The variation of hardness of rhombohedral single crystals of calcite ~md sodium nitrate with quenching temperature is studied. Vickers and Knoop hardness numbers are determined tram the indentations produced on freshly-cleaved crystal surfaces for various loads. The variation ,Jf hardness number with quenching temperature can be represented by H~q = constant where ~he exponent k is less than unity and its sign determines the nature of maferial.

It is well known that an exposure to crystalline silica gives rise to silicosis and silico-tuberculosis (TB). In the agate industry of Khambhat (Gujarat) not only workers but also people staying in the vicinity of the agate-grinding facilities are exposed to crystalline silica. To reduce their dust exposure, dust control devices were developed. There are approximately 500 grinding machines located in Khambhat. A cost–benefit analysis of installing dust control devices on all agate-grinding machines was carried out by adding all positive factors and benefits and subtracting the negatives and costs. It was concluded that by installing dust control devices not only could the prevalence of silicosis and TB be reduced but also, in the long run, there could be financial benefits.

Non-occupational exposure to crystalline silica (quartz) in vicinity of slate pencil industry is reported. Ambient silica monitoring was carried out at two locations in the vicinity of slate pencil industry and one control site 5 kilometers away from slate pencil industry using PM-10 high volume samplers. Quartz content was analyzed using Fourier Transform Infrared Spectrophotometer (FTIR) from vertically elutriated dust samples collected simultaneously at all locations. It was found that average quartz concentrations in the vicinity of slate pencil industry and control site were 41.07-57.22 and 3.51 microg/m(3), respectively. Results were compared with derived ambient air quality standard for silica based on findings reported by Environmental Protection Agency (EPA).

In an epidemiological study carried out in three textile mills at Ahmedabad, India, 929 workers were examined from the spinning departments. The mean prevalence of byssinosis in the blow section was 29-62%, whereas in the card section it was 37-83%. The concentrations of cotton dust (dust less fly) were high in the blow and card sections (4 00 mg/m3 in the blow and 3-06 mg/m3 in the card section). This study suggests that the prevalence of byssinosis is not low in the textile mills of India as reported in many earlier Indian studies.Byssinosis is an occupational lung disease often observed among workers exposed to cotton, flax, and hemp dust. The severity and extent of the problem are well recognised in the developed countries and control measures have been implemented to prevent the disease. This is not true, however, for the developing countries where the severity and extent of the problem are not well studied and preventive measures are virtually non-existent.' In India several studies on byssinosis were undertaken in the past23 (and KC Thiruvengadam in 1967 and JR Sen in 1968 at Indian Council of Medical Research, New Delhi). A review of the earlier studies on byssinosis suggests a low prevalence of the disease in most of the Indian textile mills.3 Our study in one Ahmedabad textile mill, however, showed a high prevalence of the disease, especially in the blow and card sections of the mill.4 The study was extended to two other textile mills in Ahmedabad. The overall findings of the study of three textile mills are presented in the present paper. Material and methodsThree textile mills were included in this study. These mills, selected from different areas of Ahmedabad, Gujarat State, India, were using a medium variety of cotton as the raw material and manufactured only cotton cloth. The ventilation was poor in the blow and card sections of these mills. There was no exhaust device over the carding machines.At the beginning ofthe study we tried to obtain a list of the workers in the spinning department ofeach mill to select a sample based on statistical methods, butAccepted 16 January 1989 none of the managements could give us an exact section list of the workers. Nevertheless, we could obtain the approximate figures for the total (permanent and temporary) number of workers in each mill. There were 530 (480 permanent, 50 temporary) workers in the first mill, 290 (260 permanent, 30 temporary) in the second, and 300 (265 permanent, 35 temporary) in the third. The number of permanent and temporary workers varied slightly on each visit depending on the absence of permanent workers. Since the temporary workers used to get work (badli) for 15-20 days in a month, their exposure was irregular. Therefore, it was decided to exclude them from the study. Thus out of the permanent workers we could examine 452 (94 17%) workers from the first mill, 237 (91-15%) from the second, and 240 (90 57%) from the third. Overall, 929 (92.44%) permanent workers were examined out of 1005 workers. From the four sections of s...

Background:Known respiratory health effects of exposure to cotton dust are mainly altered pulmonary function findings and symptom of chest tightness. A number of studies have been carried out all over the world to enumerate and evaluate the health effects of cotton dust exposed workers in different processes. However, such studies carried out in ginning industry especially in Indian context are scanty.Objectives:This study was initiated to explore occupational and morbidity details and respiratory functional status of the exposed workers as well as to investigate across the working shift pulmonary function changes.Materials and Methods:A cross-sectional study was conducted including workers from ginning units where principal exposure is from cotton dust. All the workers of the selected ginning units were subjected to an interview with a predesigned questionnaire to collect occupational and medical history, clinical examination and pulmonary function test.Results:In this present study, no cross-shift significant change in relation to PEFR and FEV1 values is observed. However, chronic effect on lung function is observed in a few subjects and declining trend of values was observed with increasing job duration as well as age of workers and among smokers. Other health problems among these subjects were backache and joint pain.Conclusions:Studies on cotton textile workers have shown both cross-shift and chronic decline of values. In this study on ginning workers, chronic effect only is observed. This difference of observation may be explained by different nature of exposure in case of ginning. This study recommends regular periodic clinical examination, lung function test and monitoring of dust, gram-negative bacteria and endotoxins in such workplaces.