nebosh occupational health hazards by terry robson
TRANSCRIPT
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NEBOSH NATIONAL
GENERAL CERTIFICATE
Occupational health hazards
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LEARNING OUTCOMES (I)
classification of occupational health hazards
(physical, chemical, biological, ergonomic)
commonly occurring occupational diseases andconditions arising from exposure to physical,
chemical, biological and ergonomic hazards
meaning of terms; toxic, harmful, corrosive,
irritant and the response of the body to substances
with these properties
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LEARNING OUTCOMES (II)
the main routes of entry of hazardous substances
into the body
the significance of the form taken by a hazardoussubstance ie gas, vapour, mist, aerosol, smoke
fume, dust, liquid and solid
the concept of target organs and target systems
occupational exposure limits; distinction between
MELs and OESs
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LEARNING OUTCOMES (III)
general principles and methods of air monitoring
methods that can be used for prevention and
control of hazardous substances, with particularreference to workplace ventilation systems
main requirements of the Control of Substances
Hazardous to Health Regulations 1994
precautions needed during the storage, transport,
use and disposal of dangerous substances
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GENERAL ASPECTS OF
OCCUPATIONAL HEALTH
& HYGIENE
what types of agent might represent an
occupational health risk in the workplace?
how do we go about evaluating the severity
of the risk?
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PRINCIPLES OF
OCCUPATIONAL HYGIENE Recognition/identificationof occupational
health hazards
Measurementof level or concentration
Evaluationof likelihood and severity of
harm Control strategiesavailable to reduce or
eliminate risk
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RECOGNITION
chemicalliquids, fumes, mists vapours, gases, dusts
physicalradiation, noise, vibrations, temperature,
humidity
biological
bacteria, viruses, fungi ergonomic
body position, repetitive actions, work pressure
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CHEMICAL HAZARDS
absorption then attack on organs or
metabolic processestoxic response
carcinogenic response
contact then attack on the surface of thebody
corrosive/irritant response
dermatitic/sensitisation response
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BIOLOGICAL HAZARDS
exposure to biological agents resulting in
illness
types of biological agent include
bacteria
viruses
fungi
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PHYSICAL HAZARDS
harmful energy absorbed by the bodys
structure energy derived from
mechanical sources
noise, vibration
radiation sources
ionising, non-ionising
thermal sources
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ERGONOMIC HAZARDS
concerns the physical, physiological and
psychological relationships between peopleand work
specific areas include
perceptual responses
work rates and fatigue
man-machine interface
anthropometrics
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MEASUREMENT
continuously
control strategy where the risk is high
intermittently
initial determination of hazard
spot measurement in an established process
routine check measurement
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EVALUATION
harmful characteristics of the substance,
energy or condition involved
concentration, intensity orlevel of the
exposure to the harmful agent
time duration of the exposure
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CONTROL
elimination
substitution
change of work method
change of work pattern
isolation and segregation engineering controls
personal protective equipment
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ROUTES OF ATTACK ON
THE HUMAN BODY
route of entry
(reach an area of penetration of the
body)
process of entry(penetrate the outer cover of the body)
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ROUTES OF ENTRY
inhalation
ingestion
skin pervasion
injection
implantation aspiration
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PROCESS OF ENTRY
absorption
epidermislungs
gastro-intestinal tract
direct entry into the body
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TOXICOLOGY- the study of poisonous materials and their effects
on living organisms
toxic substances
systemic
travel through thesystem
local
act only at the point ofcontact
cumulative not readily excreted
from the body
accumulated over aperiod of time
toxicity
LD50 to quantify the
effects of a toxic agentAcute Toxicity
harmful effect occurs
quickly (seconds,
minutes, hours)
Chronic Toxicity
harmful effect takes a
long time to appear
(months, years)
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LOCAL AND SYSTEMIC
EFFECTS local effects
(confined to specific
area where contactoccurs)
skin
eye
respiratory tract
systemic effects
(occur at organs
distant from contactsite)
liver
nervous system
bone
blood-forming organs
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DEFENCE MECHANISMS
OF THE BODY respiratory defence
physical filtration
phagocytosis
lachrymation
immune response
inflammatory response
fibrotic response
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CHIP 2
Chemicals (Hazard Information and
Packaging for Supply) Regulations
1994
category of danger
indication of danger
symbol
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HEALTH EFFECTS
CLASSIFICATION OF
HAZARDOUS SUBSTANCES
very toxic
toxic
harmful
corrosive
irritant
sensitising
carcinogenic
mutagenic
toxic for
reproduction
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APPROVED SUPPLY LIST
general nature of the risk
(risk phrase)
causes severe burns precautions to be taken
(safety phrase)
keep out of reach of children
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LABELLING
supplier information
name of substances or constituents
indication of danger
symbol
risk phrase
safety phrase
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SAFETY DATA SHEETS
composition
hazards
first aid fire fighting
accidental release
