ABRASIVE BLASTING TRAINING 280705 K.G.ppt

ABRASIVE BLASTING TRAINING 280705 K.G.ppt

1. HSES TRAINING CENTREHSES TRAINING CENTRE
ABRASIVE BLASTINGABRASIVE BLASTING

3. INTRODUCTION ‘FACT ‘ INTRODUCTION ‘FACT ‘
Abrasive blasters canAbrasive blasters can develop health problems develop health problems
from breathing in silica & lead dust.from breathing in silica & lead dust.
Silica is present in the various materials being Silica is present in the various materials being
used for blasting .used for blasting .
Old painted items can contains lead resulting in Old painted items can contains lead resulting in
lead poisoning. lead poisoning.
Sand has been banned in Europe and the USA Sand has been banned in Europe and the USA
for blasting and surface preparation . for blasting and surface preparation .

4. ObjectivesObjectives
The purpose of this training program is to The purpose of this training program is to
assist blasters on how to do abrasive blasting assist blasters on how to do abrasive blasting
safely.safely.
Removing barriers to successful prevention of Removing barriers to successful prevention of
silicosis, lead poisoning and other hazards.silicosis, lead poisoning and other hazards.
By providing employees and employers with By providing employees and employers with
information regarding the hazards of Grit, silica information regarding the hazards of Grit, silica
and possible control measures.and possible control measures.

5. TOPICSTOPICS
Definition of Abrasive blastingDefinition of Abrasive blasting
Selection of Abrasive blasting mediaSelection of Abrasive blasting media
Hazards involve in blasting workHazards involve in blasting work
Risk management – (Control measures and monitoring)Risk management – (Control measures and monitoring)
Supplied Air for Respiratory equipmentSupplied Air for Respiratory equipment
Personal Protective Equipment (PPE)Personal Protective Equipment (PPE)
House keepingHouse keeping
TrainingTraining
ConclusionConclusion

6. DEFINITION DEFINITION
Abrasive blastingAbrasive blasting
Abrasive blasting is the METHOD for removal of rust, Abrasive blasting is the METHOD for removal of rust,
scale, paint, graffiti, mildew, and various forms of scale, paint, graffiti, mildew, and various forms of
surface preparation. surface preparation.
Abrasive material is propelled on to the surface at high Abrasive material is propelled on to the surface at high
speed, using air pressure, water pressure, or speed, using air pressure, water pressure, or
centrifugal force.centrifugal force.

7. An abrasive is any powdered, granular, or solidAn abrasive is any powdered, granular, or solid
substance used to wear off the surface of materials insubstance used to wear off the surface of materials in
order to alter their shape or to supply a finish. order to alter their shape or to supply a finish.
Common natural abrasives include garnet and emery,Common natural abrasives include garnet and emery,
used for sandpaper; the quartz grains used inused for sandpaper; the quartz grains used in
sandblasting stone and metals; and pumice, which issandblasting stone and metals; and pumice, which is
used as a scouring material in soaps and some dentalused as a scouring material in soaps and some dental
pastes. pastes.
AbrasiveAbrasive

8. AbrasiveAbrasive
The most important synthetic abrasives are silicon carbide, The most important synthetic abrasives are silicon carbide,
known by its trade name known by its trade name CarborundumCarborundum, which is used for , which is used for
grinding nonferrous metals and nonmetallic materials; grinding nonferrous metals and nonmetallic materials;
aluminum oxide, a hard, steel-grinding abrasive; and aluminum oxide, a hard, steel-grinding abrasive; and
metallic abrasives such as iron and steel shot, steel wool, metallic abrasives such as iron and steel shot, steel wool,
and metallic grit. and metallic grit.
Natural or synthetic diamonds, the hardest of all abrasives, Natural or synthetic diamonds, the hardest of all abrasives,
are used in powdered form to grind or machine very hard are used in powdered form to grind or machine very hard
materials, including solid diamonds.materials, including solid diamonds.

9. SELECTING ABRASIVES SELECTING ABRASIVES
It is important to select an abrasive blasting media It is important to select an abrasive blasting media
with qualities that will generate minimum dust levels.with qualities that will generate minimum dust levels.
Metallic and garnet abrasives have proven Metallic and garnet abrasives have proven
characteristics that resist shattering on impact, which characteristics that resist shattering on impact, which
is the major cause of the dust produced during is the major cause of the dust produced during
blasting.blasting.
Environmentally clean and recyclable Environmentally clean and recyclable abrasives abrasives
such as garnet, chilled iron grit or cast steel grit such as garnet, chilled iron grit or cast steel grit
should be used where feasible.should be used where feasible.

