^{1}

^{*}

^{1}

^{2}

^{3}

All rights reserved.

This study assessed the reduction in forced vital capacity of lungs of sand stone quarry workers exposed to high respirable suspended particulate concentration. The sand stone quarry workers are engaged in different type of activities like drilling, loading and dressing. These different working places have different concentration of RSPM and these workers are exposed to different concentration of RSPM. It is found that exposure duration and exposure concentrations are main factors responsible to damage respiratory tract of worker. It is also revealed from the study that most of the workers are suffering from silicosis if the exposure duration is more than 15 years.

It is more than likely that man has suffered from occupational diseases over a span of time from hunting to agriculture as a means of feeding himself. After the industrial revolution the occupational diseases have been increased and adequate medical and scientific expertise allowed rapid progress to be made towards logical and scientific understanding. The mining industry is a great cause of occupational diseases. The consequence of an inhaled particle depends on its inherent toxicity, its ability to penetrate the site at which it can exert its effects and the amount retained in the lungs [_{P} is the predicted FVC of lung if person is not exposed to polluted environment that means FVC_{P} is normal value of FVC for a person. If FVC is less than FVC_{P} it indicates damage in the respiratory tract. If FVC is reduced it indicates both obstructive and restrictive respiratory disease. Therefore FVC was taken as the parameter to assess the damage. This study relates the reduction in FVC due to exposure duration and RSPM concentration.

The sand stone quarrying process is done manually and mechanically but the involvement of workers in both the cases is significant. There are three types of workers:

The various steps involved in methodology:

Selection of quarries: Quarries of different areas around Jodhpur were selected.

Selection of Workers: Three types of quarry workers and control population (Workers from same socioeconomic group but not exposed to quarry environment) were selected and these workers were categorized depending upon exposure duration.

Questionnaire: ATS-DLD (American Thoracic Society–Division of Lungs Diseases of National Heart & Lungs Institute of America) questionnaire was modified as per local requirement and prepared in “Hindi” language. The workers were reluctant to disclose information related to personal hygiene.

Measurement of Particulate Concentration: Particulate concentration were measured with “Respirable High Volume Sampler’ (APM-451 Model manufactured by Enviro-tech New Delhi-India)

Measurement of Forced Vital Capacity: Spirometer used for the measurement of FVC was “Spiroweb” manufactured by drc drecare- Hyderabad-India.

Statistical Analysis: Statistical analysis was done to check the significance of exposure duration and particulate concentration on decrease in FVC. It was also done to investigate the significance of the difference between the decrease in FVC of two Population (exposed population and controlled population)

The study was conducted on 476 workers, out of these 455 workers data were recorded and remaining 19 worker’s data were lost owing to file damage in computer. Only 419 data were used for the study purposes and rest was discarded due to various reasons. Only male workers were considered for the study because female worker’s percentage in the stone quarrying industry is negligible. Air particulate samples were collected and Respirable Particulate Matter was collected on 8 × 10-inch glass fibre filters for different activities. Air sampling was carried out at every mine and the average RSPM concentration was calculated for different activities. These activities are designated as loading, dressing and drilling and the workers who perform these works are called labour, dresser and driller respectively. The concentrations of these activities are designated as 1, 2, and 3 for normal quarry environment (i.e. loading), dressing and drilling respectively. The forced vital capacity (FVC) of workers engaged in different type of activities was measured with the help of Spirometer. The predicted value of forced vital capacity (FVCp- it depends upon height, weight and age of human) of each worker was calculated by using ERS -93 Equations. The

The control population was selected from the society of same socioeconomic status but these workers were not exposed to mine environment but they are exposed to normal ambient environment. The effect on respiratory tract is chronic therefore exposure duration was divided in four categories, 0–5 yr., 5–10 yr., 10–15 yr. and >15 yr. and these categories are designated as 1, 2, 3 and 4 respectively. Categories of workers, number of workers in each categories and exposure categories are given in

The reduction in forced vital capacity of lung is calculated and it is designated as IFVC and is given by

(A) Males (>18 years):

(B) Males (<18 years):

The mean values of index IFVC are calculated for various cases and are shown in _{1}_{2}

Where _{0}_{1}_{2}_{1} & _{2} respectively. The regression analysis is done by using the data from _{0}_{1}_{2}_{0}_{1}_{2}_{0}_{1}_{2}

Analysis of variance helps to test whether each of the parameters _{1}_{2}

_{0}_{1}_{2}_{1}: not all _{k}_{k,n−k−1,α} = 8.02

Here _{k,n−k−1,α}

Hence reject H_{0} at _{S} be tested by‘t – test’.

