TLVs for heat stress

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Overview of the ACGIH Threshold Limit Values for heat stress. Includes some worked examples

TLVs for heat stress

  1. 1. Mike Slater
  2. 2. Threshold Limit Values ® (TLVs)for heat stress are included inthe American Conference ofGovernmental IndustrialHygienists (ACGIH) TLV booklet
  3. 3. TLVs® are guidelines designedfor use by occupationalhygienists in making decisionsregarding safe levels ofexposure to various chemicalsubstances and physical agentsfound in the workplace.
  4. 4. This flowchart summarises howto apply the TLV’s. However. It’squite complex. We’ll go through it step by step
  5. 5. General approach Detailed Heat Strain Screening Analysis Monitoring
  6. 6. General approach Detailed Heat Strain Screening Analysis Monitoring
  7. 7. Heat Stress NO STOPexpected? YESSCREENING
  8. 8. Screening NO Clothing adjustment factors available? YES
  9. 9. TLV Clothing CorrectionsClothing Type WBGT CorrectionWork clothes (long sleeve and pants) 0Cloth (woven material) coveralls 0Double layer woven clothing 3SMS polypropylene coveralls 0.5Polyolefin overalls 1Limited use vapour-barrier overalls 11
  10. 10. Screening NO Clothing adjustment factors available? YES If no clothing adjustment factors are available, go straight to heat strain (physiological) monitoring
  11. 11. Screening NO Clothing adjustment factors available? YES This may be necessary, for example, where chemical protective suits are being worn
  12. 12. TLV Clothing CorrectionsClothing Type WBGT CorrectionWork clothes (long sleeve and pants) 0Cloth (woven material) coveralls 0Double layer woven clothing 3SMS polypropylene coveralls 0.5Polyolefin overalls 1Limited use vapour-barrier overalls 11
  13. 13. Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Limit exceeded? YES
  14. 14. Work out the WBGT from theresults of environmentalmeasurements and apply theclothing corrections
  15. 15. WBGT Index No direct exposure to sunlight WBGT = 0.7 tnwb + 0.3 tg With direct exposure to sunlight WBGT = 0.7 tnwb + 0.2 tg + 0.1 ta
  16. 16. Compare the corrected WBGTwith the Action Limit Values
  17. 17. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  18. 18. To use this table you have to know• the time spent working and resting• the metabolic rate
  19. 19. Metabolic rate categoriesCategory Metabolic Examples Rate (W) SittingRest 115 Sitting or standingLight 180 Light hand / arm work WalkingModerate 300 Moderate lifting Heavy materials handlingHeavy 415 Pick and shovel workVery Heavy 520
  20. 20. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  21. 21. So, for a job involving moderatework where 75% of the time is spentworking and 25% resting
  22. 22. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  23. 23. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  24. 24. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  25. 25. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  26. 26. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0If the adjusted WBGT is below this value the Action Limit is not exceeded
  27. 27. Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Low Risk Limit exceeded? YES
  28. 28. Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES
  29. 29. Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES NO If the Action Limit is Are screening exceeded then the WBGT criteria for TLV exceeded? value is compared with the TLV criteria YES
  30. 30. ACGIH TLVs – Screening TLVAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 31.0 28.0 - -50% to 75% 31.0 29.0 27.5 -25% to 50% 32.0 30.0 29.0 28.00 to 25% 32.5 31.5 30.5 30.0
  31. 31. Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES Are screening NO Implement criteria for TLV general exceeded? controls YES
  32. 32. General Information, instruction & trainingcontrols Regular drinks of water Self regulation Health screening and surveillance Encourage reporting symptoms Encourage healthy lifestyles Monitoring
  33. 33. Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES Are screening NO Implement Continue work criteria for TLV general Maintain controls exceeded? controls Monitor YES
  34. 34. Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES Are screening NO Implement Continue work criteria for TLV general Maintain controls exceeded? controls Monitor YES
  35. 35. Detailed analysis NO Are data available for detailed analysis? YES If the TLV is exceeded, consider carrying out a more detailed analysis using a more sophisticated method, such as the Predicted Heat Strain (PHS) index
  36. 36. Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit exceeded? YES
  37. 37. The Action Limit referred tohere is that associated with theindex being used NOT theACGIH Action Limit
  38. 38. Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit exceeded? YES
  39. 39. Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Low Risk exceeded? YES
  40. 40. Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Continue work Low Risk exceeded? Monitor YES
  41. 41. Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Continue work Low Risk exceeded? Monitor YES NO TLV exceeded? YES
  42. 42. The TLV referred to here is thelimit value associated with theindex being used NOT theACGIH Screening TLVs
  43. 43. Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Continue work Low Risk exceeded? Monitor YES NO TLV exceeded? YES
  44. 44. Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Continue work Low Risk exceeded? Monitor YES NO Implement TLV exceeded? general controls YES
  45. 45. Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Continue work Low Risk exceeded? Monitor YES NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES
  46. 46. Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES What if the TLV is exceeded?