10. BLASTING MEDIABLASTING MEDIA
Dry abrasive media which should not be usedDry abrasive media which should not be used
Materials containing more than 2% crystalline silicon Materials containing more than 2% crystalline silicon
dioxidedioxide
Materials which have not been recycled or treated to Materials which have not been recycled or treated to
remove respiratable dust , fines , contaminants .remove respiratable dust , fines , contaminants .
* River sand* River sand
* Beached sand* Beached sand
* Other white sand* Other white sand
* Quartz rock dust* Quartz rock dust
* Diatomaceous earth (pool filter material)* Diatomaceous earth (pool filter material)

11. Blast media which should not be used Blast media which should not be used
cont’…cont’…
Materials containing a radioactive substance:Materials containing a radioactive substance:
-Materials containing more than: (0.1% antimony, Materials containing more than: (0.1% antimony,
0.1% arsenic, 0.1% beryllium, 0.1% cadmium0.1% arsenic, 0.1% beryllium, 0.1% cadmium
0.5% chromium, 0.5% cobalt, 0.1% lead, 0.5% nickel).0.5% chromium, 0.5% cobalt, 0.1% lead, 0.5% nickel).
- Materials likely to harm the upper respiratory tract- Materials likely to harm the upper respiratory tract

12. Recommended Abrasives Recommended Abrasives
IlmeniteIlmenite
Aluminium oxideAluminium oxide
Garnet ( Natural )Garnet ( Natural )
Other rocks and mineral sands containing less than 2% Other rocks and mineral sands containing less than 2%
silica ?????silica ?????
Metal shotMetal shot
Steel gritSteel grit
Crushed glass , walnuts , plastics , sponge .Crushed glass , walnuts , plastics , sponge .
Sodium bicarbonateSodium bicarbonate
Coal slag , Copper slag . ( By products )Coal slag , Copper slag . ( By products )

13. HAZARDS IN BLASTING WORKHAZARDS IN BLASTING WORK
SilicosisSilicosis (exposure to silicon dust)(exposure to silicon dust)
The prime hazard in abrasive blasting is dust & The prime hazard in abrasive blasting is dust &
fines in particular silica dust. Prolonged inhalation fines in particular silica dust. Prolonged inhalation
of crystalline silica dust can cause silicosis of crystalline silica dust can cause silicosis

leadlead (common hazard when blasting old paint)(common hazard when blasting old paint)
When cleaning toxic metals such as lead, or when When cleaning toxic metals such as lead, or when
removing surface coatings containing lead, removing surface coatings containing lead,
mercury, arsenic, zinc and cadmium. mercury, arsenic, zinc and cadmium.

14. SilicosisSilicosis
Silicosis Silicosis is one of the oldest known is one of the oldest known
occupational disease is caused by the occupational disease is caused by the
inhalation of small particles of silica, or quartz inhalation of small particles of silica, or quartz
dust (silicon dioxide). dust (silicon dioxide).
In the lungs the particles are taken up by In the lungs the particles are taken up by
scavenging microphages, which then die and scavenging microphages, which then die and
accumulate near blood vessels. accumulate near blood vessels.
The connective tissue collagen forms around The connective tissue collagen forms around
these masses, producing fibrous nodules in these masses, producing fibrous nodules in
the lungs (pulmonary fibrosis). (silicon the lungs (pulmonary fibrosis). (silicon
tuberculosis) is also often deadly.tuberculosis) is also often deadly.

15. HAZARDS IN BLASTING WORKHAZARDS IN BLASTING WORK
Hazards from the blasting process include:Hazards from the blasting process include:
• • DustDust
• • Injury from flying debrisInjury from flying debris
• • Plant & Equipment (Blast Nozzle, Hose, BlastPlant & Equipment (Blast Nozzle, Hose, Blast
chamber & Ventilation)chamber & Ventilation)
• • Manual handlingManual handling
• • HeatHeat
• • NoiseNoise
• • Vibration Vibration
• • Working in confined spaceWorking in confined space
• • Fall & Tripping hazardFall & Tripping hazard

16. DUSTDUST
Risk factorsRisk factors
There are four risk factors with dust, and they are:There are four risk factors with dust, and they are:
the type of particulate involved and its biological effect;the type of particulate involved and its biological effect;
the concentration of airborne particulate in the the concentration of airborne particulate in the
breathing zone of the worker; breathing zone of the worker;
the size of the particles present in the breathing zone;the size of the particles present in the breathing zone;
the duration of exposure. the duration of exposure.

