Respiratory symptoms and illnesses related to the concentration of airborne particulate matter among brick kiln workers in Kathmandu valley, Nepal

BACKGROUND: Bricks have been manufactured in Nepal for hundreds of years and are seen as a component of Nepalese sculpture and architecture. Large quantities of hazardous materials including high concentrations of particulate matter are emitted on a daily basis from brick kilns. Exposure to these hazardous materials can lead to adverse consequences on the environment and human health. This study was conducted to  estimate the prevalence of respiratory symptoms/illnesses and the magnitude of respirable and total dust exposures among Nepalese brick kiln workers. METHODS: Respiratory symptoms/illnesses were evaluated by questionnaire among brickfield workers (n = 400) and a referent group of grocery workers (n = 400) in Kathmandu valley. Work zones (WZs): green brick molding (GBM), green brick stacking/carrying (GBS/C), red brick loading/carrying (RBL/C), coal preparation (CP) and firemen (FM) were the similar exposure groups (SEGs) from where personal air samples and interviews were taken. Among brickfield workers, personal monitoring was conducted across SEGs for total (n = 89) and respirable (n = 72) dust during February–March 2015 and March–April 2016. Applying multi-stage probability proportionate to size sampling technique, 16 kilns and 400 brick workers for interview were selected. Proportions, means, medians and ranges were calculated for the demographics, samples and respiratory symptoms/illnesses. One-way ANOVA was applied to compare the significance differences of the level of particulate matter among SEGs. Bivariate and multivariate logistic regression analysis were performed to evaluate association between respiratory symptoms/illnesses and participants groups, and SEGs among brick kiln workers at 0.05 level. Statistical analyses were performed using IBM SPSS Statistics 21. RESULTS: Chronic cough (14.3%), phlegm (16.6%) and bronchitis (19.0%) were higher (P < 0.05) among brickfield compared with grocery workers (6.8, 5.8 and 10.8%). Mean respirable (5.888 mg/m3) and total (20.657 mg/m3) dust exposures were highest for red brick loading tasks. The prevalence of chronic cough, chronic phlegm, chronic bronchitis, wheezing and asthma were significantly higher for other WZs workers (p < 0.05) compared with CP; for GBM: 22.9, 34.6, 15.0 and 7.5%; for GBS/C: 13.5, 15.8, 10.0, 8.8 and 7.5%; for RBL/C: 11.1, 17.1, 27.4, 19.0 and 11.9%; for FM: 18.4, 12.5, 28.4, 4.9 and 0.0%; and for CP: 4.9, 6.3, 13.3, 9.3 and 4.0% respectively. CONCLUSION: High dust exposures identified in this study may explain the increased prevalence of respiratory symptoms/illnesses among Nepalese brickfield workers, warranting action to reduce exposures.

The Similar Exposure Group and Exposure Variation in Ship-Building Painters: Focused on Xylene Exposure / 대한산업의학회지

OBJECTIVES: This study was conducted to assess the concentration of xylene exposure and exposure variability of a similar exposure group(SEG) in accordance with job title and confined space. METHOD: The study subjects included 28 workers working in the painting process in the ship-building industry. Measurement of subjects were repeated three times. Within and between-worker exposure variance components were estimated from log-transformed exposure concentrations employing a one-way nested random effects analysis of variance model. A uniformly exposed group was defined as one where the between-worker variance(sigmaB2) was less than or equal to 0.031 or bwR95 or=0.031) and the ratios of the 97.5th and 2.5th percentile workers of the log normally distributed exposures of each group of workers was more than 2. However dividing job title into confined space(in-block, out-block, in/out-block) decreased the between-worker exposure variability. CONCLUSION: This study focused on the quantitative aspects of exposure in painters in the ship-building industry. We cannot accept the assumption that SEG are uniformly exposed, as a major component of variation in exposure relates to differences in tasks or other factors. Therefore, the observational schemes can be improved by investigating jobspecific task and practice.