  47. 47. Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES Perform heat strain (physiological) monitoring
  48. 48. Physiological assessment Core Temperature Heart rate
  49. 49. Personal Monitor
  50. 50. Miner’s Core Temperature & Heart Rate Source: OHTA.
  51. 51. Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES Perform heat strain (physiological) monitoring Excessive heat NO strain based on monitoring? YES
  52. 52. Guidelines for limiting Heat StrainFactor Work should be discontinued if:Heart rate (beats per minute) Greater than 180 minus age in yearsCore temperature Greater than 38.5 0C (acclimatised) Greater than 38.0 0C (unacclimatised)Recovery heart rate 120(beats per minute) (at one minute after peak work)Other Symptoms of sudden and severe fatigue, nausea, dizziness or lightheadedness
  53. 53. Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES Perform heat strain (physiological) monitoring Excessive heat NO strain based on monitoring? YES
  54. 54. Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES Perform heat strain (physiological) monitoring Excessive heat NO strain based on monitoring? YES Implement Job- specific controls
  55. 55. Job-specific controls Engineering controls Administrative controls Personal protective equipment
  56. 56. Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES Perform heat strain (physiological) monitoring Excessive heat NO strain based on monitoring? YES Implement Job- specific controls
  57. 57. Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES Perform heat strain (physiological) monitoring Excessive heat NO strain based on monitoring? YES Implement Job- specific controls
  58. 58.  At workstation  Ta = 24 0C  Tw = 22 0C  Tg = 28 0C  V = 0.4 m/sWork involves monitoring processMinimal manual effort requiredStandard overalls worn
  59. 59. WBGT Index No direct exposure to sunlight WBGT = 0.7 tnwb + 0.3 tg With direct exposure to sunlight WBGT = 0.7 tnwb + 0.2 tg + 0.1 ta
  60. 60.  At workstation  Ta = 24 0C  Tw = 22 0C  Tg = 28 0C  V = 0.4 m/sWBGT = 23.8 0C
  61. 61. Screening NO Clothing adjustment factors available? YES
  62. 62. TLV Clothing CorrectionsClothing Type WBGT CorrectionWork clothes (long sleeve and pants) 0Cloth (woven material) coveralls 0Double layer woven clothing 3SMS polypropylene coveralls 0.5Polyolefin overalls 1Limited use vapour-barrier overalls 11
  63. 63. Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Limit exceeded? YES
  64. 64. Metabolic rate categoriesCategory Metabolic Rate (W)Rest 115Light 180Moderate 300Heavy 415Very Heavy 520
  65. 65. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  66. 66. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0 WBGT = 23.8 0C
  67. 67. Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Low Risk Limit exceeded? YES
  68. 68. Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES
  69. 69. Boiler Cleaning Air Wet Globe Air temp. bulb temp. velocity (0C) temp. (0C) (m/s) (0C) Start of work 34 19 51 0.2 After 5 hours 32.5 18.5 51.5 0.2 Heavy manual effort required Standard overalls worn
  70. 70. Boiler Cleaning Air Wet Globe Air temp. bulb temp. velocity (0C) temp. (0C) (m/s) (0C) Start of work 34 19 51 0.2 After 5 hours 32.5 18.5 51.5 0.2 WBGT = 28.6 0C
  71. 71. Screening NO Clothing adjustment factors available? YES
  72. 72. TLV Clothing CorrectionsClothing Type WBGT CorrectionWork clothes (long sleeve and pants) 0Cloth (woven material) coveralls 0Double layer woven clothing 3SMS polypropylene coveralls 0.5Polyolefin overalls 1Limited use vapour-barrier overalls 11
  73. 73. Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Limit exceeded? YES
  74. 74. Metabolic rate categoriesCategory Metabolic Rate (W)Rest 115Light 180Moderate 300Heavy 415Very Heavy 520
  75. 75. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  76. 76. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  77. 77. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0 WBGT = 28.6 0C So Action Limit is exceeded
