ILLUMINATION

Sufficient lighting must be provided, whether it is from a natural or artificial source, to allow safe movement around the workplace and to allow workers to perform their job without having to adopt awkward postures or strain their eyes to see.

Luminous flux

The luminous flux symbol is Ø, and the lumen (lm) is the flux unit n used in both the IES and SI systems. Luminous flux is the time flow rate of light energy. Flux is a power quantity in the same manner as horsepower. The unit of luminous flux, the lumen, is most frequently used to describethe lighting power of light sources

Lumen (unit)

The lumen (symbol: lm) is the SI unit of luminous flux, a measure of the perceived power of light. Luminous flux differs from radiant flux, the measure of the total power of light emitted,in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to differentwavelengths of light

Illuminance

Illuminance is the amount of light falling on a surface. The unit of measurement is lux (lx) and lumen /min2 the SI system (or lumens per square meter = 10.76 foot candles, fc). A light meter isused to measure it. Readings are taken from several angles and positions

Luminance

The amount of light reflected from a surface. The unit of measurement is candela per square meter (equals 0.29 foot-lamberts). An Illuminance meter is used to measure it. Severalmeasurements are made and averaged. Luminance tables are consulted for reference values

Place Minimum average illumination level lux

Pit bottoms 15-30Main junctions 12.5Roadways 4Haulage engines, control gear andhaulage drum

15

Noise

Sound is what we hear. Noise is unwanted sound.Noise pollution associated with mining may include noise from vehicle engines, loading and unloading of rock into steel dumpers, chutes, power generation, and other sources.

Effects of Noise

How noise affects will depend upon how long we are exposed to a sound, the loudness of the sound, and the ability of our body to recover after that exposure.

Temporary threshold shift

Temporary threshold shift (TTS) is a temporary loss of hearing. If we are exposed to a very noisy job, by the end of the shift we may have noticed a loss of hearing sensitivity. The greatest portion of temporary hearing loss occurs within the first two hours of exposure. The hair cells in our inner ear become exhausted from the excessive noise exposure and require more energy (decibels) before they will bend and send nerve impulses to the brain. This effect is “temporary” because the hair cells get a chance to rest while we are away from work, and by the next morning, they have recovered their sensitivity.

Permanent threshold shift

Permanent threshold shift is a permanent hearing loss that is very similar to the pattern of temporary hearing loss, except that we do not recover. Some of the hair cells are physically destroyed by the constant pounding and bending, leading to nerve loss. The more exposure to loud noise, the more hair cells is destroyed. This eventually leads to total deafness. Permanent loss does not respond to any known treatment or cure.

Tinnitus

Tinnitus is a ringing in the ears, similar to high-pitched background squealing with TVs and computers. It may accompany temporary and permanent hearing loss

HEAT STRESS

Heat stress is the broad term used to describe a range of health effects from mild symptoms to severe and life-threatening. Heatstress refers to the total heat load a person may be exposed to. This can be a combination of the heat generated by the person’s body;the air temperature and humidity; the radiant heat from the sun or from machines, processes or rock; plus clothing and PPE.

If it’snot controlled, excessive heat can cause discomfort, illness, and even death. In 2002 in the United States, two mine rescue trainers died from heat stress in an abandoned,unventilated, underground gold mine while under oxygen. The temperature was greater than 39 0C with very high humidity. The symptoms of heat stress can range from mild (heat rash or sunburn) to severe (heat exhaustion and heat stroke).

DUST CONTROL

Dust is a generic term used to describe fine particles that are suspended in the atmosphere. The term is non-specific with respect to the size, shape and chemical make-up of the particles.Mine Air pollution is the presence of high concentration of contaminations, dust, smokes etc., in the general body of Mine-air man breaths. Dust is defined as particulate matter as "any airborne finelydivided solid or liquid material with a diameter smaller than 100 micrometers.Dust associated with mining activity usually occurs as a result of the disturbance of fine particles derived from soil or rock. Dust formation is initiated by the disturbance of particles through mechanical action e.g. blasting, handling, transporting, in combination with air movement.