_{0}_{j}_{1}: _{j}

The calculated values for‘t’-statistic for _{1} and _{2} are given in

_{1}) = 6.131

_{2}) = 8.510

The value of t_{n−k−1;α/2} = 2.26.

Here t > _{n−k−1;α/2;} therefore reject _{0}

Hence _{1} ≠ 0 and _{2} ≠ 0

As the estimated b_{0}, b_{1} and b_{2} are:

_{0}

_{1} =0.02526

_{2} =0.04801

The estimated multiple regression equation for IFVC is:

The value of R^{2} is 0.924 which means that about 92 % of variation in the dependent variable Y (IFVC) is due to independent variables _{1}_{2.}

To investigate the significance of the difference between the means of two populations viz. exposed and controlled for IFVC; t-test and Cochran-cox test are applied. The t-test for two independent samples is applied when variances of both the populations (exposed and controlled) are unknown but equal whereas the Cochran-cox test is applied for the same, when the variances of both the populations are unknown and unequal. The choice between t-test and Cochran-cox test depends on whether variances of both the populations are equal or not. That is the equality of variances of both the populations can be tested by F-test (Variance Ratio Test).

For IFVC the values of various test statistics: F, t, and Cochran-cox statistic, for different category of workers and controlled population are given in _{c}, for different cases are given in col. (13).Whereas, if value of F-statistic is insignificant then t-statistics for different cases, are calculated and its values are given in col. (9). Significant values of these statistics are marked with *. The critical values for F and Cochran-cox tests are given in cols. (7) and (12). The critical value of‘t’ i.e. _{n1 + n2}

It is observed from the

Noting further that the mean values of concerning index for exposed population is considerably higher than the corresponding value of control population. Therefore, it indicates that forced vital capacity of lungs of stone quarry workers are reduced due to the particulate pollution in quarries.

The study was carried out to find the effect of particulate concentration on forced vital capacity of lungs of stone quarry workers. The results indicates that as the exposure duration increases the forced vital capacity of lungs decreases and the same times if exposure duration is same but concentration of particulate matter increases then again the forced vital capacity of lungs decreases. Therefore the decrease in the forced vital capacity of lungs depends upon the exposure duration and particulate concentration. The equation developed for the decrease in forced vital capacity of lungs of stone quarry workers is given as

