Element 8: Hazardous Substances

Question 1

State physical forms of chemical agents which may exist in work place

Answer 1

• Dust.
• Fibres.
• Fumes.
• Gases.
• Mists.
• Vapours.
• Liquids.

Question 2

Identify five main health hazard classifications of chemicals.

Answer 2

THINK ITCH C.
•Toxic
• Harmful
• Irritant
• Corrosive
• Carcinogenic

Question 3

Define the characteristics of mist and fumes, identify a potential source of each in construction activities.

Answer 3

Mists - Small liquid droplets suspended in air. e.g. Paint sprayed.

Fumes - Fine solid particles created by condensation of vapour. e.g. emitted from welding processes.

Question 4

Distinguish briefly between acute & chronic I’ll health effects.

Answer 4

Acute - where quantity of toxic or harmful substance absorbed into body produces very quick harmful effects. I.e. seconds, minutes or hours.

Chronic - Harmful effects of substance absorbed takes very long time to appear. Months or years.

Question 5

Identify routes of entry of chemicals into the body.

Answer 5

THINK AIII

• Absorption
• Inhalation
• Ingestion
• Injection

Question 6

What is difference between inhalable substance and a respirable substance?

Answer 6

Inhalable - Enter mouth, nose & upper respiratory tract.

Respirable - Deeper penetration of lung itself (7-8 microns or less)

Question 7

What information is generally provided on product label of a substance that is classified dangerously for supply.

Answer 7

• Name, Address & Tel.
• Quantity
• product identifiers (EC, CAS or inventory no.)
• Hazard pictograms.
• Signal word.
• Hazard statements.
• Precautionary statements.
• Supplementary info

Question 8

What is purpose of safety data sheet?

Answer 8

Provide sufficient info about hazards of substance or prep of them to take appropriate steps to ensure H&S in workplace in all aspects of use. Incl. handling, transport & disposal.

Question 9

What is difference between passive & active sampling devices?

Answer 9

Passive - air sample passes through device natural air currents, diffuses into chamber absorbent material removed for analysis.

Active - Air forced through instrument by pump.

Question 10

Give limitations in use of stain tube detectors.

Answer 10

• Provide spot sample one moment rather than average reading.
• Accuracy +/- 25%.
• Correct no of strokes must be used; losing count or too many gives inaccurate results.
• Volume air inaccurate (incorrect assembly/ operation leaks etc)
• Cross sensitivity
• Problems caused by temp & pressure variations.
• Deterioration
• Variation of reagent make up between tubes.

Question 11

What are smoke tubes used for?

Answer 11

To test effectiveness of ventilation or air conditioning systems & chimneys, to detect leaks in industrial equipment, to assess air pressures & provide info on air movements in a work area.

Question 12

What is Guidance note EH40?

Answer 12

Sets out workplace exposure limits for substances hazardous to health.

Question 13

What is workplace exposure limit (WEL)?

Answer 13

Max concentration of airborne substance averaged over period to which employees exposed to inhalation under any circumstances.

Question 14

What do you understand by the term “time weighted average” in relation to a WEL. Under COSHH regs?

Answer 14

Measurements taken over a particular time period (15 mins short or 8hrs for long term limits) then averaged out.
Concept of time weighted averages allows exposures to exceed limit provided equivalent exposures below compensate.

Question 15

Give 3 examples of limitations of WEL’s

Answer 15

• Take no account of human sensitivity & susceptibility
• Cannot be applied directly to working periods exceed 8 hrs.
• Designed only to control absorption into body following inhalation.

Question 16

What two reference periods are commonly used with TWAs? (Time weighted averages)

Answer 16

• 15 mins (STEL’s)
• 8 hrs (LTEL’s)

Question 17

What principles of control are illustrated by the following measures?
A) Using granulated pottery glazes instead of powder.
B) Vacuum cleaning rather than sweeping with a broom.
C) Job rotation.
D) Using water based adhesives rather than solvent based ones.

