Personal exposure to inhalable cement dust among construction workers

Mitigation strategies to reduce particulate matter concentrations in civil engineering laboratories

In the departments of civil engineering, many experiments are conducted in laboratories for educational and research purposes. Varying degrees of respirable dust are generated as the outcome of these experiments, which could cause harm to instructors' and students' health. This study is devised to highlight the importance of indoor air quality in university laboratories. As part of the research, four different particulate matter (PM) sizes (PM1.0, PM2.5, PM4.0, and PM10) were measured during specific experiments-sieve analysis, preparation of the concrete mixture, crushing aggregate by jaw crusher, dynamic triaxial compression test, sieve analysis of silt specimen, cleaning sieve by an air compressor, and proctor compaction test-being conducted periodically in the laboratories of civil engineering departments. The measured values are mainly high compared to indoor air quality standards. Mitigation strategies were applied to reduce indoor air PM levels in the three experiments that contained the highest PM levels. The results have shown that mitigation strategies applied as control measures could make a remarkable difference in protecting instructors and civil engineering students.

Health damage assessment of reconstruction dust from old industrial buildings under multi-process

The regeneration of old industrial buildings produces considerable construction dust, thereby seriously threatening the occupational health of construction workers. The existing articles concerning the exposure and health impacts of reconstruction dust in enclosed spaces are limited, but this research field has received increasing attention. In this study, multi-process during the demolition and reinforcement stages of a reconstruction project were monitored to determine the respirable dust concentration distribution. A questionnaire survey was conducted to obtain the exposure parameters of reconstruction workers. Moreover, a health damage assessment system for the reconstruction process of old industrial buildings was established by applying the disability-adjusted life year and human capital method to explore the health damage caused by the generated dust at different stages to the construction personnel. The assessment system was applied to the reconstruction stage of an old industrial building regeneration project in Beijing to obtain dust health damage values for different work types and to conduct comparative analysis. The results indicate that there are significant differences in the dust concentration and health damage at different stages. During the demolition stage, the manual demolition of concrete structures has the highest dust concentration, reaching 0.96 mg/m³. This exceeds the acceptable concentration by 37%, and the health damage cost is 0.58 yuan per person per day. In the reinforcement stage, the dust concentration generated by mortar/concrete mixing is the highest, but the risk level is acceptable. The health damage cost of concrete grinding, which is 0.98 yuan per person per day, is the highest. Therefore, it is necessary to strengthen the protective facilities and improve the reconstruction technology to reduce dust pollution. The results of this study can help in improving the existing dust pollution control measures at construction sites to reduce the risk of dust hazards during reconstruction.

Exposure to construction dust and health impacts - A review

Construction dust contributes a significant proportion of airborne particulate matter, affecting the health of its surrounding environment and population. Construction workers are normally exposed to dust at high levels and bear severe health risks. The existing articles concerning the exposure and health impacts of construction dust are limited, but this research field has received more and more attention. This work reviews literature in the field and tries to systematically assess the current research state. Here, we review (1) methods used to monitor or sample construction dust; (2) main characteristics of construction dust, including dust classification, exposed populations, and exposure concentrations; (3) potential health hazards and (4) health risk assessment of construction dust. From existing literature, the exposure concentrations of different types and sources of construction dust are usually the focus of attention, while its particle size distribution and chemical composition are rarely mentioned. The classification and characteristics of populations exposed to construction dust ought to be a key consideration but not clear enough so far. There still lacks in-depth study of health hazards and systematic assessment of risks associated with construction dust. In future, it is valuable to develop utility instruments to precisely monitor construction dust. Besides, control means to reduce the pollution of construction dust deserve more studies. Health hazards of construction dust should be verified by biological experiments. Moreover, emerging algorithm models should be utilized in the risk assessment. The findings will help gain a better understanding of construction dust exposure and associated health risks.