Dependent variable | |

_{1}_{2} |
Degree of freedom |

_{v1}, |
_{1} −1) degrees of freedom |

_{v2}, |
_{2} −1) degrees of freedom |

t | Calculated value of t-statistic |

_{n−k−1;α/2} |
Critical value of “ |

F-distribution parameter (calculated) | |

Level of significance | |

_{k,n−k−1,α} |
Critical value of |

_{1}_{2} |
Independent variables |

_{0}_{1}_{2} |
Unknown parameters, or constants of regression |

Number of independent variable | |

N or n | Random sample size |

R | coefficient of correlation |

H_{0} |
null hypothesis |

_{1}_{2} |
Alternate hypothesis |

d.f. | Degree of freedom |

R^{2} |
Coefficient of determination |

H | Height |

A | Age |

Particulate concentration for different activities

1 | Normal Quarry Environment | 4800 μg/m^{3} |
1 |

2 | Dressing | 9300 μg/m^{3} |
2 |

3 | Drilling | 18500 μg/m^{3} |
3 |

Category of workers and exposure duration

Labour (132) | 0–5 | 26 | 1 |

5–10 | 31 | 2 | |

10–15 | 29 | 3 | |

>15 | 46 | 4 | |

| |||

Dresser (126) | 0–5 | 27 | 1 |

5–10 | 33 | 2 | |

10–15 | 31 | 3 | |

>15 | 35 | 4 | |

| |||

Driller (116) | 0–5 | 26 | 1 |

5–10 | 33 | 2 | |

10–15 | 28 | 3 | |

>15 | 29 | 4 | |

| |||

Control workers | ---------- | 45 | ------ |

Age wise distribution of workers

<20 Yr. | 15.78 | 24.44 |

20–30 Yr. | 42.51 | 26.67 |

30–40 Yr. | 28.34 | 33.33 |

40–50 Yr. | 10.43 | 8.89 |

>50 Yr. | 2.94 | 6.67 |

Mean values of index

26 | Labour | 0–5 | 1 | 1 | 0.5296 |

31 | Labour | 5–10 | 2 | 1 | 0.5351 |

29 | Labour | 10–15 | 3 | 1 | 0.5317 |

46 | Labour | >15 | 4 | 1 | 0.5884 |

27 | Dresser | 0–5 | 1 | 2 | 0.5384 |

33 | Dresser | 5–10 | 2 | 2 | 0.5726 |

31 | Dresser | 10–15 | 3 | 2 | 0.6176 |

35 | Dresser | >15 | 4 | 2 | 0.6448 |

26 | Driller | 0–5 | 1 | 3 | 0.5969 |

33 | Driller | 5–10 | 2 | 3 | 0.6469 |

28 | Driller | 10–15 | 3 | 3 | 0.6483 |

29 | Driller | >15 | 4 | 3 | 0.6734 |

45 | Control Population | --- | --- | 0.3209 |

Values of Statistical parameters

R | 0.961 |

R –Square | 0.924 |

F | 55.006 |

_{0} |
0.435, (t=27.243) |

_{1} |
0.02526, (t=6.131) |

_{2} |
0.04801, (t=8.510) |

Std. error of the estimate | 0.0159579 |

Tests for equality of means of exposed and control population for IFVC

Worker Cat | Excat | n | MIFVC | VRIFVC | F | F_{v1, v2,0.05} |
S_{p} |
t | w_{1} |
t_{1}_{α}_{/2} |
t_{cr} |
t_{c} |
TEST |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|

Labour | 1 | 26 | 0.5296 | 0.01149 | 1.119 | 1.753 | 0.01116 | 75.9288 |
-------- | ------- | ------- | ----- | t-test |

Labour | 2 | 31 | 0.5351 | 0.01180 | 1.142 | 1.720 | 0.01131 | 81.1394 |
-------- | ------- | ------ | ------ | t-test |

Labour | 3 | 29 | 0.5317 | 0.01881 | 1.823 |
1.733 | ------- | ------- | 0.00067 | 2.0480 | 2.0394 | 6.98895 | Cochran-Cox |

Labour | 4 | 46 | 0.5884 | 0.01989 | 1.900 |
1.645 | ------- | ------- | 0.00044 | 2.0160 | 2.0157 | 10.25850 | Cochran-Cox |

Dresser | 1 | 27 | 0.5384 | 0.00296 | 3.477 |
1.838 | ------- | ------- | 0.00011 | 2.0560 | 2.0283 | 11.59480 | Cochran-Cox |

Dresser | 2 | 33 | 0.5726 | 0.01304 | 1.261 | 1.708 | 0.01186 | 92.5894 |
------- | ------- | ------ | ------- | t-test |

Dresser | 3 | 31 | 0.6176 | 0.01957 | 1.889 |
1.720 | ------ | ------- | 0.00065 | 2.0420 | 2.0348 | 9.94380 | Cochran-Cox |

Dresser | 4 | 35 | 0.6448 | 0.01306 | 1.258 | 1.696 | 0.01190 | 120.764 |
------ | ------ | ------- | ------ | t-test |

Driller | 1 | 26 | 0.5969 | 0.00295 | 3.481 |
1.858 | ------- | --------- | 0.00012 | 2.0600 | 2.0299 | 14.63055 | Cochran- Cox |

Driller | 2 | 33 | 0.6469 | 0.00561 | 1.855 |
1.752 | ------- | -------- | 0.00018 | 2.0360 | 2.0239 | 16.03562 | Cochran-Cox |

Driller | 3 | 28 | 0.6483 | 0.01018 | 1.006 | 1.824 | 0.01065 | 127.712 |
------ | ------ | ------ | ------ | t-test |

Driller | 4 | 29 | 0.6734 | 0.00612 | 1.689 | 1.798 | 0.00901 | 164.340 |
------- | ------- | ------ | ------ | t-test |

Control Population | 45 | 0.3209 | 0.01047 | ------ | ------- | -------- | w_{2}=0.00024 |
t_{2}_{α}_{/2} =2.0150 |
------ | ------- | -------- |

The critical value of ‘t’ i.e_{n1 + n2 − 2;α}

Significant values of the test statistic under consideration.