B4 Flashcards
Jan 20 (a) see Jul 10 Jan 09 Jan 08 Jan 06 below
Employees in a large manufacturing organisation are exposed to a solvent by inhalation, throughout their 8- hour shift
a)
(i) Use the WEL data in the table below to calculate the 8-hour time-weighted average (TWA) exposure to a solvent for an employee. Your answer should include the detail of calculation to show your understanding of how the exposure is determined. (7)
(a)
(ii) The organisation decides to change the working patterns so that each employee does a single task for a 12-hour shift. An employee is assigned to the task of charging the mixers for their 12-hour shift. Within the shift, they are allowed two 45-minute breaks where their exposure is assumed to be zero.
Using this information and the relevant data above, calculate the 8-hour TWA exposure for this employee. (2)
(iii) Outline the legal implications of this change in the working pattern. (2)
(b) The occupational health department at the organisation needs to decide whether to carry out health surveillance for employees exposed to this solvent.
(i) Outline the purposes of health surveillance. (4)
(ii) Suggest ONE type of health surveillance that may be appropriate for the employees using this solvent. (1)
(iii) Other than health surveillance, identify FOUR functions that may be carried out by an occupational
Employees in a large manufacturing organisation are exposed to a solvent by inhalation, throughout their 8- hour shift health service in a large manufacturing organisation. (4)
ai) The TWA exposure is the sum of the (exposure for each period multiplied by time(hrs)) then divided by 8
(140x2. 5) + (0x0.25) + (100x2) + (0x1) + (25x2) + (0x0.25) = 600/8 = 75ppm
ii(100x10.5)+(0x1.5) = 1050+0/8= 131ppm.
(iii)
The change in the mode of working has increased the individual’s exposure so it is now in excess of the WEL;
The employer is no longer complying with the principle of adequate control under the COSHH Regulations and must introduce additional controls.
(bi)Purposes of health surveillance include:
- To ensure that a worker is fit to work with a specific hazard such as exposure to dust in a bakery
- Identifying early signs of health problems amongst employees so that better controls can be put in place
- To fulfil a statutory duty required by certain pieces of legislation e.g. noise, vibration, radiation
- Provides opportunity for employees to raise concerns about how work affects their health
- Provides an opportunity to reinforce training about health-related risks that are present in the workplace
(ii)
Lung function test (spirometry)
(iii)
Functions that may be carried out by an occupational health service include:
• Pre-employment screening(Fit – Physical, mentally);
• Return to work rehabilitation (After a work-related illness or injury);
• Counselling(listening ear for stress);
• First aid treatment
• Dental treatment
• Maintaining health records for employees
• Liaising with enforcement authorities
Risk assessment – (DSE for admin, Ergonomic for warehouse
Jul 19 See Jan 11 Jan 08
Outline how an occupational hygienist should determine an employee’s long term personal exposure to total inhalable hazardous dust. (10)
Personal exposure to total inhalable dust should be carried out by:
Monitoring throughout an 8 hour shift;
Keeping a record of activities involved;
Noting the time / duration of sampling; use an approved gravimetric method - MDHS 14/3;
Calibrated pump (2.2l/min;
Sample head (IOM / 7 hole / conical);
Filter (pre-weighed); sample head in breathing zone (within 30cm - eg lapel); pump air through filter at Specified flow rate for specified time period (8 hour?);
Check flow calibration; collect filter / cartridge and send to be weighed (calibrated scales / approved / accredited laboratory);
Calculate weight gain and determine volume of air drawn through pump during sampling period; calculate concentration of dust in air (weight gain / volume = milligrams of dust per cubic metre of air = mg/m3)
Jan 19 Jul 11 Jul 08 Jan 07
(a) Give the meaning of the term biological monitoring. (2)
(b) Outline the circumstances in which biological monitoring may be appropriate. (4)
