1. PHYSIOLOGICAL RESPONSES OF UNDERGROUND COAL MINERS UNDER INIMICAL WORKING ENVIRONMENT Delivered By ~ Dr. Netai Chandra Dey PROFESSOR(MINING) BENGAL ENGINEERING AND SCIENCE UNIVERSITY, SHIBPUR, HOWRAH

2.  Reasons to take up Ergo based research work  Objectives of the study  Unit operations in UG mine  Provision of ergonomic study in DGMS circular  Selection of subject for the study  Physical characteristics of Roof Bolters  Threshold limit values of different environmental parameters  An overview on physiological status w.r.t some strain indices  Time element of roof bolting activity in spell and shift  Determination of work load as per various scientific classification  Adequacy of job duration in mines  Possible R & D initiatives  Conclusion and recommendations Lecture Content

3. WHY ERGONOMICS-BASED RESEARCH WORK IN MINING IS IMPORTANT?  Huge base of workers constituting more than 80% of total work force in mining industry.  Huge absenteeism about 30-35%.  Significant report of sufferings from MSD’s and postural problems, which indicates poor health of miners.  Considerable compensation is being paid to the miner by private and public enterprises.  Poor OMS of underground miners which is around 0.5-0.6 since last 10-15 years, indicates poor efficiency of UG miners.  Mine reserve sustainability in India for at least next 100 years

4. OBJECTIVES OF THIS PARTICULAR STUDY  Determination of workload of selective category of miners  Optimization of job duration of different mining operation with respect to given environmental inputs.  Determination of workload of selective category of miners  Optimization of job duration of different mining operation with respect to given environmental inputs.

5. 471 no. of mines 163 open cast 308 underground Executive: 15,431 Supervisor: 36,855 Workmen: 3,28,359 (86%) Total: 3,80,645 MANPOWER OF CIL Open cast Under ground MANPOWER OF SCCL Executive: 2477 Supervisor: 14,568 Workmen: 49,041 (74.3%) Total: 66,086

6. As per DGMS Circular & X th conference on safety in mines held in New Delhi during 26-27 Nov.2007 following ergonomic study have been made mandatory: 1.Assessment of work processes 2.Assessment of posture 3.Assessment of tools/aids 4.Cardio- vascular assessment 5.Vibration studies of machines as per ISO As per DGMS Circular & X th conference on safety in mines held in New Delhi during 26-27 Nov.2007 following ergonomic study have been made mandatory: 1.Assessment of work processes 2.Assessment of posture 3.Assessment of tools/aids 4.Cardio- vascular assessment 5.Vibration studies of machines as per ISO PROVISION OF ERGONOMIC STUDY IN DGMS CIRCULAR

7. How ergonomics can help industry Work load determination and adequacy of workload to an Individual. Work optimization can be done through changing environmental parameters. Work station designing. Designing of HEMM’s and other machine operator’s seating, cabin etc. Handling of heavy tools. Postural study to minimize musculo-skeletal disorder(MSD) related troubles. Work load determination and adequacy of workload to an Individual. Work optimization can be done through changing environmental parameters. Work station designing. Designing of HEMM’s and other machine operator’s seating, cabin etc. Handling of heavy tools. Postural study to minimize musculo-skeletal disorder(MSD) related troubles.

8. STEPS INVOLVED IN THE CONVENTIONAL UNDER GROUND DEVELOPMENT DISTRICT Clear the face(balance coal)to make the face ready for drilling Drill holes Charging the holes & blast taking due safety Dress the face Support gang to erect supports as per approved SSR Updating ventilation Spray at face before & after blasting(90m from face) Shovelling and carrying of coal to load onto tubs Prepare faces for the next round of blasting

9. Priority based criteria that have been used to select the different mining operations for the present study are as follows: Priority based criteria that have been used to select the different mining operations for the present study are as follows: 1.Activities that are quantitative in nature. 2. Activities where the miners have to devote a significant time at a stretch in the allocated working area. 3. Activities that are supposed to be relatively physically demanding under adverse conditions of mines. 1.Activities that are quantitative in nature. 2. Activities where the miners have to devote a significant time at a stretch in the allocated working area. 3. Activities that are supposed to be relatively physically demanding under adverse conditions of mines.

10. PHYSICAL PARAMETERS OF ROOF BOLTERS (MEAN±SD, RANGE) CATEGORY OF WORKER UNIT NO. OF SUBJECT HT.(CM)WT.(KG)BSA(M²)BMI(KG/ M²) ROOF BOLTERS MINE A5 160.3±3.33 (156.5-162.5) 61.67±7.64 (55-70) 1.64±0.06 (1.58-1.7) 21.4±4.04 (20.8-28.6) MINE B5 158.75±0.35 (158.5-159) 49.5±13.44 (40-59) 1.48±0.1 (1.36-1.6) 19.6±5.23 (15.9-23.3) CategoryBMI range (kg/m²) Severly underweight<16.5 Underweight16.5-18.5 Normal18.5-25 Over weight25-30 Obese classes>30 Stages of human BSA values (Acceptable limits) For men1.9 m² For women1.6 m² REFERENCE: 1.Adapted from US EPA 1985 2.WHO recommended body weight based BMI values for adults.

