Association between duration of coal dust exposure and respiratory impairment in coal miners of West Bengal, India.

Purpose. The prevalence and severity of respiratory disorders are very high among coal miners as continuous exposure of workers in such an environment leads to accumulation of dust in the lungs. This study was designed to assess the prevalence of lung function impairment and to determine whether there is any correlation between dust exposure duration and lung function indices. Materials. Two hundred and thirty underground coal dust-exposed workers and 130 age-matched non-exposed workers were recruited from an underground mine in West Bengal, India. A spirometry test was performed for lung function and also basic information on personnel's dust exposure, smoking and respiratory morbidity was collected. Student's t test, Pearson's correlation coefficient (r), uncorrected Pearson's χ2 test and Fischer's exact test were performed for statistical analysis. Results. Lung function indices were significantly (p < 0.050) impaired between the exposed (43.91%) and non-exposed (23.85%) groups. In addition, highly significant decrements in the pulmonary volumes of exposed subjects were also noted. Furthermore, a high negative correlation was observed between spirometric results and exposure time in the exposed group compared with the non-exposed group. Conclusion. This study suggested a positive relationship between exposure time and lung function deterioration.

Combined effect of coal dust exposure and smoking on the prevalence of respiratory impairment among coal miners of West Bengal, India.

Accelerating prevalence of coal workers pneumoconiosis is considered as a serious occupational health problem. This cross-sectional study was designed to determine the prevalence of lung function impairment of underground coal miners in West Bengal, India. A total of 230 underground coal dust-exposed subjects and 130 nonexposed subjects were examined for lung function test and also information on sociodemographic characteristics, addiction, respiratory morbidity, personnel protective equipment and dust exposure were collected. Lung function impairment was significantly higher in exposed group than nonexposed group and personnel dust exposure level were exceeded above the NIOSH recommended level. In addition, respiratory ailments were found to be higher in exposed group than the nonexposed group. So, this study has established the need for an advanced understanding of the quantifiable and measurable remedies for protection of lung disorder of coal mine workers.

Maximum aerobic capacity of underground coal miners in India.

Miners fitness test was assessed in terms of determination of maximum aerobic capacity by an indirect method following a standard step test protocol before going down to mine by taking into consideration of heart rates (Telemetric recording) and oxygen consumption of the subjects (Oxylog-II) during exercise at different working rates. Maximal heart rate was derived as 220-age. Coal miners reported a maximum aerobic capacity within a range of 35-38.3 mL/kg/min. It also revealed that oldest miners (50-59 yrs) had a lowest maximal oxygen uptake (34.2 ± 3.38 mL/kg/min) compared to (42.4 ± 2.03 mL/kg/min) compared to (42.4 ± 2.03 mL/kg/min) the youngest group (20-29 yrs). It was found to be negatively correlated with age (r = -0.55 and -0.33 for younger and older groups respectively) and directly associated with the body weight of the subjects (r = 0.57 - 0.68, P ≤ 0.001). Carriers showed maximum cardio respiratory capacity compared to other miners. Indian miners VO(2 max) was found to be lower both compared to their abroad mining counterparts and various other non-mining occupational working groups in India.

Cardiac strain of confectionery worker in relation to heat exposure during regular work shift.

CONTEXT: In India, a wide variety of occupations are performed in adverse indoor working environment. Work physiological studies in these jobs are scanty as compared to investigations done on more arduous outdoor occupations. AIMS AND OBJECTIVES: Physiological strain of workers engaged in sweet making activities was assessed in terms of cardiac strain indices in relation to heat stress. SETTING AND DESIGN: 33 full-time workers from eastern India were compared for cardiac strain profile obtained during summer and winter during their regular work shift. A comparison was also done in between younger (n=12) and older (n=16) subjects. MATERIALS AND METHODS: Working heart rate (WHR) was recorded continuously during work. The pulse deceleration index (PDI) was obtained from recovery heart rate (RHR). Net cardiac cost (NCC) and relative cardiac cost (RCC) were the main indices used to evaluate physical strain. Thermal stress assessed from wet bulb globe temperature (WBGT). STATISTICAL ANALYSIS: Students' t-test and Wilcoxon signed rank paired tests were used for comparing physiological responses. Values were considered significant when P < 0.05. RESULTS: Work load was significantly higher in summer for all workers. RCC of younger workers in winter and summer ranged between 18% and 26%. This was significantly lower as compared to the RCC of older workers which was 27% in winter and 30% in summer. The physiological workload appeared to be moderate in nature. The WBGT index was above the recommended range in summer for both the groups. Older workers showed a no recovery pattern in terms of recovery pulse that indicated toward a cumulative stress which may be attributed to a combined effect of heat and work in summer and extra amount of work performed in winter season. CONCLUSION: The physical workload is aggravated with various ergonomic stressors present in the work place. An ergonomic intervention has been indicated as further scope of this study.