(c) Outline the practical difficulties that an employer must take into account when introducing a programme of biological monitoring. (4)
a) Biological monitoring is the measurement / assessment of hazardous substances or their metabolites in tissues, secretions, excreta or expired air and is complementary to air monitoring. (2)
(b) BM is appropriate:
• where required by law - CLAW Reg Lead exposures - blood / urine lead levels monitored; COSHH / EH40 - BMGVs Carbon monoxide 30 ppm carbon monoxide in end-tidal breath - Post shift; Chromium VI 10 μmol chromium/mol creatinine in urine - Post shift; Isocyanate 1 μmol urinary diamine/mol creatinine in urine - Post task; Lindane 35 nmol/L (10 μg/L) of lindane in whole blood (= 70 nmol/L of lindane in plasma) – Random
- where there is a risk of significant absorption through non-respiratory routes - esp. skin
- where there is significant reliance on RPE
- where there is a valid technique for measuring exposure / body burden
- in order to evaluate the effectiveness of existing control measures
- where there is a specified BMGV
- as part of a health surveillance programme
- where there is a need for information on accumulated dose
(c) Practical difficulties include:
gaining informed consent - dealing with objections / concerns / fears - ethical / phobias / suspicion etc; expensive / time consuming - staffing problems / cover (post-shift / task / random); requires specialist (medical) expertise; requires special facilities - hygiene etc; maintaining sample integrity - avoiding cross-contamination / cross-infection; maintaining personal records over long periods - 40 / 50 years / confidentiality issues; dealing with “over-exposed” persons - change of duties / suspension / counselling
Jul 18
In a chemical process employees are exposed to two organic liquids. Table 1 below shows the average personal exposure levels to each of the organic liquids for one employee measured over an 8-hour day.
(a) Using the information in Table 1, demonstrate that the 8-hour time-weighted average (TWA) exposures of the employee to BOTH Liquid A and Liquid B are as shown in Table 2. (8)
Your answer should include detailed working to show how the exposure is calculated.
The workplace exposure limits (WELs) for the two liquids are as follows:
(b) Outline what actions the employer might need to take to control exposure to Liquid A, which is an essential component of the chemical process. (7)
(c) Comment on the exposure to Liquid B. (1)
(d) There is a concern that exposure to a mixture of these two liquids might increase the risk to employees. Consider why this might be a valid concern. (4)
Use the WEL table for working out the TWA exposures
a
Liquid A
(280x0.5) + (110x1) + 150x2) + (150x3) / 8
= 140 + 110 + 300 + 450 / 8 = 125ppm
Liquid B
(140x0.5) + (80x1) + (50x2) + (50x3) / 8
= 70 + 80 + 100 + 150 / 8 = 50ppm
b
Continue to monitor current controls for all the processes with exposure;
• Exposure when measuring out the liquid is actually above the WEL so further controls should
be considered:
o Installing an LEV
o full enclosure of the process;
o RPE with appropriate filters for the chemical;
o Job rotation to reduce daily exposure of a single employee;
• Supervising of mixing could be done from a further distance or via video link;
c
Exposure to liquid B is well below the WEL at one quarter, therefore considered adequately controlled at all times;
d
• Synergistic effects could occur in this chemical process - the risk of exposure to the mixture is greater than the sum of the risks from exposure to the individual liquids;
• the effects of exposure to liquids A and B were independent or additive;
Jul 17
Information relating to the solvent Butan-2-one in the Health and Safety Executive (HSE) document EH40, is as follows:
(a) Identify what BMGV stands for. (1)
(b) Give the meaning of the term ‘workplace exposure limit’ (WEL). (2)
(c) Outline why Butan-2-one has been assigned BOTH a WEL and a BMGV in EH40. (4)
(d) Outline legal differences between a WEL and a BMGV. (3)
WEL table PPM x Time
(a) ‘Biological Monitoring Guidance Value’
(b) WEL is Max concentration of an airborne substance, averaged over a reference period, to which employees may be exposed by inhalation.