11. PHYSIOLOGICAL PARAMETERS (DIRECT & DERIVED) IN ROOF BOLTING FOR TWO DIFFERENT MINE PARAMETERMine A (n=5)Mine B (n=5) WHR(bpm)123.8±3.77(120-130))109.8±3.77(105-115) RCC (%)54.08±4.80(48.11-61.45)52.18±4.75(47.11-60.45) NCC(bpm.)53.2±3.34(51-59)28.2±3.34(22-30) OT( 0 F)99.2+0.4(98.4-99.8)99.3+0.4(98.6-100.2)  It is observed that roof bolters experience the highest responses in both spells except net cardiac cost.  Mean WHR for both group gets elevated around 70-75% compared to their resting responses. Both the elevation is statistically significant.

12. PERCENTAGE OF ROOF BOLTING WORK EXCEEDING THE RECOMMENDED LIMITS OF PHYSICAL STRAIN INDICESACCEPTED LIMITSMine AMine B WHR(bpm)11010060 LCW35 beats over resting pulse100 RCC (%)30%10080 NCC(bpm)3010060  The average work load of individual roof bolter of two different mine during their bolting activity is judged against various recommended indices of cardiac strain.  It is seen that in mine A 100% of bolters remain above 30% level of RCC whereas 80% of mine B remains above 30% RCC.  WHR of mine A is 100% beyond the limit whereas in mine B it is 60%. The same effect is observed in case of NCC.

13. Parameter Reference Classification of workload LightModerateHeavy Very heavy Extremely heavy Roof Bolting Driller (n=5) Remarks Working Heart rate (bpm) Astrand<9090-110111-130131-150151-170*123.8 Roof Bolters are in heavy category. Energy expenditure (Kcal) Ramanathan, et al 1.0-2.52.6-4.04.1-6.06.1-8.0>8*4.15 Roof Bolters are in heavy category. Net cardiac cost (bpm) Chamoux, et al ≤20 20-3031-4041-5051-60 *53.2 Roof Bolters are in very heavy category. Physiological workload classification & comparison with observed values(Mine-A) * Mean values are given

14. Parameter Reference Classification of workload LightModerateHeavy Very heavy Extremely heavy Roof Bolting Driller (n=5) Remarks Working Heart rate (bpm) Astrand<9090-110111-130131-150151-170*109.8 Roof Bolters are in moderate category. Energy expenditure (Kcal) Ramanathan, et al 1.0-2.52.6-4.04.1-6.06.1-8.0>8*3.75 Roof Bolters are in moderate category. Net cardiac cost (bpm) Chamoux, et al ≤20 20-3031-4041-5051-60 *28.2 Roof Bolters are in moderate category. Physiological work load classification comparison with observed values(Mine B) * Mean values are given

15. A glimpse of heart rate at different states of mine A Roof Bolter 28% 71%

16. A comparison of cardiac indices & energy expenditure of Roof Bolters

17. Mean±SD Roof Bolter (n=5) P1P1 P2P2 P3P3 (Range) 112.6±5.74 (98-118) 98.8±5.24 (90-104) 90.6±5.17 (82-97) Recovery heart rate pattern of Subjects (Mine A) Mean ±SD Roof Bolter (n=5) P1P2P3 (Range) 99.2±6.83 (95-106) 87.6±5.50 (82-98) 82±5.41 (78-86) Recovery heart rate pattern of Subjects (Mine B) Brouha’s fatigue assessment techniques ConditionCriteria Normal stateP 1 - P 3 ≥ 10 bpm and P 1, P 2, P 3 ≤ 90 bpm No – recovery stateP 1 - P 3 90 bpm Inverse recovery stateP 3 > 90 bpm and P 1 - P 3 ≤ -10 bpm No increasing cardiac strainP 1 ≤ 110 bpm and P 1 - P 3 > 10 bpm

18. BOLTER (Mine A)TIME(MIN)NUMBER work duration per shift101.12±2.43(99.4-102.84)- spells per shift-4 spell duration per shift25±0.06(25-26.99)*- % time spent by different job elements in an activity of a spell walking with machine & accessories - 5.61 Considering 5 effective hours in a shift roof checking - 5.98 drilling in roof - 21.52 Soaking, pushing of cement cartridge and insertion of bolt - 12.6 Tightening of bolt nut - 2.5 BOLTER (Mine B)TIME(MIN)NUMBER work duration per shift63.8±2.6(61.4-65.3)- spells per shift-3 spell duration per shift21±0.12(20.2-23.4)*- % time spent by different job elements in an activity of a spell walking with machine & accessories - 3.2 Considering 5 effective hours in a shift roof checking - 4.34 drilling in roof - 12.4 Soaking, pushing of cement cartridge and insertion of bolt - 6.8 Tightening of bolt nut - 1.6

