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NEBOSH NATIONAL GENERAL CERTIFICATE

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Title: NEBOSH NATIONAL GENERAL CERTIFICATE


1
NEBOSH NATIONAL GENERAL CERTIFICATE
  • Occupational health hazards

2
LEARNING OUTCOMES (I)
  • classification of occupational health hazards
    (physical, chemical, biological, ergonomic)
  • commonly occurring occupational diseases and
    conditions 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

3
LEARNING OUTCOMES (II)
  • the main routes of entry of hazardous substances
    into the body
  • the significance of the form taken by a hazardous
    substance 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

4
LEARNING OUTCOMES (III)
  • general principles and methods of air monitoring
  • methods that can be used for prevention and
    control of hazardous substances, with particular
    reference 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

5
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?

6
PRINCIPLES OF OCCUPATIONAL HYGIENE
  • Recognition/identification of occupational health
    hazards
  • Measurement of level or concentration
  • Evaluation of likelihood and severity of harm
  • Control strategies available to reduce or
    eliminate risk

7
RECOGNITION
  • chemical
  • liquids, fumes, mists vapours, gases, dusts
  • physical
  • radiation, noise, vibrations, temperature,
    humidity
  • biological
  • bacteria, viruses, fungi
  • ergonomic
  • body position, repetitive actions, work pressure

8
CHEMICAL HAZARDS
  • absorption then attack on organs or metabolic
    processes
  • toxic response
  • carcinogenic response
  • contact then attack on the surface of the body
  • corrosive/irritant response
  • dermatitic/sensitisation response

9
BIOLOGICAL HAZARDS
  • exposure to biological agents resulting in
    illness
  • types of biological agent include
  • bacteria
  • viruses
  • fungi

10
PHYSICAL HAZARDS
  • harmful energy absorbed by the bodys structure
  • energy derived from
  • mechanical sources
  • noise, vibration
  • radiation sources
  • ionising, non-ionising
  • thermal sources

11
ERGONOMIC HAZARDS
  • concerns the physical, physiological and
    psychological relationships between people and
    work
  • specific areas include
  • perceptual responses
  • work rates and fatigue
  • man-machine interface
  • anthropometrics

12
MEASUREMENT
  • continuously
  • control strategy where the risk is high
  • intermittently
  • initial determination of hazard
  • spot measurement in an established process
  • routine check measurement

13
EVALUATION
  • harmful characteristics of the substance, energy
    or condition involved
  • concentration, intensity or level of the exposure
    to the harmful agent
  • time duration of the exposure

14
CONTROL
  • elimination
  • substitution
  • change of work method
  • change of work pattern
  • isolation and segregation
  • engineering controls
  • personal protective equipment

15
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)

16
ROUTES OF ENTRY
  • inhalation
  • ingestion
  • skin pervasion
  • injection
  • implantation
  • aspiration

17
PROCESS OF ENTRY
  • absorption
  • epidermis
  • lungs
  • gastro-intestinal tract
  • direct entry into the body

18
TOXICOLOGY- the study of poisonous materials and
their effects on living organisms
  • toxicity
  • LD50 to quantify the effects of a toxic agent
  • Acute Toxicity
  • harmful effect occurs quickly (seconds, minutes,
    hours)
  • Chronic Toxicity
  • harmful effect takes a long time to appear
    (months, years)
  • toxic substances
  • systemic
  • travel through the system
  • local
  • act only at the point of contact
  • cumulative
  • not readily excreted from the body
  • accumulated over a period of time

19
LOCAL AND SYSTEMIC EFFECTS
  • local effects (confined to specific area
    where contact occurs)
  • skin
  • eye
  • respiratory tract
  • systemic effects (occur at organs distant from
    contact site)
  • liver
  • nervous system
  • bone
  • blood-forming organs

20
DEFENCE MECHANISMS OF THE BODY
  • respiratory defence
  • physical filtration
  • phagocytosis
  • lachrymation
  • immune response
  • inflammatory response
  • fibrotic response

21
CHIP 2
  • Chemicals (Hazard Information and Packaging for
    Supply) Regulations 1994
  • category of danger
  • indication of danger
  • symbol

22
HEALTH EFFECTS CLASSIFICATION OF HAZARDOUS
SUBSTANCES
  • very toxic
  • toxic
  • harmful
  • corrosive
  • irritant
  • sensitising
  • carcinogenic
  • mutagenic
  • toxic for reproduction

23
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

24
LABELLING
  • supplier information
  • name of substances or constituents
  • indication of danger
  • symbol
  • risk phrase
  • safety phrase

25
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

26
CATEGORIES OF CHEMICAL AGENT
  • toxic, including carcinogenic
  • corrosive and irritant
  • dermatitic and sensitising

27
FORMS OF CHEMICAL AGENT
  • solids
  • liquids
  • dusts
  • fibres
  • mists
  • gases
  • fumes
  • vapours

28
TYPES OF TOXIC EFFECT
  • respiratory irritants
  • chemical asphyxiants
  • haemolytic poisons
  • narcotics
  • nervous system poisons
  • metallic poisons
  • metallic and polymer fume fever
  • carcinogens
  • halogenated compounds
  • nitro-compounds
  • aromatic amines
  • polycyclic aromatic hydrocarbons
  • natural carcinogens
  • inorganic carcinogens
  • benzene

29
TOXIC AGENTS
  • physical form(s)
  • mode of entry to body
  • target organs
  • symptoms of exposure
  • acute
  • chronic
  • occupations at risk

30
COMMONLY OCCURRING TOXIC SUBSTANCES
  • lead
  • mercury
  • benzene
  • phenol
  • trichloroethylene
  • silaceous dust
  • asbestos
  • carbon monoxide