(c) Butan-2-ol has the potential to be inhaled and therefore it has been assigned a WEL and it can also be absorbed through the skin so it is assigned the ‘Sk’ notation. Simply controlling exposure via one of these possible routes of entry will not be sufficient to adequately control the overall risks of exposure.
(d) exceeding the WEL is a breach the Control of Substances Hazardous to Health Regulations 2002 whereas the BMGV is only guidance.
Jan 17
Hardwood dust generated during sanding can be inhaled. The dust has been analysed to determine the particle size and the results are shown in the bar graph below:
a) Outline the possible effects on health from exposure to hardwood dust. (5)
(b) Describe the likely distribution of the hardwood dust in the respiratory tract of the employees and the mechanisms the body may use to defend itself following inhalation of the hardwood dust. (14)
(c) Identify a type of health surveillance for employees exposed to hardwood dust. (1)
(a) Effects include from exposure to hardwood dust can include: • Allergic respiratory effects • Bronchitis • Coughing • Sneezing • Shortness of breath • Asthma • Rhinitis • Skin disorders such as dermatitis • Nasal cancer
(b)
• The 60% hardwood dust with particle size 11 – 100 would enter the nasal cavity where cilary hairs would filter the dust. Mucus would also be secreted and form snot – removed by sneezing, coughing or picking;
• The 35% hardwood dust with particle size 7- 10 would be removed by the mucociliary escalator. Particles are trapped by ciliary hairs in the thoracic region where they are coated with mucous. The product is gradually pushed up the escalator during exhalation and finally removed from the respiratory tract by spitting (expectoration);
• The 5% hardwood dust with particle size of less than 7 would penetrate down into the gas exchange region of the lungs (alveoli). Here macrophages would deal with the particles using phagocytosis. These special white blood cells would engulf the particles, secrete enzymes and then cleaned out of the blood by the liver and kidneys.
• If the dust cannot be digested, the defence mechanism fails because the phagocytes die and causes scarring of lung tissue.
Body mechanisms include:
• Nasal hair, mucous, sneeze reflex, ciliary escalator and, in the lungs themselves,
• The inflammatory response is also a defence mechanism
• Nasal hair to catch particles and prevent entry
• Sneezing and coughing reflexes to expel the dust from the body
• Production of mucus to stop entry by use of the mucocilliary escalator
• Dust that reaches the sacs and the lower part of the airways where there are no cilia is
attacked by special cells called macrophages. Besides macrophages, the lungs have another system for the removal of dust. The lungs can react to the presence of germ-bearing particles by producing certain proteins. These proteins attach to particles to neutralize them.
(c) Lung function test and possibly inspection of skin for signs of dermatitis & questionnaire about breathing
Jul 16 Jan 12 Jan 09
It is often necessary to monitor an employee’s personal exposure to hazardous substances. Some of the measurement principles that can be used include gravimetric analysis, microscopy and chemical analysis.
For EACH of these measurement principles:
(a) Identify a type of hazardous substance for which it can be used AND suggest a typical workplace situation where such a measurement may be necessary. (6)
(b) Outline the type of equipment and the methodology used to determine the employee’s personal exposure to the hazardous substance. (14)
(a)
Gravimetric
• Used for measuring total inhalable or respirable dusts;
• in a woodworking workshop cut wood for flat pack furniture;
Microscopy
• Used for the measurement of fibres;
• Following the accidental disturbance or planned removal of asbestos materials;
Chemical analysis
• Used in the measurement of gases, vapours and fumes in workplaces;
• Laboratories or those involved in the manufacture of chemicals;
b
Gravimetric
• a filter attached to a pump is used.
• There are three main types of sample head depending on the type of dust being determined.
• These are the multi-orifice (7 hole) sampler, the IOM and the cyclone head.
• The filter is weighed before and after sampling;
• The concentration is determined from the weight gain and the volume of air used;
• Expressed in mg/m3.