17. DustDust

18. Categories of dustCategories of dust
There are two categories of dust generated by abrasive There are two categories of dust generated by abrasive
blasting: blasting:
Inspirable dustInspirable dust - dust which a worker can inhale from the - dust which a worker can inhale from the
air in the work area.air in the work area.
It can contain a wide range of particles of different sizes It can contain a wide range of particles of different sizes
including particles which are too heavy to be inhaled and including particles which are too heavy to be inhaled and
captured by the respiratory system to very small particles of captured by the respiratory system to very small particles of
respirable size. respirable size.
Respirable dustRespirable dust - that portion of inspirable dust consisting - that portion of inspirable dust consisting
of very small particles of dust which can easily penetrate the of very small particles of dust which can easily penetrate the
lung down to the lower bronchioles and alveolar regions. lung down to the lower bronchioles and alveolar regions.
Abrasive blasting produces high levels of respirable dust. Abrasive blasting produces high levels of respirable dust.

19. Injury from flying debrisInjury from flying debris
During abrasive blasting operations workers can be struckDuring abrasive blasting operations workers can be struck
By particulate matter. Particulate matter is small particlesBy particulate matter. Particulate matter is small particles
or pieces of the substrate or blasting medium which areor pieces of the substrate or blasting medium which are
generated during abrasive blasting. generated during abrasive blasting.
Potential effectsPotential effects
Serious injuries can occur if the blasting medium isSerious injuries can occur if the blasting medium is
discharged under high pressure and substrate matter isdischarged under high pressure and substrate matter is
directed at high speed towards a person.directed at high speed towards a person.
eye damage; eye damage;
severe lacerations;severe lacerations;
burns; and burns; and
skin penetration. skin penetration.

20. Pressure vessels are operated only by persons trained in Pressure vessels are operated only by persons trained in
their use; their use;
All fittings are of equivalent rating to the pressure vessel All fittings are of equivalent rating to the pressure vessel
and are correctly attached; and are correctly attached;
Blow-down procedures are developed and implemented;Blow-down procedures are developed and implemented;
Where air supply is from a local air compressor an Where air supply is from a local air compressor an
electrical cut-off control is fitted and regularly checked; electrical cut-off control is fitted and regularly checked;
Safety relief valves are fitted and regularly checked.Safety relief valves are fitted and regularly checked.
Responsibilities of the employerResponsibilities of the employer

21. Control measures Control measures
Measures to control the risks from particulate matter include:-Measures to control the risks from particulate matter include:-
Carry out the abrasive blasting in a controlled ,cordoned Carry out the abrasive blasting in a controlled ,cordoned
enclosure or area separate from the workplace to reduce the enclosure or area separate from the workplace to reduce the
possibility of employees and others being struck by possibility of employees and others being struck by
particulate matter; particulate matter;
Installing guards / barriers / mesh to reduce the possibility of Installing guards / barriers / mesh to reduce the possibility of
particulate matter striking the immediate workforce.particulate matter striking the immediate workforce.
Ensuring, where practicable, that only one worker operates Ensuring, where practicable, that only one worker operates
one blast nozzle in one direction. one blast nozzle in one direction.
Workers exposed to particulate matter MUST wear and be Workers exposed to particulate matter MUST wear and be
supplied with the proper PPE equipment.supplied with the proper PPE equipment.
A blast nozzle must never be pointed at a person !!!A blast nozzle must never be pointed at a person !!!

22. Plant and equipment Plant and equipment
Abrasive blasting requires various plant to be operatedAbrasive blasting requires various plant to be operated
under pressure. These are air receivers after coolers,under pressure. These are air receivers after coolers,
blasting hoppers , pots , kettles, compressors . blasting hoppers , pots , kettles, compressors .
RESPONSIBILITIES OF THE EMPLOYER RESPONSIBILITIES OF THE EMPLOYER
Ensuring any air receiver or blasting hopper used at Ensuring any air receiver or blasting hopper used at
the workplace must be approved type. the workplace must be approved type.
In-service inspections are carried out in accordance In-service inspections are carried out in accordance
with the manufacturers’ specifications. with the manufacturers’ specifications.