A comparison of cardiac strain among drillers of two different age groups in underground manual coal mines in India.

Cardiac strain was evaluated in terms of working heart rate (WHR), relative cardiac cost (RCC), net cardiac cost (NCC) and other recovery indices among six younger (mean age 34.2 +/- 2.7 yr) and sixteen older (mean age 48.9 +/- 5.4 yr) drillers working in a manual underground coal mine over two spells of work. The mean WHR was within the range of 117-132 beats / min with corresponding mean relative cardiac cost between 44-48% of heart rate reserve for the younger group and 53-55% for their older counterparts. The mean NCC was above 50 beats/min for both age groups. It was seen that the workers surpassed the recommended limits of cardiac strain indices. The intensity of workload indicates the job to be "heavy" to "extremely heavy" in accordance with the heaviness scales based on WHR, NCC and recovery heart rates. Heat stress prevailing in the workplace in terms of effective temperature (ET) and wet bulb globe temperature (WBGT), was above the recommended limits as per the guidelines proposed by WHO and ACGIH. High physiological demands of the job which requires predominate static muscular exertions coupled with high heat stress were found to hinder the recovery process and may prove deleterious particularly for the older workers. Therefore, in the present context, the need of ergonomic interventions for job organization and quick reparation of environmental condition are strongly indicted.

A comparison of physiological strain of carriers in underground manual coal mines in India.

Thirty-nine healthy carriers (23-57 years of age) were investigated in underground manual coal mines in West Bengal, India during two different work spells of a single work shift. We compared physiological strain of workers <40 and > or =40 years of age. For both groups, mean heart rate was 124-133 beats/min, with a mean corresponding relative cardiac cost of 50-66%. Maximum aerobic capacities were estimated indirectly, following a standard step test protocol. Average oxygen consumption was 1.07-1.1 l/min, with an energy expenditure of 5.35-5.5 kcal/min among both age groups. Acceptable levels of physiological strain were well encroached, and older workers faced the maximum burden. The tasks studied were heavy to very heavy in nature. The weight of load carriage at a spontaneously chosen speed and the prevailing environmental conditions merit serious attention. There is extreme need of ergonomic interventions in reducing the postural load and musculoskeletal discomforts in this population.

A comparative study of physiological strain of underground coal miners in India.

Ninety-eight healthy underground coal miners aged between 23-58 years were studied during their activity period. Physiological strain of different category of miners in terms of heart rate was monitored continuously with heart rate monitor that revealed the tasks as heavy to very heavy for them. Oxygen consumption was measured directly by using oxylog-2 machine that corresponded to metabolic costs for different activities ranging from 4.96 kcal/min to 5.47 kcal/min. The mean relative aerobic strain varied from 47.4%-56.8%--depicting acceptable level of physical strain was well encroached by the miners who irrespective of ages and categories showed poor recovery responses. This entails that miners are exerting themselves beyond their capacities where inevitably older workforce face the maximum burden.

A study of the workload of underground trammers in the Ranigang coal field area of West Bengal, India.

Thirty healthy trammers were examined in underground haulage mines during their normal activity. Physiological strain in terms of heart rate (HR) varied between 101.6 and 104.7 beats/min with mean net cardiac cost of 33.06 and 34.06 beats/min for younger and older groups respectively. The average relative cardiac cost was lower for younger subjects than for older ones. Oxygen consumption (VO2) was measured with an Oxylog-II machine (UK); subsequently values were estimated. Maximum aerobic capacity was estimated with an indirect method following a standard step test protocol. The responses revealed that the average VO2 during the activity was 0.75 and 0.8 L/min, which corresponded to energy expenditure (EE) of 3.8 and 3.97 Kcal/min for younger and older subjects respectively. The workload in terms of HR and EE was moderate, whereas the aerobic strain experienced by aged workers was above the acceptable level.