Answer 17

(A) Substitution
(B) Works process change
(C) Reducing time exposure
(D) Sunbstitution

Question 18

What is difference between local exhaust ventilation & dilution ventilation?

Answer 18

LEV control measure removing contaminants generated at source.

Dilution ventilation deals with contamination in general atmosphere of workplace area.

Question 19

What are dead areas, & why are they a problem for dilution ventilation?

Answer 19

Areas that remain dormant where air is not changed due to air flow pattern from positioning of extractor fans.

Question 20

List 4 main types of respirator & 3 main types breathing apparatus.

Answer 20

• Filtering Facepiece.
• Half mask/ori nasal.
• Full face.
• Powered visor respirators.

• Fresh air hoses
• Compressed airlines
• Self contained systems

Question 21

What are key criteria in selection of appropriate respirator to use?

Answer 21

• Concentration of contaminant & its hazardous nature (harmful toxic)
• physical form (vapour, dust)
• Level of protection offered by RPE
• Presence or absence of normal oxygen concentrations.
• Duration worn.
• Compatibility with other PPE
• Shape of users face & influences on fit.
• Facial Hair interferes with effective seal.
• Physical requirements of job. Move freely.
• Physical fitness of wearer.

Question 22

What is main purpose of routine health surveillance?

Answer 22

To identify as early as possible any variations in health of employees which may be related to working conditions.

Question 23

Identify 6 chemical & 4 biological agents commonly encountered in construction activities.

Answer 23

1) lead
2) silva
3) cement dust
4) asbestos
5) Carbon dioxide
6) Carbon Monoxide

1) Blood borne viruses
2) Weils disease leptospirosis.
3) legionnaires- legionellosis
4) Hepatitis.

Question 24

Identify two asphyxiant gases & outline their I’ll health effects.

Answer 24

Carbon dioxide & carbon monoxide.

Do not cause direct injury to respiratory tract but reduce oxygen available to body.

Question 25

Identify 3 sources of organic solvents used in construction. Describe their ill health effects.

Answer 25

• Paints
• Varnishes
• Paint remover

Cause irritation & inflammation of skin, eyes & lungs, causing dermatitis, burns, breathing difficulties incl occupational asthma & sensitisation. Vapours given off usually flammable & may be narcotic progressively causing drowsiness, nausea & unconsciousness
Some organic solvents are carcinogenic

Question 26

Identify the controls used to avoid or reduce exposure to cement dust & wet cement.

Answer 26

• Eliminating or reducing exposure.
• Use of work clothing & PPE such as gloves, dust masks & eye protection.
• Removal of contaminated clothing.
• Good hygiene & washing on skin contact.
• Health surveillance of skin condition to control chrome burns & dermatitis.

Question 27

Identify 3 main types of asbestos

Answer 27

• Chrysotile (White).
• Crocidolite (Blue).
• Amosite (Brown).

Question 28

What are 3 air monitoring sampling methods for asbestos & when should they be carried out?

Answer 28

By trained staff
• Compliance sampling - within action limits)
• Background sampling - before starting work
• Clearance sampling- after removal & cleaning area.

Question 29

A duty of care is placed on persons who generate, import, handle, transport & dispose of controlled waste. What responsibilities does that duty of care place on such persons?

Answer 29

• Manage waste legally
• Ensure does not escape control
• Transfer waste only to authorised person
• Adequately describe waste.
• Provide adequate documentation

Question 30

Name 6 factors to consider when handling and storing waste for disposal.

Answer 30

1) Hazardous nature of waste.
2) Manual handling risks
3) Segregation of waste prevents cross contamination.
4) Compactors moving parts guarded
5) Collection vehicles hazards reversing manoeuvring
6) Documentation.

Question 31

What steps are to be taken if discover asbestos on site?

Answer 31

• Stop work immediately.
• prevent anyone entering area.
• contain - Seal area
• Warning signs “possible asbestos contamination”
• Inform Site Supervisor immediately
• Contaminated clothing decontaminated & disposed of as hazardous waste.
• Undress shower wash hair put on clean clothing
• Contact specialist surveyor or AR contractor.