23. Blast Machine (ASME Code)Blast Machine (ASME Code)

25. Blast nozzle Blast nozzle
The blast nozzle is a key piece of equipment in The blast nozzle is a key piece of equipment in
abrasive blasting.abrasive blasting.
It must be fitted with a” dead man handle “ or It must be fitted with a” dead man handle “ or
automatic cut-off device or electronic toggle switch.automatic cut-off device or electronic toggle switch.
This is particularly important if the operator This is particularly important if the operator
accidentally drops or loses control of the blast accidentally drops or loses control of the blast
nozzle. nozzle.

26. Blast nozzleBlast nozzle
An automatic cut-off device, An automatic cut-off device, ((dead-man control)dead-man control) should should
be used and maintained in accordance with the be used and maintained in accordance with the
manufacturer’s instructions. The controls must not be manufacturer’s instructions. The controls must not be
disabled or removed to allow continuous function. disabled or removed to allow continuous function.

27. Hoses Hoses
All hoses used for abrasive blasting should be specificallyAll hoses used for abrasive blasting should be specifically
designed for the purpose of abrasive blasting. designed for the purpose of abrasive blasting.
Abrasive blasting hoses should be:Abrasive blasting hoses should be:
made of impregnated carbon to prevent electric shock made of impregnated carbon to prevent electric shock
and fitted with an external visible earth wire or similar and fitted with an external visible earth wire or similar
earthing ( Grounding) system if they are made of any earthing ( Grounding) system if they are made of any
other material;other material;
fitted with hose whip checks or hose coupling safety fitted with hose whip checks or hose coupling safety
locks or both; locks or both;

28. Hoses cont.,Hoses cont.,
Kept as straight as possible. Long gradual curves Kept as straight as possible. Long gradual curves
should be used where hoses have to negotiate objects should be used where hoses have to negotiate objects
or equipment.or equipment.
Sharp curves may cause rapid wear on the hose Sharp curves may cause rapid wear on the hose
resulting in damage and possibly malfunction;resulting in damage and possibly malfunction;
Positioned in locations where they are not subjected to Positioned in locations where they are not subjected to
damage, fouling or restrictions such as from vehicles, damage, fouling or restrictions such as from vehicles,
buildings or fencesbuildings or fences

29. Hose, Hood & Apron

31. To protect the Environment,To protect the Environment, abrasive blasting to beabrasive blasting to be
carried out in a blasting chamber unless such a chambercarried out in a blasting chamber unless such a chamber
cannot reasonably be used because of the size, shape,cannot reasonably be used because of the size, shape,
position or location of the object being blasted. position or location of the object being blasted.

to be constructed of hard wearing non-combustible to be constructed of hard wearing non-combustible
material; material;

to be designed and maintained to prevent the escape of to be designed and maintained to prevent the escape of
dust and minimize internal projections where dust may dust and minimize internal projections where dust may
settle;settle;

minimum illumination of 200 lux, measured on a minimum illumination of 200 lux, measured on a
horizontal plane situated one meter above the floor;horizontal plane situated one meter above the floor;
Blast chambers Blast chambers

32. 
fixed in a metal sash; fixed in a metal sash;
•maintained to allow effective visibility; and maintained to allow effective visibility; and
•constructed of toughened safety glass, laminated constructed of toughened safety glass, laminated
safety glass; or safety wired glass.safety glass; or safety wired glass.
Two exits, a primary entrance and emergency exit, Two exits, a primary entrance and emergency exit,
both fitted with a quick release system.both fitted with a quick release system.

The emergency exit must be appropriately sign The emergency exit must be appropriately sign
posted and positioned at the furthermost point from posted and positioned at the furthermost point from
the main entrance. the main entrance.