handling/storage exposure controls
personal protection
physical properties
chemical properties stability/reactivity
toxicology
ecological information disposal
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CATEGORIES OF
CHEMICAL AGENT
toxic, including carcinogenic
corrosive and irritant
dermatitic and sensitising
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FORMS OF CHEMICAL
AGENT
solids
liquids
dusts
fibres
mists
gases
fumes
vapours
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TYPES OF TOXIC EFFECT
respiratory irritants
chemical asphyxiants
haemolytic poisons narcotics
nervous systempoisons
metallic poisons
metallic and polymerfume fever
carcinogens
halogenatedcompounds
nitro-compounds
aromatic amines
polycyclic aromatichydrocarbons
natural carcinogens inorganic carcinogens
benzene
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TOXIC AGENTS
physical form(s)
mode of entry to body
target organs symptoms of exposure
acute
chronic occupations at risk
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COMMONLY OCCURRING
TOXIC SUBSTANCES lead
mercury
benzene
phenol
trichloroethylene
silaceous dust
asbestos
carbon monoxide
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CORROSIVE AGENTS
destroy living tissue
acids and alkalis
injury through
contact with skin and eyes
inhalation
ingestion
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DERMATITIC AGENTS
primary cutaneous irritants
contact dermatitis
at site of contact
recovery on removal of agent
cutaneous sensitisers
sensitisation dermatitis
initial sensitisation
trace contact enough to cause reoccurrence
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SENSITISERS
respiratory system
occupational asthma
inhalation of antigen causes bronchialconstriction
sensitisation dermatitis
isocyanatestrace contact enough to cause reoccurrence
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OCCUPATIONAL
EXPOSURE LIMITS (I) designed to control the absorption of
airborne contaminants into the body
measured in:ppm (parts of vapour/gas per million parts of air)mg/m3 (milligrams of substance per cubic metre of
air)
expressed as the concentration of an airbornesubstance averaged over a reference period15 minutes short term limit
8 hours long term limit
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OCCUPATIONAL
EXPOSURE LIMITS (II) Maximum Exposure
Limit (MEL)
maximum permissible
concentration
has legal status
must not be exceeded
reduce exposure to as farbelow the MEL as
possible
Occupational Exposure
Standard (OES)
concentration at which
no evidence of harm
represents good practice
if exceeded, take steps to
reduce down to OES
OES represents adequate
control
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OCCUPATIONAL
EXPOSURE LIMITS (III) long term limits
time-weighted average
concentration conc. x exposure time
averaged over 8 hours
designed to control
chronic effects
short term limits
time-weighted average
concentration conc. x exposure time
averaged over 15 mins
designed to control
acute effects
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SAMPLING OF AIRBORNE
CONTAMINANTS (I)
Purpose
qualitative analysis
indicate presence ofand identity of contaminants
quantitative analysis
measure concentration and assess compliance
with standards
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SAMPLING OF AIRBORNE
CONTAMINANTS (II) Types
spot or grab sample (stain tube)
taken at a single point at a particular time in thegeneral working atmosphere eg ozone monitoring
time averaged sample (dust sampling) taken over a period of time, analysed, and averaged
over that period (operators breathing zone)
continuous monitoring (direct reading) continually measured and giving a continuous
record of airborne contamination (can be used inconjunction with alarm systems eg toxic chemicals)
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CONTROL PHILOSOPHY
Source Transmission Receiver
Elimination Shielding Remove worker
Substitution Distance Reduce exposure
Enclosure Dilution ventilation Enclose worker
Process change Reduce no of
workers
LEV Personal protective
equipment
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VENTILATION
dilution ventilation
dilutes contaminant to
an acceptable level comprises fans set in
walls or roof
cheap and simple
limited application as a
control strategy
local exhaustventilation
captures contaminant
close to point ofgeneration
comprises hood,ductwork, filter,
fan,outlet good control of
hazardouscontaminants
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DILUTION VENTILATION
(I) changes the whole workplace air over a
given time period ie air changes per hour
limit to circumstances where:exposure limit is high
low evaporation rate for liquids
slow evolution for gases
operators not close to the point of generation
substance is quickly carried away from theoperator
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DILUTION VENTILATION
(II) rate of contaminant generation governs air
changes per hour required
density of contaminant governs position offans:density >1 (ie solvents) - low level fan in wall
density
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LOCAL EXHAUST
VENTILATION (I) Hood or exhaust inlet
receptor hood
contaminant directed into a large hood by fanassisted draught
captor hood
contaminant captured by air flow close to point of
generation low pressure large volume flow
high pressure low volume flow (high velocity)
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LOCAL EXHAUST
VENTILATION (II) ducting
straight with gentle bends and angled joints
sufficient air flow to prevent deposition ofsolids
access ports for cleaning and flow monitoring
filter or purifying systemcyclones, washers, electrostatic, bag filters
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LOCAL EXHAUST
VENTILATION (III) Fans
axial flow fan airflow is parallel to the shaft of the impeller
compact and fits neatly into ductwork
centrifugal fan air enters the impeller then is discharged at right
angles
exhaust outletcareful location to avoid:
cyclic pollution
effects of weather of air disturbance
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BIOLOGICAL HAZARDS