Empirical Analysis of Dust Health Impacts on Construction Workers Considering Work Types

In the construction industry, workers are exposed to hazardous emissions, such as dust, and various diseases, such as chronic obstructive pulmonary disease (COPD), which affect workers. There is, however, a lack of studies that evaluate the dust that workers are exposed to, taking into account different factors of dust. Therefore, this study aims to estimate the amount of dust construction workers are exposed to by considering different factors of dust emission and to assess the health and economic impact of dust emissions. This study is conducted in three steps: (1) scope definition, (2) definition of worker dust exposure, and (3) health impact assessment. As a result, dust concentrations from the energy used, the atmosphere, and during construction activities were 1.01 × 10−5 µg/m3, 37.50 µg/m3, and 1.33 × 104 µg/m3 respectively. Earthwork had the highest dust concentration of 3.85 × 103 µg/m3. The total added number of disability-adjusted life years (DALY) of workers was 0.0542a with an economic cost of $13,691.00. The contributions of this study are the accurate assessment of the amount of dust workers are exposed to and the development of policies to help compensate construction workers suffering from dust emission-related diseases.

Environmental Particulate Matter (PM) Exposure Assessment of Construction Activities Using Low-Cost PM Sensor and Latin Hypercubic Technique

Dust generation is generally considered a natural process in construction sites; ergo, workers are exposed to health issues due to fine dust exposure during construction work. The primary activities in the execution of construction work, such as indoor concrete and mortar mixing, are investigated to interrogate and understand the critical high particulate matter concentrations and thus health threats. Two low-cost dust sensors (Sharp GP2Y1014AU0F and Alphasense OPC N2) without implementing control measures to explicitly evaluate, compare and gauge them for these construction activities were utilized. The mean exposures to PM10, PM2.5 and PM1 during both activities were 3522.62, 236.46 and 47.62 µg/m3 and 6762.72, 471.30 and 59.09 µg/m3, respectively. The results show that PM10 and PM2.5 caused during the concrete mixing activity was approximately double compared to the mortar. The Latin Hypercube Sampling method is used to analyze the measurement results and to predict the exposure concentrations. The high dust emission and exposure from mixing activities fail to meet the World Health Organization and Health and Safety Commission standards for environmental exposure. These findings will leverage the integration of low-cost dust sensors with Building Information Modelling (BIM) to formulate a digital twin for automated dust control techniques in the construction site.

Occupational Cement Dust Exposure and Inflammatory Nemesis: Bangladesh Relevance

Background

Prolonged, repeated exposure to cement dust, depending on duration and sensitivity of cement dust-exposed workers, may cause deteriorating effects on the skin, eye, respiratory and hematological system. Toxic cement dust causes inflammatory damage to different body organs. White blood cells (WBCs) are considered cellular markers of ongoing tissue inflammation.

Aim of the Study

Determining the influence of occupational cement dust exposure on WBCs with its differentials (inflammatory markers) in workers from the cement manufacturing plant.

Methodology

Ninety-two seemingly healthy male subjects (46 workers of cement plant and 46 control subjects, who do not contact cement dust, residing in Dhaka) aged between 20 and 50 years participated in this cross-sectional study. This study took place in Dhaka Medical College, Bangladesh, between the years of 2017 and 2018. An automated hematoanalyser was used to assess both the total and differential count of WBC. Data were analyzed with multivariate regression analysis, independent samples t-test, and correlation test.

Results

The total WBC count, differential count of lymphocyte, and eosinophil were significantly (p< 0.05) higher in cement dust-exposed recruits than in the control group. Additionally, multivariate regression analysis revealed that duration of cement dust exposure showed a significant association with total WBC count [odds ratio (OR)=4.42,95%, confidence level (CI) 1.56,12.47, p 0.005]. Furthermore, univariate analysis revealed that the control group (not exposed to cement dust) was less likely to have the total WBC count alteration (OR = 0.122, 95% CI =0.047 to 0.311) than the cement dust-exposed group. The total WBC count showed a significant positive correlation with exposure duration to this toxic dust.