An efficient mechanical ventilation system to be An efficient mechanical ventilation system to be
provided. provided.
Blast chambers cont., Blast chambers cont.,
To have inspection ports which are:To have inspection ports which are:

33. VentilationVentilation
The ventilation system must be constructed andThe ventilation system must be constructed and
maintained so that air is passed through a filtering ormaintained so that air is passed through a filtering or
cleaning device that removes airborne contaminantscleaning device that removes airborne contaminants
before discharge; before discharge;

a minimum air flow of 0.3 linear metres per second a minimum air flow of 0.3 linear metres per second
in the case of a blast chamber with a down-draft air in the case of a blast chamber with a down-draft air
flow; or flow; or

a minimum air flow of 0.4 linear metres per second, a minimum air flow of 0.4 linear metres per second,
in the direction of extraction, when a cross-draft air in the direction of extraction, when a cross-draft air
flow blasting chamber is used. flow blasting chamber is used.

34. The following should be considered as a means ofThe following should be considered as a means of
reducing the risk of heat stress to abrasive blastingreducing the risk of heat stress to abrasive blasting
operators:- operators:-
provision of personal protective equipment that is provision of personal protective equipment that is
appropriately selected and fitted to reduce build-up of appropriately selected and fitted to reduce build-up of
heat.heat.
cotton garments worn underneath may help in the cotton garments worn underneath may help in the
reduction of heat build-up; reduction of heat build-up;
cooling devices fitted to the air supply of blast helmets;cooling devices fitted to the air supply of blast helmets;
scheduling work aimed at countering the build-up of heat scheduling work aimed at countering the build-up of heat
inside personal protective equipment. inside personal protective equipment.
Control MeasuresControl Measures

35. 
job rotation (where alternative tasks in cool areas job rotation (where alternative tasks in cool areas
are available);are available);

appropriate breaks being provided to limit the time appropriate breaks being provided to limit the time
an operator works continuously, allowing the body an operator works continuously, allowing the body
to cool down; and to cool down; and

scheduling work in hours when ambient scheduling work in hours when ambient
temperatures are cooler; andtemperatures are cooler; and

cool drinking water being readily available. cool drinking water being readily available.
Control Measures cont’dControl Measures cont’d

36. VibrationVibration
Abrasive blasters are subject to hand-arm vibration Abrasive blasters are subject to hand-arm vibration
from the force of the abrasive.from the force of the abrasive.
Moving through the blast hose. Health effects Moving through the blast hose. Health effects
Prolonged use of abrasive blasting equipment may Prolonged use of abrasive blasting equipment may
lead to a condition known as white finger (dead finger lead to a condition known as white finger (dead finger
or Feynaud's phenomenon).or Feynaud's phenomenon).
It results from persistent microscopic damage to nerves It results from persistent microscopic damage to nerves
and blood capillaries. and blood capillaries.

37. Blanching and numbness in the fingers.Blanching and numbness in the fingers.
Decreased sensitivity to touch, temperature and pain. Decreased sensitivity to touch, temperature and pain.
Loss of muscular control. Chronic exposure may Loss of muscular control. Chronic exposure may
result in gangrenous.result in gangrenous.
Necrotic changes in the finger. There is no effective Necrotic changes in the finger. There is no effective
treatment to reverse the effects of white finger.treatment to reverse the effects of white finger.
SymptomsSymptoms

38. Elimination/substitution Elimination/substitution
The use of vibration-reduced equipment such as The use of vibration-reduced equipment such as
vibration isolating handles incorporated into blasting vibration isolating handles incorporated into blasting
nozzles may decrease the incidence of white finger.nozzles may decrease the incidence of white finger.
AdministrationAdministration
The length of time an operator is required to operate a The length of time an operator is required to operate a
blast nozzle should be kept to a minimum.blast nozzle should be kept to a minimum.
This may be achieved through job rotation or more This may be achieved through job rotation or more
frequent breaks.frequent breaks.
Frequent maintenance of equipment may also reduce Frequent maintenance of equipment may also reduce
the levels of vibration. the levels of vibration.
ControlsControls

39. Respiratory EquipmentRespiratory Equipment

40. Supplied air for respiratory equipmentSupplied air for respiratory equipment
Supplied air for respiratory equipment must be supplied Supplied air for respiratory equipment must be supplied
at a rate of at least 170 liters / min.at a rate of at least 170 liters / min.
It must contain at least 19.5% but not more than 22% It must contain at least 19.5% but not more than 22%
oxygen by volume.oxygen by volume.
It must be passed through a purifying device to ensure it It must be passed through a purifying device to ensure it
does not have an objectionable or nauseous odour.does not have an objectionable or nauseous odour.
The compressed air equipment: The compressed air equipment:
* must also have a thermostatically controlled * must also have a thermostatically controlled
interlock to cut off the air supply if it overheats. interlock to cut off the air supply if it overheats.

