e. hearing loss) that is caused by the overexposure to noise levels of high intensity). This is also called acoustic trauma deafness
Define the terms frequency, intensity, dB, db(A)
Frequency: The rate at which sound particles vibrate through an elastic medium that the ear can perceive as 'sound'.
Frequency = Cycles per Second = Hertz = Hz
1000 Hz = 1 Kilohertz = 1 kHz = Human Voice
Intensity: Intensity is the amount of energy travelling through a unit volume of air during a certain timeframe.
dB: The decibel (dB) is a logarithmic unit that indicates the ratio of a physical quantity (usually power or intensity) relative to a specified or implied reference level.
Amplitude = Loudness = Decibels = dB
60 dB = Average Speaking Voice
dB(A): It is the frequency response curve which is resembles the normal frequency hearing curve for most people. A meter using this network will give a result which does have some resemblance in level to that level which is experienced by most people
The other way we can say that, Noise is measured in decibels (dB) at a certain scale, such as A or C. The decibel scale is logarithmic. That means, with a 5dB exchange rate, 95 dB is 100% more noise than 90 dB.
Define the term Daily Noise Dose; what factors influence this?
Daily Noise Dose:
The Daily Noise is an exposure standard that measures the degree a person working is able to be exposed to noise. Worksafe states that a level of 85 dB(S) (ie non linear standard) over 8 hour day (much like the time weight average (TWA) exposure standard) should not be breached, nor a peak level of 140 dB at any specific time should not be breached (much like the TLV-STEL). If exposure to noise is to occur above these levels a measure of control upon noise is required.
According the National Institute for Occupational Safety - NIOSH - the daily dose level - D - should not equal or exceed 100.
When the daily noise exposure consists of periods of different noise levels, the daily dose can be calculated as:
D = ( te1 / td1 + te2 / td2 + ... + ten / tdn ) 100%Â Â Â Â Â Â Â Â Â (1)
D = daily noise exposure (%)
te = exposure time at a specified noise level
td = maximum duration time at a specified noise level
The daily dose can be converted to an 8-hr Time-Weighted Average -TWA by the formula
TWA = 10 log( D / 100 ) + 85Â Â Â Â Â Â Â Â (2)