TLVs for heat stress

Mike Slater

Threshold Limit Values ® (TLVs)for heat stress are included inthe American Conference ofGovernmental IndustrialHygienists (ACGIH) TLV booklet

TLVs® are guidelines designedfor use by occupationalhygienists in making decisionsregarding safe levels ofexposure to various chemicalsubstances and physical agentsfound in the workplace.

This flowchart summarises howto apply the TLV’s. However. It’squite complex. We’ll go through it step by step

General approach Detailed Heat Strain Screening Analysis Monitoring

Heat Stress NO STOPexpected? YESSCREENING

Screening NO Clothing adjustment factors available? YES

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

Screening NO Clothing adjustment factors available? YES If no clothing adjustment factors are available, go straight to heat strain (physiological) monitoring

Screening NO Clothing adjustment factors available? YES This may be necessary, for example, where chemical protective suits are being worn

Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Limit exceeded? YES

Work out the WBGT from theresults of environmentalmeasurements and apply theclothing corrections

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

Compare the corrected WBGTwith the Action Limit Values

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

To use this table you have to know• the time spent working and resting• the metabolic rate

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

So, for a job involving moderatework where 75% of the time is spentworking and 25% resting

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

Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Low Risk Limit exceeded? YES

Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES

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

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

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

General Information, instruction & trainingcontrols Regular drinks of water Self regulation Health screening and surveillance Encourage reporting symptoms Encourage healthy lifestyles Monitoring

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

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

Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit exceeded? YES

The Action Limit referred tohere is that associated with theindex being used NOT theACGIH Action Limit

Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit exceeded? YES

Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Low Risk exceeded? YES

Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Continue work Low Risk exceeded? Monitor YES

Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Continue work Low Risk exceeded? Monitor YES NO TLV exceeded? YES

The TLV referred to here is thelimit value associated with theindex being used NOT theACGIH Screening TLVs

Detailed analysis NO Are data available for detailed analysis? YES NO Action Limit Continue work Low Risk exceeded? Monitor YES NO TLV exceeded? YES

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

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

Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES What if the TLV is exceeded?

Heat strain monitoring NO Implement Continue work TLV exceeded? general Maintain controls controls Monitor YES Perform heat strain (physiological) monitoring

Physiological assessment Core Temperature Heart rate

Personal Monitor

Miner’s Core Temperature & Heart Rate Source: OHTA.

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

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

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

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

Job-specific controls Engineering controls Administrative controls Personal protective equipment

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

 At workstation  Ta = 24 0C  Tw = 22 0C  Tg = 28 0C  V = 0.4 m/sWork involves monitoring processMinimal manual effort requiredStandard overalls worn

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

 At workstation  Ta = 24 0C  Tw = 22 0C  Tg = 28 0C  V = 0.4 m/sWBGT = 23.8 0C

Metabolic rate categoriesCategory Metabolic Rate (W)Rest 115Light 180Moderate 300Heavy 415Very Heavy 520

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

Screening NO Clothing adjustment factors available? YES Are screening NO criteria for Action Low Risk Limit exceeded? YES

Screening NO Clothing adjustment factors available? YES Are screening NO Continue work criteria for Action Low Risk Monitor Limit exceeded? YES

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

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

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

Screening NO Clothing adjustment factors available? YES Are screening criteria for Action Limit exceeded? YES Are screening NO criteria for TLV exceeded? YES

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

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

Reduce risk Allow boiler to cool down before starting work

Working methods Mechanical aids Self pacing

Manage exposure time Implement work:rest regime Work restricted to 25% to 50% of work cycle

Provide information, instructionand training Risks Good working practice Symptoms to look out for

Provide water Drink at regular intervals

Health surveillance Pre-placement medical screening Regular health checks Encourage reporting of symptoms

Encourage healthy lifestyle Diet Exercise Moderate alcohol consumption

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

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

Furnace Repair Air Wet bulb Globe Air temp. temp. temp. velocity (0C) (0C) (0C) (m/s) 98 45 150 1 WBGT = 76.5 0C

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

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

Screening NO Clothing adjustment factors available? YES Are screening criteria for Action Limit exceeded? YES Are screening NO criteria for TLV exceeded? YES

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

Are screening criteria for TLV exceeded? YES NO Are data available for detailed analysis? YESPerform heat strain (physiological) Detailed analysis monitoring

http://www.slideshare.net/mikeslatermike@diamondenv.co.ukhttp://diamondenv.wordpress.comTwitter: @diamondenvMike Slater

Mike Slater, Diamond Environmental Ltd. (mike@diamondenv.co.uk) This presentation is distributed under the Creative Commons Attribution-NonCommercial-ShareAlike UK:International Licence

http://diamondenv.wordpress.com	833
http://www.diamondenv.co.uk	582
http://translate.googleusercontent.com	8
http://ranksit.com	2
http://pinterest.com	1

TLVs for heat stress

by Mike Slater

Accessibility

Categories

Upload Details

Usage Rights

5 Embeds 1,426

Statistics

TLVs for heat stress Presentation Transcript