Cardiovascular load assessment of coal mine shovelers in west Bengal, India: a comparison between middle age groups.

Cardiovascular load of underground shovelers was assessed in terms of heart rate changes at work in haulage coalmines. Twenty underground shovelers of two different age groups (those of age 31-39 and those of age 40-49) served as subjects. Working heart rate was significantly higher (p < 0.01) in the older group (138.2 beats/min) than in the younger group (130.4 beats/min). Though the net cardiac cost did not differ significantly between the groups (64.8 beats/min and 69.4 beats/min in younger and older groups, respectively), difference in the relative cardiac cost (54.17% and 64.86% in younger and older groups, respectively) proved to be highly significant (p < 0.001). The heart rate up to the third minute of recovery showed significant differences between the groups (p < 0.01). While analysis of physiological responses indicated that the task was very strenuous irrespective of age, cardiac strain was found to be more excessive in the older subjects if continued. The arduous nature of the working environment in the coalfaces was also reported.

Effect of chronic use of different propulsion systems in wheelchair design on the aerobic capacity of Indian users.

BACKGROUND & OBJECTIVE: The use of wheelchairs (WC) of ergonomically different propulsion mechanisms may influence the cardiorespiratory capacity of the WC user. The purpose of the present investigation was to observe the impact of chronic use of four ergonomically different propulsion systems and age of the WC users on their aerobic capacity. METHODS: The male subjects (n=77), exclusively using hand rim (n=20), arm crank using both arms (n=22), arm crank using one arm (n=17), and arm lever using one arm (n=18) propelled WCs and 20 able-bodied (AB) subjects as the control group participated They performed maximal exercise test in continuous, step-wise incremental workload at a crank rate of 50 rpm on an arm-crank ergometer. The VO(2) and heart rate obtained during 2.45 to 3 min of each test exercise, and VO(2max) and HR(max) were derived respectively. Two-way ANOVA and multiple comparison tests were performed to compare the groups with respect to VO(2max) and HR(max). Age was used as a classificatory variable. RESULTS: The maximal physiological response of the AB subjects was superior to the WC users but the WC user groups did not show any significant differences amongst them. The aerobic capacity decreased with advancement of age and for WC users this is more pronounced. Equations for age predicted VO(2max) and HR(max) were also derived. INTERPRETATION & CONCLUSION: As the WC users used the four distinct propulsion systems, it was anticipated that it would induce variation in the physiological variables of the users. But the results of the study revealed that there was no significant difference. Suggesting that the WC users might have developed certain self-regulatory mechanisms in order to overcome the variation induced by the different propulsion systems.

Wheelchair charity: a useless benevolence in community-based rehabilitation.

PURPOSE: Hand rim-propelled manual wheelchairs (WC) are conventionally distributed to persons with dysfunctioning lower limbs for independent ambulation in community-based rehabilitation. The purpose of the present study was to survey the fate of the donated WCs and the difficulties encountered by the users by identifying the cause of rejection, and to evaluate the performance by assessing physiological strain on the recipients during their routine ambulation using cardiorespiratory parameters. METHODS: Personal interview was arranged for the recipients and they were to answer regarding the fate of the donated WC and the cause of rejection for the recipients who rejected their WC. A simple field test was also administered to the users to evaluate the ambulatory performance using the WC. The energetics of WC propulsion at freely chosen speed was studied. RESULTS: Of the WC, 10.49% were for attendant-dependent ambulation, 57.4% were not used, 14.19% were sold and 7.4% were in regular use and 10.5% in occasional use. Most of the recipients rejected their WC due to pain, fatigue and discomfort and lack of habitat adaptability. The cardiorespiratory response was higher in occasional users than regular users. Locomotive tasks using WC are highly energy demanding and contribute to physiological strain. CONCLUSIONS: Hand rim-propelled manual WC are unsuitable for outdoor ambulation due to low speed and high physiological demand; they are also of little use indoors as they are difficult to maneuver under the environmental conditions and architectural restraints. So, they should not be recommended without proper assessment of the user's activity level and requirements.