zoonosesanimal infections transmitted to persons in the
course of their work
bacilli infections such as Legionnaires or Weils
disease
fungiextrinsic allergic alveolitis
blood-borne infectionshepatitis B and AIDS
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ZOONOSES
Brucellosis (bacterium)
cattle, pigs
Q Fever (bacterium)
cows, sheep
Orf(virus)
sheep
Psitticosis (bacterium)
poultry, birds
Anthrax (bacterium)
farm animals
Glanders
horses, donkeys, mules
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CONTROL STRATEGIES
FOR ZOONOSES routes of entry
skin penetration
cuts, sores, abrasions
injection by bites contact with
conjunctiva of eye
inhalation
contaminated dust
ingestion contamination via hands
control strategies eliminate
immunisation
improve animal stock enclosure
infected aerosols
ventilation infected dusts from
wool, skin, hides hygiene disinfection
personal protectiveequipment
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LEGIONNAIRES DISEASE
caused by inhalation of airborne dropletscontaining the legionella bacteria
pneumonia-type symptoms
manage the risk by:
identifying and assessing sources of exposure
contaminated sprays and aerosols
avoid conditions where legionella can proliferate(water temperature,stagnation, treatment)
persons at risk
susceptible persons ie hospital patients
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WEILS DISEASE
caused by infection from rats
type of bacteria (Leptospira icterohaemorrhagiae)
enters body through cuts/abrasions of skin
jaundice-type symptoms
manage the risk by:
identifying and assessing sources of exposure
destruction of rat infestation immunisation, first aid, information, protective clothing
persons at risk
canal workers, sewer workers, abattoir workers
BLOOD BORNE
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BLOOD-BORNE
INFECTIONS
hepatitis B (virus)
severe form of jaundice
infection through
contact with blood orbodily fluids
persons at risk includehealth workers andemergency services
protect throughpreventing puncturewounds, disinfectionand disposable gloves
AIDS (virus) debility of immune
system
infection throughcontact with blood orbodily fluids
persons at risk includehealth/social workersand emergency
servicesprotect through
preventing puncturewounds, disinfectionand disposable gloves
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SUBSTANCES HAZARDOUS
TO HEALTH classified as dangerous to health under the
current CHIP Regulations
assigned a MEL or OES
biological agent
dust in a substantial concentration
any other substance which creates a
comparable health hazard
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REQUIREMENTS OF
COSHH assess the risks to health arising from exposure
prevent or adequately control exposure
ensure that control measures are used andproperly maintained
monitor exposure and carry out appropriate
health surveillance ensure that employees are properly informed,
trained and supervised
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COSHH ASSESSMENT (I)
which hazardous substances are present?
brought into the workplace
dusts, fumes, leakages finished products or wastes
who might be exposed?
employeescontractors
public
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COSHH ASSESSMENT (II)
do they represent a significant risk?
hazardous properties (toxic, corrosive, irritant)
quantity used and frequency of usepossible routes of exposure (inhalation, contact)
possibility of exposure exceeding OEL
possibility of leakage, spillage or release
cleaning and maintenance operations
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PREVENTING EXPOSURE
change the process or activity
the hazardous substance is not required or
generated
replace the hazardous substance with a safer
alternative use the hazardous substance in a safer form
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CONTROLLING EXPOSURE
totally enclose the process
partially enclose the process and use local
exhaust ventilation
use general ventilation
use systems of work and handling
procedures that minimise spills and leaks
reduce the duration of exposure
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MONITORING EXPOSURE
HEALTH SURVEILLANCE monitoring exposure
where serious risks if
controls fail
to confirm exposure
limits are not exceeded
to confirm that controls
are working properly
keep records
health surveillance
where exposure is
linked to a disease
which could occur and
can be detected
where employees are
working in a process
listed in schedule 5 andexposure could be
significant
RECORDING AND
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RECORDING AND
REVIEWING THE
ASSESMENT record enough
information:
to show how decisions
on risks and
precautions were made
to clearly show the
responsibilities forimplementing the
precautions
review theassessment:
at no less than 5-yearlyintervals
whenever it is thoughtthat the assessmentmight not be valid
where there has been asignificant change inthe work
INFORMATION
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INFORMATION,
INSTRUCTION AND
TRAINING inform, instruct and train employees about:
the nature of the substances and the risks
arising from exposurethe precautions that should be taken
give information and instruction on:
the purpose and use of control measuresuse of personal protective equipment
results of any monitoring or health surveillance
emergency procedures
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DISPOSAL OF HAZARDOUS
SUBSTANCES (I) Safe Storage
segregate
control storage to prevent risks to employeesand others
keep hazardous and non-hazardous wasteseparate
ensure correct labellingkeep quantities to a minimum
separate incompatible hazardous wastes
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DISPOSAL OF HAZARDOUS
SUBSTANCES (II) Transport
use correct type ofvehicle
inspect load prior totransport to check:
description of material
containment
labelling
documentation
transfer waste only toan authorised person
transfer must beaccompanied by
written documentation: identification
quantity
time and place oftransfer
details of current andintended holder
special waste requiresuse of a consignmentnote