Conclusion

Cement dust exposure causes harmful inflammatory responses, as evidenced by increased total and differential WBC count. The period of contact with this toxic dust has an impact on WBC count.

Standardized experimental model for cement dust exposure; tissue heavy metal bioaccumulation and pulmonary pathological changes in rats

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Exposure model is a reliable method of studying pulmonary toxicity of aerosolized xenobiotics.

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Deposition of particles beyond the conducting zone and tissue bioaccumulation accompany exposure to cement dust (ECD).

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Histoarchitectural alteration, body-organ weight discordance are indicators of acute ECD.

A controlled experimental model of exposure to aerosols particularly for cement dust was recently invented in a study from the laboratory that found high serum levels of heavy metals, decrease gastrointestinal motility, and altered hematological variables in cement dust exposed rats. However, reproducibility was not considered. This work aims at standardizing the model and investigating preliminary toxicological indicators. Thirty male rats used in this study were divided into 3 groups (n = 10). Group 1; control, while groups 2 and 3 were exposed to cement dust for 14 days and 28 days respectively. We assessed clinical signs of toxicity, tissue heavy metal concentration, histopathological, and body weight (BW) changes. We observed poor movement coordination, abnormal posture, cephalic fur loss. Evidence of ischemia and fibrotic pneumoconiosis were grossly observed in the lungs of the exposed groups. There was a significant increase in tissue level of heavy metals with pulmonary and gastric heavy metal content showing a trendy relationship during the period of the exposure as the value of Lead, Chromium, Cadmium, Iron, Calcium, and Nickel increased by nearly similar percentages in both tissues. Organs weights increased; the 14-day exposed (198 ± 31; 168 ± 22) and 28-day exposed (198 ± 22; 187 ± 26) groups had significantly reduced body weight at the first and second weeks of exposure compared to the control group (265 ± 26; 357 ± 40) respectively. Exposure to cement dust induced low bone density in the exposed rats (p < 0.05). Histopathological alterations include necrosis, inflammatory cellular infiltration, and alveolar hyperplasia suggestive of the proliferative response of pulmonary tissue to the dust. The operation of the standardized apparatus mimics a typical occupational exposure and the findings show that cement dust induces systemic toxicity via respiratory perturbation and body/organ weight discordance mediated by heavy metal bioaccumulation.

The relationship between cement production, mortality rate, air quality, and economic growth for China, India, Brazil, Turkey, and the USA: MScBVAR and MScBGC analysis

The related literature reveal that the papers on environmental pollution do not sufficiently analyse the cement production which is an important determinant of air pollution and health problems by using econometric methods. To fill this gap, this paper aims to examine the relationship between cement production, air pollution, mortality rate, and economic growth by employing MS Bayesian Vector Autoregressive (MScBVAR) and Markov Switching Bayesian Granger causality (MScBGC) approaches from 1960 to 2017 for China, Brazil, India, Turkey and the USA. MSIA(2)-BVAR(1) model for China, MSIAH(2)-BVAR(3) models for India, MSIAH(3)-BVAR(2) for Brazil, and MSIAH(3)-BVAR(1) for Turkey, and MSIAH(2)-BVAR(2) for the USA were selected. The MScBGC results revealed that the cement production is granger cause of mortality rate, air pollution, and economic growth in all regimes for China, India, Brazil, Turkey, and the USA.

Life cycle assessment of concrete production with a focus on air pollutants and the desired risk parameters using genetic algorithm

BACKGROUND

Through a new systematic perspective, the HSE-integrated management system attempts to examine the relationships between safety, health and environment. The purpose of this system is to provide a coordinated, comprehensive and precautionary assessment of the issues and incidents within concrete plants.

METHODS

In addition to a life cycle assessment (LCA) of concrete through air pollutant emissions in this study, the extraction and monitoring of pollutant from three concrete plants in the city of Mashhad are carried out via fieldwork. In the present study, a number of factors such as the extent and time of exposure to each pollutant are estimated using the meta-heuristic genetic algorithm approach (GA) in order to create the desirable risk rate (risk rate ≤ 3).