Microscopy
• a membrane fitted on an appropriate sampling head such as a cowl is attached to a pump;
• After sampling is completed, a phase contrast microscope is used to count the fibres;
• The number of fibres in a known proportion of the sample is calculated and extrapolated to
the whole sample;
• The result being expressed as fibres per millilitre of air (f/ml).
Chemical analysis
• a tube or sampling head with a filter impregnated with an adsorbing material such as charcoal is attached to a pump;
• After sampling it is desorbed and analysed in a laboratory;
• An analysis techniques which can identify both the chemical and its concentration is gas
chromatography;
• Concentrations are expressed in parts per million or milligrams/m3.
General points
• calibrate the pumps before use;
• draw a known volume of air through the filter or tube;
• a number of samples should be taken to minimise errors in measurement;
• Ensure the sampling head was placed in the breathing zone;
• Use the appropriate methods for determining the hazardous substances (MDHS).
Jan 14
An organisation operates a chemical manufacturing process that uses different grades of the same powder. The table below shows data for the two different grades of powder. Employees handle both powders during manufacturing process and are therefore likely to inhale the powders.
Product
Product. Description Part size dist(mics)
Powder grade 1 White powder. 7-20
Powder grade 2 White powder 1-5
(a) For each powder
(i) describe the likely distribution of the powder in the respiratory tract of the employees (4)
(ii) describe the mechanisms that the body may use to defend itself from inhalation of the powder (6)
(b) Outline how an occupational hygienist would determine the employees’ long-term personal exposure to the dust in powder grade 2. (10)
(a) (i)
Distribution
POWDER GRADE 1
• Inhalable dust;
• Particles above 10 microns will enter in the nasal cavity;
• Particles between 7 and 10 will enter the trachea, bronchi and bronchioles;
POWDER GRADE 2
• Respirable dust;
• Particles size of 1-5 it is likely to enter the gas exchange region of the lungs, the alveoli;
(a) (ii) Defence mechanisms
Powder grade 1
• Particles above 10 micros will be filtered by ciliary hairs, mucous will also form snot and this will be sneezed out;
• Hairs in the mucociliary escalator will waft the particles up during exhalation, they will then be coughed or spat out;
Powder grade 2
• Phagocytosis – macrophages will engulf the particles, secrete enzymes to break them down and dispose via the kidneys;
Also…
• Inflammatory response;
• Scarring or fibrosis.
Jul 13 Jan 12 Jul 10 Jan 08
Methanol (an organic solvent) is being used in the production of a specialist coating.
An operative’s measurement of exposure to methanol varies throughout their 8-hour working day. The results of measurement of the operative’s exposure are as follows:
Task undertaken by operative Measuring out and adding methanol Adding other components to the mix Supervision of mixing and decanting Cleaning equipment using solvents Duration of task 15 minutes 2 hours 3 hours Exposure to methanol (ppm) 280 90 150 150 Assume exposure is zero at all other times.
(a) Calculate the 8 hour TWA exposure to methanol for the operative. Your answer should include detailed working. (8)
(b) Information relating to methanol in EH40 Workplace Exposure Limits is as follows: Table 2 Substance Methanol CAS No. 67-56-1
Workplace Exposure Limit Comments
Long-term exposure limit (8 hour TWA limit reference period)
200 ppm
266mg/m3
Short-term exposure limit (15 minute reference period)
250 ppm
333 mg/m3
Sk
Using your results from part (a), the original exposure information in Table 1 and by selecting the relevant data from Table 2, explain what actions might be required by the employer in order to comply with the COSHH regulations 2002. (8)
(c) Outline how the personal exposure of the operative to methanol can be measured. (4)
(a) (280x 0.25) + (90x2) + (150x2) + (150x3) + (0x0.75) = 70+180+300+450+0 = 125 ppm 88
(b)
• The long-term exposure did not exceed the workplace exposure limit (WEL) and consequently the existing control measures could continue to be applied and monitored on a regular basis.