19. UNDERGROUND MINE ENVIRONMENT PARAMETERS (Mine A) PARAMETERSDB(°c)WB(°c)NWB(°c) AIR VELOCITY (m/min) WBGT(°c)HUMIDITY (%)ET(°c) MEAN±SD (RANGE) 28.84±0.72 (28-30.5) 27.74±0.68 (27-29.5) 28.23±0.71 (27-30) 4.92±4.65 (1-18) 28.41±0.69 (27.3-30.3) 92.07±1.68 (89-98) 29±0.35 (28-29.5) Classification of environmental zone at various level of ET ClassificationET( 0 C)Observed value( 0 C) Very hot zone>30 29* Hot zone28.33-29.94 Warm zone26.67-28.28 Comfortable zone21.11-26.61 *Values are given °C, ET & WBGT Permissible Heat Exposure Threshold Limit Values: - (By ACGIH) Work Rest Regimen Light Moderate Heavy Continuous work 30.0 26.7 25.0 75% of work; 25% of rest, each Hr. 30.6 28.0 25.9 50% of work; 50% of rest, each Hr. 31.4 29.4 27.9 25% of work; 75% of rest, each Hr. 32.2 31.1 30.0 Observed WBGT values 28.41*

20. UNDERGROUND MINE ENVIRONMENT PARAMETERS (Mine B) PARAMETERSDB(°c)WB(°c)NWB(°c) AIR VELOCITY (m/min) WBGT(°c)HUMIDITY (%)ET(°c) MEAN±SD (RANGE) 31.5± 0.96 (28.5-33.5) 29.9±0.94 (26.5-31.5) 29±1.02 (27-32) 22.2 ± 0.12 (12.6-42.6) 27.8 ± 1.06 (26.5 -31.5) 88 ±3.5 (75-93) 27.95 ±0.35 (26.5-31.5) ClassificationET( 0 C)Observed Value( 0 C) Very hot zone>30 27.95* Hot zone28.33-29.94 Warm zone26.67-28.28 Comfortable zone21.11-26.61 Classification of environmental zone at various level of ET Permissible Heat Exposure Threshold Limit Values: - (By ACGIH) Work Rest Regimen Light Moderate Heavy Continuous work 30.0 26.7 25.0 75% of work; 25% of rest, each Hr. 30.6 28.0 25.9 50% of work; 50% of rest, each Hr. 31.4 29.4 27.9 25% of work; 75% of rest, each Hr. 32.2 31.1 30.0 *Values are given °C, ET & WBGT Observed WBGT values 27.8*

21. Category of work Actual work (in each hour) Mine A Recommended work (in each hour) Mine A Actual work (in each hour) Mine B Recommended work (in each hour) Mine B Roof Bolter20.22Min.*15 Min.12.76 Min.45 Min. * Effective time in a shift is considered to be 5 hrs.  In Mine A the roof bolters are doing more work (though this may not be adequate) than the recommended work limit. Hostile Environment is responsible.  In Mine B the roof bolters are doing much less work than the recommended work limit.  The hostile environment of Mine A is responsible for increased job demand and hence the bolters are in heavy work load category. So, the mine unit is deprived of effective utilization of system inputs whereas, the humanizing environment of Mine B helps to reduce the job demand to moderate category.  The roof bolters of mine B are heavily under loaded and the jobs should be increased accordingly.  The environment of Mine A should be monitored and improved adequately so that their work limits can be enhanced appropriately.  In Mine A the roof bolters are doing more work (though this may not be adequate) than the recommended work limit. Hostile Environment is responsible.  In Mine B the roof bolters are doing much less work than the recommended work limit.  The hostile environment of Mine A is responsible for increased job demand and hence the bolters are in heavy work load category. So, the mine unit is deprived of effective utilization of system inputs whereas, the humanizing environment of Mine B helps to reduce the job demand to moderate category.  The roof bolters of mine B are heavily under loaded and the jobs should be increased accordingly.  The environment of Mine A should be monitored and improved adequately so that their work limits can be enhanced appropriately. Job duration optimization of Roof Bolters in Mines

22. Possible R&D initiatives required in mining field Workstation designing in under ground and open cast. Ergonomical designing of HEMM’s operators cabin Postural study regarding operators reach/ control with respect to HEMM’s Determination of workload and adequate work rest regimen for miners in different working conditions and work environment. Nutritional study Delay in onset of fatigueness to maximize worker’s efficiency in mines

23. CONCLUSION & RECOMMENDATIONS  Decreases Injury Frequency so that the compensation made towards the employee is drastically reduced.  Increases production and productivity  Ergonomic study helps to scheduling and optimizing the work bouts to reach the companies objective comfortably.  Decreases Absenteeism.  Increases Health and Comfort which will have direct impact on the work efficiency of employee.  Decreases Injury Frequency so that the compensation made towards the employee is drastically reduced.  Increases production and productivity  Ergonomic study helps to scheduling and optimizing the work bouts to reach the companies objective comfortably.  Decreases Absenteeism.  Increases Health and Comfort which will have direct impact on the work efficiency of employee.

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