The consequences may include visible plumes and haze, the staining and soiling of surfaces, aesthetic or chemical contamination of water bodies or vegetation and, effects on personal comfort, amenity and health.Dust when inhaled can increase breathing problems, damage lung tissue, and aggravate existing health problems. In addition to health concerns, dust generated from various activities can reduce visibility, resulting in accidents.

'Inhalable fraction'—the mass fraction of total airborne particles which is inhaled through the nose and mouth.

'Respirable fraction'—the mass fraction of inhaled particles which penetrates to the unciliated airways

Health risks posed by inhaled dust particles are influenced by both the penetration and deposition of particles in the various regions of the respiratory tract and the biological responses to these deposited materials.The smaller the particles, the further they penetrate the respiratory tract.

Occupational Hazards / diseases due to expose in dusty and polluted air

There are certain diseases which are related to one’s occupation. These are caused by constant useof certain substances that sneak into air and then enter our body.

(i) Silicosis (Silico-tuberculosis) occurs due to inhalation of free silica, or SiO2 (Silicon dioxide), whilemining or working in industries related to pottery, ceramic, glass, building and construction work.The workers get chronic cough and pain in the chest. Silicosis treatment is extremely limitedconsidering a lack of cure for the disease. However, like all occupational respiratory ailments, it is100% preventable if exposure is minimized.

(ii) Asbestosisis caused by asbestos, which is used in making ceilings. It is also considered as cancer causing agent. Pathogenesis of the disease is characterized as progressive and irreversible, leading tosubsequent respiratory disability. In severe cases, asbestosis results in death from pulmonaryhypertension and cardiac failure.

(iii) Coal worker’s Pneumoconiosis occurs due to inhalation of coal dust from coal mining industry.Also referred to as black lung disease. The workers suffer from lung problems. Apart from asbestosis,black lung disease is the most frequently occurring type of pneumoconiosis. In terms of diseasepathogenesis, a time delay of nearly a decade or more occurs between exposure and disease onset.

Preventive Measures:

The most successful tool of prevention of respiratory diseases from industrial dust is to minimizeexposure. However, this is not a practical approach from the perspective of industries such asmining, construction/demolition, refining/manufacturing/processing, where industrial dust is anunavoidable byproduct. In such cases, industries must implement a stringent safety protocol that effectively curtails exposure to potentially hazardous dust sources.

Recognize when industrial dust may be generated and plan ahead to eliminate or control the dust at the source. Awareness and planning are keys to prevention of silicosis.

Do not use silica sand or other substances containing more than 1% crystalline silica as abrasive blasting materials. Substitute less hazardous materials.

Use engineering controls and containment methods such as blast-cleaning machines and cabinets, wet drilling, or wet sawing of silica-containing materials to control the hazard and protect adjacent workers from exposure.

Routinely maintain dust control systems to keep them in good working order. Practice good personal hygiene to avoid unnecessary exposure to other worksite contaminants

such as lead. Wear disposable or washable protective clothes at the worksite. Shower (if possible) and change into clean clothes before leaving the worksite to

preventcontamination of cars, homes, and other work areas. Conduct air monitoring to measure worker exposures and ensure that controls are providing

adequate protection for workers. Use adequate respiratory protection when source controls cannot keep silica exposures below the

designated limit. Provide periodic medical examinations for all workers who may be exposed to respirable

crystalline silica. Post warning signs to mark the boundaries of work areas contaminated with respirablecrystalline

silica. Provide workers with training that includes information about health effects, work practices,and

protective equipment for respirable crystalline silica. Report all cases of silicosis to Federal / State health departments.

Methane

Methane is highly explosive in concentrations of 5 to 15% and has been the cause of numerous mining disasters. It is best controlled by providing adequate air flow to dilute the gas to a level that isbelow its explosive range and to exhaust it quickly from the workings. Methane levels must becontinuously monitored and rules established to close down operations when its concentrationreaches 1 to 1.5% and to evacuate the mine promptly if it reaches levels of 2 to 2.5%.

Coal dust

In addition to causing black lung disease (anthracosis) if inhaled by miners, coal dust is explosivewhen fine dust is mixed with air and ignited. Airborne coal dust can be controlled by water spraysand exhaust ventilation. It can be collected by filtering re-circulating air or it can be neutralized bythe addition of stone dust in sufficient quantities to render the coal dust/air mixture inert.