• The short-term exposure during measuring out and adding the methanol does exceed the WEL by 30 ppm and consequently the employer would need to introduce further control measures for these operations,
including;
o substituting a less hazardous solvent for the methanol;
o introducing automation for the dispensing and charging of the solvent;
o installing local exhaust ventilation or improving the standard of that already fitted; o providing the operative with respiratory protective equipment to reduce inhalation; o ensuring that they wore gloves to protect from splashes since methanol could be absorbed through the skin.
- In order to comply with the COSHH Regulations, there may be a need to carry out a measurement of the exposure to other components involved in the process and to compare the results with the WELs quoted in EH40, investigating any synergistic or additive effects;
- Further measurements may also have to be undertaken to determine if the STEL is exceeded at any time during the completion of the other described tasks;
- a system of on-going monitoring would have to be introduced to determine the effectiveness of the additional control measures that had been introduced.
c
• The use of a sample tube packed with sorbent material (activated charcoal) fixed by means of a clip-on collar in the breathing zone;
• A known volume of air would be drawn across the tube by means of a pump and the methanol absorbed onto the sorbent material;
• The methanol could then be desorbed in a laboratory by the use of thermal desorption and analysed using gas chromatography;
• A number of samples would have to be taken to increase accuracy.
Jan 11 Jul 08
Five employees work an 8 hour shift during which they are exposed to a hazardous dust. The employer has asked an occupational hygienist to undertake monitoring of the employees’ personal exposure to the hazardous dust.
(a) Describe how the hygienist should determine the employees’ long term personal exposure to the total inhalable hazardous dust. (10)
(b) The five employees were each monitored for exposure to total inhalable dust during the same 8 hour shift. Four of the results are roughly equivalent but the fifth is significantly higher. Outline the possible reasons for this apparent discrepancy. (10)
(a) Personal exposure to total inhalable dust should be carried out by
:• monitor the exposure throughout the eight-hour shift;
• note the work undertaken during the monitoring;
• note the time for which the sampling was undertaken;
• A gravimetric method should be used incorporating a pump, a filter and an appropriate
sampling head such as a 7 hole, an IOM or a conical inhalable head with the head being
positioned in the breathing zone of the employee;
• The pump flow rate would be calibrated and noted as would the volume of air in the sample
collected;
• Weigh the filter before and after the sampling to determine any gain in the weight;
• The concentration of total inhalable dust could then be calculated by dividing the weight gain
by the volume of air with the result being expressed in mg/m3.
b
• local exhaust ventilation provided is not working effectively in all areas;
• Errors in the calibration of the pump flow;
• Errors in the timing of the air measurement;
• Errors in the selection of the filter;
• Errors in weighing the filter – misreading or uncalibrated scales;
• The individual could have been involved in the dustier operations;
• They could have taken fewer or shorter breaks than the other operators;
• They could have not taken sufficient care with personal hygiene;
• They could have continued to wear dusty overalls for long periods;
• Deliberate sabotage.
Jul 10 Jan 09 Jan 08 Jan 06
(a) Use the data below to calculate the 8-hour Time-Weighted Average (TWA) exposure to a solvent for a factory worker. Your answer should include detailed workings of the calculation. (7)
Working period (total shift time = 8 hours)
Period. Task. Exposure ppm
08.00 –10.30 Weighing ingredients 140
10.30 – 10.45 Break 0
10.45 – 12.45. Charging Mixers 100
12.45 – 13.45. Lunch 0
13.45 – 15.45. Cleaning Equip 25
15.45 – 16.00. Assisting Maint Staff 0
Tasks undertaken by worker
(b) Explain THREE of the “principles of good practice” that should be considered when deciding if the control of exposure can be treated as “adequate” under the COSHH regulations (3)
(a) (140x2.5) + (0x0.25) + (100x2) + (0x1) + (25x2) + (0x0.25) = 600/8 = 75ppm
(b) COSHH principles of good practice include requirements to:
Design and operate processes and activities to minimise emission release of substances hazardous to health
Take into account all relevant routes of exposure inhalation, skin absorption, ingestion when developing control measures
Control exposures by measures that are proportionate of the health risks
Periodically check and review control measures to ensure their continuing effectiveness;
Identify occasions when personal protective equipment may have to be used alongside other control measures;
Provide information and training to employees;
avoid increasing the overall risk to health and safety by the introduction of selected control measures.
