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Feeling the heat for slideshare

  1. 1. Feeling the Heat – Managing Risks from Heat Stress at Work Mike Slater (President Elect)
  2. 2. Human beings create heat
  3. 3. 100 Watts 200 Watts 800 Watts
  4. 4. 100 Watts 200 Watts 800 Watts The more physically demanding our activity, the more heat we’re producing
  5. 5. We have to lose heat to the environment – but not too much
  6. 6. But we can gain heat from to the environment too
  7. 7. Radiation Convection
  8. 8. Evaporation Radiation Convection
  9. 9. Heat stroke Heat exhaustion Heat syncope Heat cramps Prickly heat
  10. 10. Heat stroke Heat exhaustion Heat syncope Heat cramps Prickly heat
  11. 11. Source: WHO
  12. 12. Heat stroke Heat exhaustion Heat syncope Heat cramps Prickly heat
  13. 13. Evaporation Radiation Convection
  14. 14. Air temperature Humidity Mean radiant temperature Air velocity These are the environmentl factors we have to consider when assessing the risk of heat stress
  15. 15. Air temperature Humidity Clothing Mean radiant temperature Metabolic rate Air velocity
  16. 16. Air temperature Clothing Mean radiant temperature Acclimatisation Humidity Metabolic rate Air velocity And there are other factors we need to consider
  17. 17. Air Temperature Standard thermometer
  18. 18. Humidity
  19. 19. Radiant heat Globe thermometer
  20. 20. Air Velocity
  21. 21. Metabolic rate 1 Met = 58 Wm-2
  22. 22. Clothing 1 Clo = Insulation value of 0,155 m2 oC/W
  23. 23. Acclimatisation YES ? OR NO?
  24. 24. Air movement Humidity Work rate Mean radiant temp. Air temp. Clothing Heat stress index Acclimn
  25. 25. A Structured Approach to Heat Stress Risk Assessment Identify Hazards Assess Risk using screening methods WBGT Index Identify Controls Expert analysis PHS Index Expert analysis Physiological measures
  26. 26. A Structured Approach to Heat Stress Risk Assessment Identify Hazards Assess Risk using screening methods WBGT Index Identify Controls Expert analysis PHS Index Expert analysis Physiological measures
  27. 27. A Structured Approach to Heat Stress Risk Assessment Identify Hazards Assess Risk using screening methods WBGT Index Identify Controls Expert analysis PHS Index Expert analysis Physiological measures
  28. 28. Screening methods Talking to people Observations Checklists
  29. 29. This looks complicated, but we can probably identify the risk factors fairly easily
  30. 30. A Structured Approach to Heat Stress Risk Assessment Identify Hazards Assess Risk using screening methods WBGT Index Identify Controls Expert analysis PHS Index Expert analysis Physiological measures
  31. 31. WBGT Index Indoors WBGT = 0.7 tnwb + 0.3 tg Outdoors WBGT = 0.7 tnwb + 0.2 tg + 0.1 ta
  32. 32. ACGIH TLVs for Heat Stress Allocation of work in work Light cycle Moderate Heavy 75% to 100% 31.0 28.0 - 50% to 75% 25% to 50% 0 to 25% 29.0 30.0 31.5 27.5 29.0 30.5 31.0 32.0 32.5 Workload V ery heavy 28.0 30.0
  33. 33. A Structured Approach to Heat Stress Risk Assessment Identify Hazards Assess Risk using screening methods WBGT Index Identify Controls Expert analysis PHS Index Expert analysis Physiological measures
  34. 34. A Structured Approach to Heat Stress Risk Assessment Identify Hazards Assess Risk using screening methods WBGT Index Identify Controls Expert analysis PHS Index Expert analysis Physiological measures
  35. 35. Physiological assessment Temperature Heart rate
  36. 36. Miner’s Core Temperature & Heart Rate Source: OHTA.
  37. 37. The risks here are more complex – an expert evaluation is likely to be needed
  38. 38. A Structured Approach to Heat Stress Risk Assessment Identify Hazards Assess Risk using screening methods WBGT Index Identify Controls Expert analysis PHS Index Expert analysis Physiological measures
  39. 39. Hierarchy of Control Prevention Engineering Working Practices Personal Protection
  40. 40. Hierarchy of Control Prevention Engineering Working Practices Personal Protection Let’s look at some examples of typical controls
  41. 41. Insulation of hot surfaces to reduce radiant and convective heat www.lubisol.com
  42. 42. Extracting hot air
  43. 43. Blowing in cool air http://mikegigi.com
  44. 44. Providing protective clothing
  45. 45. Regular drinks of water
  46. 46. Management Measures Screening & health surveillance Information, instruction, training Supervision Self regulation Provide water
  47. 47. Hierarchy of Control Supervision Prevention Maintenance Auditing Engineering Working Practices Personal Protection Water Health surveillance Monitoring Information Training
  48. 48. Further Information
  49. 49. http://www.hse.gov.uk/temperature/thermal/index.htm
  50. 50. http://www.bohs.org/resources/res.aspx/Resource/filename/840/TG12.pdf http://www.bohs.org/resources/res.aspx/Resource/filename/1473/04_TG12_Addendum_to_2nd_Edition.pdf
  51. 51. President-elect@bohs.org www.bohs.org Twitter: @bohsworld www.slideshare.net/mikeslater

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