31
CORROSIVE AGENTS
  • destroy living tissue
  • acids and alkalis
  • injury through
  • contact with skin and eyes
  • inhalation
  • ingestion

32
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

33
SENSITISERS
  • respiratory system
  • occupational asthma
  • inhalation of antigen causes bronchial
    constriction
  • sensitisation dermatitis
  • isocyanates
  • trace contact enough to cause reoccurrence

34
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 airborne
    substance averaged over a reference period
  • 15 minutes short term limit
  • 8 hours long term limit

35
OCCUPATIONAL EXPOSURE LIMITS (II)
  • Maximum Exposure Limit (MEL)
  • maximum permissible concentration
  • has legal status
  • must not be exceeded
  • reduce exposure to as far below 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

36
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

37
SAMPLING OF AIRBORNE CONTAMINANTS (I)
  • Purpose
  • qualitative analysis
  • indicate presence of and identity of contaminants
  • quantitative analysis
  • measure concentration and assess compliance with
    standards

38
SAMPLING OF AIRBORNE CONTAMINANTS (II)
  • Types
  • spot or grab sample (stain tube)
  • taken at a single point at a particular time in
    the general 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 in
    conjunction with alarm systems eg toxic
    chemicals)

39
CONTROL PHILOSOPHY
40
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 exhaust ventilation
  • captures contaminant close to point of generation
  • comprises hood, ductwork, filter, fan,outlet
  • good control of hazardous contaminants

41
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 the
    operator

42
DILUTION VENTILATION (II)
  • rate of contaminant generation governs air
    changes per hour required
  • density of contaminant governs position of fans
  • density gt1 (ie solvents) - low level fan in wall
  • density lt1 (ie hot gases) - high level fan in
    roof
  • problems include
  • dead areas where poor airflow allows
    contamination to build up
  • heat losses due to high rate of air change

43
LOCAL EXHAUST VENTILATION (I)
  • Hood or exhaust inlet
  • receptor hood
  • contaminant directed into a large hood by fan
    assisted 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)

44
LOCAL EXHAUST VENTILATION (II)
  • ducting
  • straight with gentle bends and angled joints
  • sufficient air flow to prevent deposition of
    solids
  • access ports for cleaning and flow monitoring
  • filter or purifying system
  • cyclones, washers, electrostatic, bag filters

45
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 outlet
  • careful location to avoid
  • cyclic pollution
  • effects of weather of air disturbance

46
BIOLOGICAL HAZARDS
  • zoonoses
  • animal infections transmitted to persons in the
    course of their work
  • bacilli
  • infections such as Legionnaires or Weils
    disease
  • fungi
  • extrinsic allergic alveolitis
  • blood-borne infections
  • hepatitis B and AIDS

47
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

48
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 protective equipment

49
LEGIONNAIRES DISEASE
  • caused by inhalation of airborne droplets
    containing 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

50
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

51
BLOOD-BORNE INFECTIONS
  • hepatitis B (virus)
  • severe form of jaundice
  • infection through contact with blood or bodily
    fluids
  • persons at risk include health workers and
    emergency services
  • protect through preventing puncture wounds,
    disinfection and disposable gloves
  • AIDS (virus)
  • debility of immune system
  • infection through contact with blood or bodily
    fluids
  • persons at risk include health/social workers and
    emergency services
  • protect through preventing puncture wounds,
    disinfection and disposable gloves

52
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

53
REQUIREMENTS OF COSHH
  • assess the risks to health arising from exposure
  • prevent or adequately control exposure
  • ensure that control measures are used and
    properly maintained
  • monitor exposure and carry out appropriate health
    surveillance
  • ensure that employees are properly informed,
    trained and supervised

54
COSHH ASSESSMENT (I)
  • which hazardous substances are present?
  • brought into the workplace
  • dusts, fumes, leakages
  • finished products or wastes
  • who might be exposed?
  • employees
  • contractors
  • public

55
COSHH ASSESSMENT (II)
  • do they represent a significant risk?
  • hazardous properties (toxic, corrosive, irritant)
  • quantity used and frequency of use
  • possible routes of exposure (inhalation, contact)
  • possibility of exposure exceeding OEL
  • possibility of leakage, spillage or release
  • cleaning and maintenance operations

56
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

57
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

58
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 and exposure could be significant

59
RECORDING AND REVIEWING THE ASSESMENT
  • record enough information
  • to show how decisions on risks and precautions
    were made
  • to clearly show the responsibilities for
    implementing the precautions
  • review the assessment
  • at no less than 5-yearly intervals
  • whenever it is thought that the assessment might
    not be valid
  • where there has been a significant change in the
    work

60
INFORMATION, INSTRUCTION AND TRAINING
  • inform, instruct and train employees about
  • the nature of the substances and the risks
    arising from exposure
  • the precautions that should be taken
  • give information and instruction on
  • the purpose and use of control measures
  • use of personal protective equipment
  • results of any monitoring or health surveillance
  • emergency procedures

61
DISPOSAL OF HAZARDOUS SUBSTANCES (I)
  • Safe Storage
  • segregate
  • control storage to prevent risks to employees and
    others
  • keep hazardous and non-hazardous waste separate
  • ensure correct labelling
  • keep quantities to a minimum
  • separate incompatible hazardous wastes

62
DISPOSAL OF HAZARDOUS SUBSTANCES (II)
  • Transport
  • use correct type of vehicle
  • inspect load prior to transport to check
  • description of material
  • containment
  • labelling
  • documentation
  • transfer waste only to an authorised person
  • transfer must be accompanied by written
    documentation
  • identification
  • quantity
  • time and place of transfer
  • details of current and intended holder
  • special waste requires use of a consignment note
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