Jul 09
In a manufacturing process, operators use a range of solvents.
Describe a monitoring strategy that could be used to measure the exposure of the operators to solvent vapours. (10)
The exposure of workers should be assessed in accordance with any procedures set out in the relevant
MDHS. A 3 stage monitoring strategy should be adopted (see “Monitoring strategies for toxic substances”
HSG 173):
(1) initial appraisal;
(2) basic survey;
(3) detailed survey
initial appraisal
• the objective of determining if and to what extent more detailed monitoring of employees’ exposure would be required;
• It is basically an exercise to gather information on matters such as;
• the activity being carried out;
• the substances in use;
• the duration of exposure;
• relevant exposure limits
• the nature and use of any existing controls.
• the use of qualitative methods such as dust lamps or smoke tubes;
Basic Survey
• appropriate if there had been major changes in the processes, substances used, control levels and exposure standards since the last survey had been carried out.
• Semi-qualitative methods such as stain tubes could be used though it might be necessary to use more complex equipment such as photo ionisation detectors and portable gas chromatography.
Detailed Survey
• Used in circumstances where carcinogens, mutagens or respiratory sensitisers are present;
• when previous basic surveys found exposure to be close to WEL;
• during high risk commissioning or maintenance activities;
• when there was a need to justify the costs of additional control measures;
• more detailed information gathering would be required on work practices, maintenance procedures, the results of previous monitoring and the suitability of the personal protective equipment currently in use;
• greater emphasis on personal sampling over longer periods of time and the taking of a greater number of samples over a wider range of conditions;
• More sophisticated sampling methods and equipment such as those reliant on laboratory analysis would be used and these might include biological monitoring.
Jul 08
(a) Outline the meaning of the phrase `adequate control’ as used in the Control of Substances
Hazardous to Health Regulations (COSHH), so far as it relates to exposure by inhalation. (4)
(b) Describe the approach that is followed when setting a workplace exposure limit (WEL) for a hazardous substance used in the workplace. (8)
(c) The data below for three different products is taken from a supplier’s catalogue. Using the data outline the likely extent and effects of exposure when handling EACH of these products. (8)
Prod/ Chem name/formulaConcentration/Physical Form
C1 Sodium Hydroxide NaOH 99.9%. Pellets
C2 Sodium Hydroxide NaOH 97% Powder
C3 Sodium Hydroxide (NaOH) 50% in water. Liquid
(a) Adequate control = Principles of Good Practice in Schedule 2A COSHH 2002 (as amended) are
applied – ie plant & equipment designed to minimise release;
all routes of entry considered; control measures adequate / proportionate and effectiveness regularly reviewed;
employees given appropriate instruction, information & training in hazards, risk and protective measures required;
any WEL not exceeded; exposure ALARP for carcinogen / mutagen / asthmagen; where no WEL then in-house standards should be applied.