Mechanical systems for controlling dust: Several mechanical equipment are used in cement manufacturing plant to control / collect dust. These are:

Dust collector - A dust collector (bag house) is a typically low strength enclosure that separates dust from a gas stream by passing the gas through a media filter. The dust is collected on either the inside or the outside of the filter. A pulse of air or mechanical vibration removes the layer of dust from the filter. This type of filter is typically efficient when particle sizes are in the 0.01 to 20 micron range.

Cyclone - Dust laden gas enters the chamber from a tangential direction at the outer wall of the device, forming a vortex as it swirls within the chamber. The larger articulates, because of their greater inertia, move outward and are forced against the chamber wall. Slowed by friction with the wall surface, they then slide down the wall

into a conical dust hopper at the bottom of the cyclone. The cleaned air swirls upward in a narrower spiral through an inner cylinder and emerges from an outlet at the top. Accumulated particulate dust is deposited into a hopper, dust bin or screw conveyor at the base of the collector. Cyclones are typically used as pre-cleaners and are followed bymore efficient air-cleaning equipment such as electrostatic precipitators and bag houses.

Electrostatic Precipitator - In an electrostatic precipitator, particles suspended in the air streamare given an electric charge as they enter the unit and are then removed by the influence of anelectric field. A high DC voltage (as much as 100,000 volts) is applied to the discharge electrodes tocharge the particles, which then are attracted to oppositely charged collection electrodes, on whichthey become trapped. An electrostatic precipitator can remove particulates as small as 1 μm(0.00004 inch) with an efficiency exceeding 99 percent.

Dust collection system - Dust collection systems use ventilation principles to capture the dust filled air-stream and carry it away from the source through ductwork to the collector. A typical dustcollection system consists of four major components, such as (1) An exhaust hood to capture dustemissions at the source; (2) Ductwork to transport the captured dust to a dust collector; (3) A dustcollector to remove the dust from the air; (4) A fan and motor to provide the necessary exhaustvolume and energy.

Wet dust suppression system - Wet dust suppression techniques use water sprays to wet thematerial so that it generates less dust. There are two different types of wet dust suppressions:

(i) Wets the dust before it is airborne (surface wetting) and

(ii) Wets the dust after it becomes airborne. In many cases surfactants or chemical foams are oftenadded to the water into these systems in order to improve performance.

Airborne dust capture system - Airborne dust capture systems may also use a water-spray technique; however, airborne dust particles are sprayed with atomized water. When thedust particles collide with the water droplets, agglomerates are formed. Theseagglomerates become too heavy to remain airborne andsettle. Airborne dust wetsuppression systems work on the principle of spraying very small water droplets intoairborne dust. When the small droplets collide with the airborne dust particles, they stick toeach other and fall out of the air to the ground. Research showed that, if a sufficient numberof water droplets of approximately the same size as the dust particles could be produced,the possibility of collision between the two would be extremely high. It was also determinedthat if the droplet exceeded the size of the dust particle, there was little probability ofimpact and the desired precipitation. Instead, the dust particle would move around thedroplet.

The Hazard and Risk Management Process

The process should be as follows:

a. Identification of hazards and associated risks

b. Assessment of the hazard and associated risks

c. Determine what controls are required to manage the hazard and associated risks

d. Develop a recovery plan to prevent escalation if the controls fail

e. Monitor and review controls for effectiveness

Any measures used to control the hazard or risks posed by a hazard should be based on information obtained from the hazard assessment. The hazard controls shall:

Follow the hierarchy of control set out in the Health and Safety in Employment Act.

a. Eliminate

b. Isolate

c. Minimize

The hazard control element of the hazard management process should:

d. Set out the measures to be taken to prevent the people coming into contact with hazard

e. Provide for the identification and maintenance of hazard control zones between areas ofwork and each identified potential hazard if appropriate

f. Include any special systems of working developed for the hazard.

g. Include any assumptions made in the development of measures to control hazards andtheir risks

h. Be maintained so that the best available knowledge of the risks control at the operation isat all times in practice

i. Be reviewed and if required updated before the operation is developed into any new area