41. Supplied air for respiratory equipmentSupplied air for respiratory equipment
Breathing air hose connections must have a system to Breathing air hose connections must have a system to
prevent accidental disconnection and fittings that prevent accidental disconnection and fittings that
cannot be connected to other compressed air cannot be connected to other compressed air
equipment. equipment.
Breathing hoses should have non-toxic linings.Breathing hoses should have non-toxic linings.
Air lines and fittings should be inspected each day for Air lines and fittings should be inspected each day for
worn areas and leaks. Air lines should be routed as worn areas and leaks. Air lines should be routed as
straight as possible.straight as possible.
Do not place breathing air lines where vehicles can run Do not place breathing air lines where vehicles can run
over them.over them.
Eye and skin protection. Eye and skin protection.

42. PPEPPE

43. HousekeepingHousekeeping
Drift from abrasive blasting can be harmful not only to Drift from abrasive blasting can be harmful not only to
workers but also to others.workers but also to others.
Good housekeeping can minimize the risk of exposure.Good housekeeping can minimize the risk of exposure.
While other control measures should prevent dust While other control measures should prevent dust
escaping from the area where blasting is being done.escaping from the area where blasting is being done.
Any dust or residue that does make its way into the Any dust or residue that does make its way into the
workplace should be cleaned as soon as practical after workplace should be cleaned as soon as practical after
blasting has finished.blasting has finished.
Where practical, accumulated dust should be removed Where practical, accumulated dust should be removed
using wet cleaning methods, or High Efficiency using wet cleaning methods, or High Efficiency
Particulate Air (HEPA) filter vacuum methods. Particulate Air (HEPA) filter vacuum methods.

44. Training is ‘ Mandatory ’ Training is ‘ Mandatory ’
Proper training in selection of appropriate equipment and Proper training in selection of appropriate equipment and
safe working methods can reduce risk.safe working methods can reduce risk.
Induction and ongoing training must be given to any Induction and ongoing training must be given to any
worker exposed to risks from dust.worker exposed to risks from dust.
The training should be appropriate to the level of risk, as The training should be appropriate to the level of risk, as
identified by a risk assessment.identified by a risk assessment.
As a minimum, workers should be adequately trained in As a minimum, workers should be adequately trained in
safe methods of work and the safe use of plant and safe methods of work and the safe use of plant and
equipment.equipment.
Storage and maintenance of respiratory and other Storage and maintenance of respiratory and other
personal protective equipment.personal protective equipment.

45. CONCLUSIONCONCLUSION
1. 1. Elimination, the most desirable optionElimination, the most desirable option..
If you eliminate a hazard you completely eliminate the If you eliminate a hazard you completely eliminate the
associated risk.associated risk.
2. 2. SubstitutionSubstitution:-:-You can substitute something else (a You can substitute something else (a
substance or a process) that has less potential to cause substance or a process) that has less potential to cause
injury.injury.
3. 3. Isolation/ EngineeringIsolation/ Engineering:-:- You can make a structural You can make a structural
change to the work environment or work process to change to the work environment or work process to
interrupt the path between the worker and the risk.interrupt the path between the worker and the risk.

46. CONCLUSIONCONCLUSION
4. 4. AdministrativeAdministrative:-:- You may be able to reduce risk by You may be able to reduce risk by
upgrading training, changing rosters, or other upgrading training, changing rosters, or other
administrative actions.administrative actions.
5. 5. Personal protective equipment (the least desirable Personal protective equipment (the least desirable
optionoption).).
When you can't reduce the risk of injury in any other way, When you can't reduce the risk of injury in any other way,
use personal protective equipment (gloves, goggles, etc.) use personal protective equipment (gloves, goggles, etc.)
as a last resort.as a last resort.
In practice, several control options are often used in In practice, several control options are often used in
combination. This is particularly true in abrasive blasting, combination. This is particularly true in abrasive blasting,
with personal protective equipment usually used in with personal protective equipment usually used in
conjunction with other control measures.conjunction with other control measures.

47. Safety is a state of mind !!Safety is a state of mind !!