(b)
• WELs are set on the recommendation of the Advisory Committee on Toxic Substances (ACTS);
• following on assessment undertaken by the Working Group on the Assessment of Toxic Chemicals (WATCH) of toxicological, epidemiological and other data;
• If a no observed adverse effect level (NOAEL) is found, this is used as the starting point in setting a WEL;
• If actual levels of exposure achievable in a workplace setting are below NOAEL, then the WEL is set at this lower level;
• In the absence of NOAEL, the WEL is set at a level that represents good occupational hygiene practice determined by the likely severity of the health hazard and the cost and effectiveness of controls;
• Wherever possible, the WEL is not set at a level where there is positive evidence of adverse effects on human health;
(c) All 3 chemicals contain NaOH which is caustic and corrosive, with the potential to cause burns - skin / eye / respiratory irritation and burns. Concentrations vary so in theory higher concentrations are more hazardous - however, the physical form influences the likelihood of exposure:
C1 = pellets can cause burns if accidentally ingested (poor personal hygiene) or on contact with skin when handling but less likely to be inhaled or enter eyes - although this is a possibility as there will be some dust from the pellets;
C2 is a powder - more easily becomes airborne and therefore more readily inhaled and dust blown into eyes - powders / fine dusts more likely to enter gloves etc unnoticed;
C3 is a liquid - lower concentration but higher risk of splashes to skin, face, eyes and body
Jul 08
Personal dust monitoring has been carried out on five employees, all of whom work in the same factory area where dust is released. The five employees were sampled at the same time and for equal duration. Four of the results are roughly equivalent but the fifth is significantly higher.
Outline the possible reasons for this apparent discrepancy. (10)
Apparent discrepancy in the fifth result could be associated with
(i) the WORKING ENVIRONMENT - person works in dustier area, different air movement patterns / ventilation, variability in effectiveness of LEV in sampling area;
(ii) the TASKS BEING CARRIED OUT- person does different / dustier tasks to others, uses different equipment or adopts a different work routine / posture / shorter breaks etc;
(iii) the MONITORING EQUIPMENT- defects, false readings, wrong calibration, wrong filter, misreading results, errors in weighing etc;
(iv) the INDIVIDUAL PERIOD - poor hygiene, dusty clothing; sabotage
Jul 07
The following is an entry in the List of Approved Workplace Exposure Limits which can be found in document EH40.
(a) Explain the meaning of the following terms:
(i) Chemical Abstract Services CAS number (2)
(ii) Workplace Exposure Limit (2)
(iii) Long-term Exposure Limit (8 hour TWA reference period) (2) (iv) Biological monitoring guidance value (Bmgv) (2)
(b) Describe the physiological effects of carbon monoxide on the body and identify the symptoms that may be experienced by exposed persons. (6)
(c) Outline the control measures that could be used to reduce exposure to carbon monoxide in a motor vehicle repair premises. (6)
(a)
(i) CAS number = a unique internationally recognised identifying number allocated to a particular chemical so as to avoid confusion with other similarly named substances (similar to ISBN for books)
(ii) WEL = the maximum concentration of an airborne substance to which a person may be exposed by inhalation
(iii) LTEL is the airborne concentration (in mg/m3 or ppm) measured as an 8 hour time-weighted average - representing a working shift
(iv) BMGV
• a measure (in exhaled air, urine or blood) of the concentration of a chemical or metabolite in the body;
• when compared with the standards contained in EH40, can assist in checking the effectiveness of existing controls.
• Non-statute; Guidance only
(b) CO is inhaled into the lungs where it passes into the bloodstream, displaces oxygen and combines with haemoglobin to form carboxy-haemoglobin; as this is a relatively stable chemical combination which is only slowly displaced from the blood stream it reduces the capacity of the blood to carry oxygen to the brain, vital organs and body tissues. Resulting symptoms include fatigue, loss of concentration, disorientation, headaches, nausea, dizziness, breathlessness, collapse and ultimately death.
(c) Exposure to CO in a MVR workshop can be reduced by providing suitable LEV (connected to exhaust system); reducing the duration of engine running tests etc; carrying out work outside; providing natural ventilation of work area / vehicle pits; monitoring airborne CO levels; health surveillance - biological monitoring (exhaled breath); installing CO monitors / alarms; providing relevant training and information; segregating test areas from customer facilities.