  78. 78. Screening NO Clothing adjustment factors available? YES Are screening criteria for Action Limit exceeded? YES Are screening NO criteria for TLV exceeded? YES
  79. 79. ACGIH TLVs – Screening TLVAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 31.0 28.0 - -50% to 75% 31.0 29.0 27.5 -25% to 50% 32.0 30.0 29.0 28.00 to 25% 32.5 31.5 30.5 30.0
  80. 80. ACGIH TLVs – Screening TLVAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 31.0 28.0 - -50% to 75% 31.0 29.0 27.5 -25% to 50% 32.0 30.0 29.0 28.00 to 25% 32.5 31.5 30.5 30.0 WBGT = 28.6 0C So TLV is NOT exceeded provided work is restricted to 50% of shift
  81. 81. Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES Are screening NO Implement criteria for TLV general exceeded? controls YES
  82. 82. Reduce risk Allow boiler to cool down before starting work
  83. 83. Working methods Mechanical aids Self pacing
  84. 84. Manage exposure time Implement work:rest regime Work restricted to 25% to 50% of work cycle
  85. 85. Provide information, instructionand training Risks Good working practice Symptoms to look out for
  86. 86. Provide water Drink at regular intervals
  87. 87. Health surveillance Pre-placement medical screening Regular health checks Encourage reporting of symptoms
  88. 88. Encourage healthy lifestyle Diet Exercise Moderate alcohol consumption
  89. 89. Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES Are screening NO Implement Continue work criteria for TLV general Maintain controls exceeded? controls Monitor YES
  90. 90. Furnace Repair Air Wet bulb Globe Air temp. temp. temp. velocity (0C) (0C) (0C) (m/s) 98 45 150 1 Heavy manual effort required Thick, woollen clothing worn
  91. 91. Furnace Repair Air Wet bulb Globe Air temp. temp. temp. velocity (0C) (0C) (0C) (m/s) 98 45 150 1 WBGT = 76.5 0C
  92. 92. TLV Clothing CorrectionsClothing Type WBGT CorrectionWork clothes (long sleeve and pants) 0Cloth (woven material) coveralls 0Double layer woven clothing 3SMS polypropylene coveralls 0.5Polyolefin overalls 1Limited use vapour-barrier overalls 11
  93. 93. TLV Clothing CorrectionsClothing Type WBGT CorrectionWork clothes (long sleeve and pants) 0Cloth (woven material) coveralls 0Double layer woven clothing 3SMS polypropylene coveralls 0.5Polyolefin overalls 1Limited use vapour-barrier overalls 11
  94. 94. Furnace Repair Air Wet bulb Globe Air temp. temp. temp. velocity (0C) (0C) (0C) (m/s) 98 45 150 1 Corrected WBGT = 79.5 0C
  95. 95. Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Limit exceeded? YES
  96. 96. Metabolic rate categoriesCategory Metabolic Rate (W)Rest 115Light 180Moderate 300Heavy 415Very Heavy 520
  97. 97. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0
  98. 98. ACGIH TLVs – Action LimitAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 28.0 25.0 - -50% to 75% 28.5 26.0 24.0 -25% to 50% 29.5 27.0 25.5 24.50 to 25% 30.0 29.0 28.0 27.0 Corrected WBGT = 79.5 0C So Action Limit is exceeded
  99. 99. Screening NO Clothing adjustment factors available? YES Are screening criteria for Action Limit exceeded? YES Are screening NO criteria for TLV exceeded? YES
  100. 100. ACGIH TLVs – Screening TLVAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 31.0 28.0 - -50% to 75% 31.0 29.0 27.5 -25% to 50% 32.0 30.0 29.0 28.00 to 25% 32.5 31.5 30.5 30.0
  101. 101. ACGIH TLVs – Screening TLVAllocation of Workloadwork in work Light Moderate Heavy V erycycle heavy75% to 100% 31.0 28.0 - -50% to 75% 31.0 29.0 27.5 -25% to 50% 32.0 30.0 29.0 28.00 to 25% 32.5 31.5 30.5 30.0 Corrected WBGT = 79.5 0C So TLV is exceeded
  102. 102. Are screening criteria for TLV exceeded? YES NO Are data available for detailed analysis? YESPerform heat strain (physiological) Detailed analysis monitoring
  103. 103. http://www.slideshare.net/mikeslatermike@diamondenv.co.ukhttp://diamondenv.wordpress.comTwitter: @diamondenvMike Slater
  104. 104. Mike Slater, Diamond Environmental Ltd. (mike@diamondenv.co.uk) This presentation is distributed under the Creative Commons Attribution-NonCommercial-ShareAlike UK:International Licence

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