RESULTS

The results of life cycle assessment indicate the production of 348 kg Carbon Dioxide (CO₂) per cubic meter of concrete processing. However, in addition to its environmental effects, CO₂ in concentrations of more than 5000 ppm may cause asphyxiation as well as epidemiologic effects on the staff.

CONCLUSION

The results of the study show that in order to reduce the risks of developing chronic diseases such as lung cancer, the staff in cement processing sector must be exposed to a period of at most 3.5 h for each 8-h work interval.

Sequential Extractions and Toxicity Potential of Trace Metals Absorbed into Airborne Particles in an Urban Atmosphere of Southwestern Nigeria

The paper investigates the hypothesis that biotoxicities of trace metals depend not only on the concentration as expressed by the total amount, but also on their geochemical fractions and bioavailability. Airborne particles were collected using SKC Air Check XR 5000 high volume Sampler at a human breathing height of 1.5–2.0 meters, during the dry season months from November 2014 to March 2015 at different locations in Akure (7°10′N and 5°15′E). The geochemical-based sequential extractions were performed on the particles using a series of increasingly stringent solutions selected to extract metals (Cd, Cu, Cr, Ni, Pb, Zn, and Mn) into four operational geochemical phases—exchangeable, reducible, organic, and residual—and then quantified using an Atomic Absorption Spectrophotometer. The results showed metals concentration of order Pb > Cr > Cd > Zn > Ni > Cu > Mn. However, most metals in the samples exist in nonmobile fractions: exchangeable (6.43–16.2%), reducible (32.58–47.39%), organic (4.73–9.88%), and residual (18.28–27.53%). The pollution indices show ingestion as the leading route of metal exposure, with noncarcinogenic (HQ) and cancer risk (HI) for humans in the area being higher than 1.0 × 10⁻⁴, indicating a health threat.

15 years of monitoring occupational exposure to respirable dust and quartz within the European industrial minerals sector

INTRODUCTION

In 2000, a prospective Dust Monitoring Program (DMP) was started in which measurements of worker's exposure to respirable dust and quartz are collected in member companies from the European Industrial Minerals Association (IMA-Europe). After 15 years, the resulting IMA-DMP database allows a detailed overview of exposure levels of respirable dust and quartz over time within this industrial sector. Our aim is to describe the IMA-DMP and the current state of the corresponding database which due to continuation of the IMA-DMP is still growing. The future use of the database will also be highlighted including its utility for the industrial minerals producing sector.

METHODS

Exposure data are being obtained following a common protocol including a standardized sampling strategy, standardized sampling and analytical methods and a data management system. Following strict quality control procedures, exposure data are consequently added to a central database. The data comprises personal exposure measurements including auxiliary information on work and other conditions during sampling.

RESULTS

Currently, the IMA-DMP database consists of almost 28,000 personal measurements which have been performed from 2000 until 2015 representing 29 half-yearly sampling campaigns. The exposure data have been collected from 160 different worksites owned by 35 industrial mineral companies and comes from 23 European countries and approximately 5000 workers.

CONCLUSION

The IMA-DMP database provides the European minerals sector with reliable data regarding worker personal exposures to respirable dust and quartz. The database can be used as a powerful tool to address outstanding scientific issues on long-term exposure trends and exposure variability, and importantly, as a surveillance tool to evaluate exposure control measures. The database will be valuable for future epidemiological studies on respiratory health effects and will allow for estimation of quantitative exposure response relationships.

Thoracic dust exposure is associated with lung function decline in cement production workers

We hypothesised that exposure to workplace aerosols may lead to lung function impairment among cement production workers.

Our study included 4966 workers in 24 cement production plants. Based on 6111 thoracic aerosol samples and information from questionnaires we estimated arithmetic mean exposure levels by plant and job type. Dynamic lung volumes were assessed by repeated spirometry testing during a mean follow-up time of 3.5 years (range 0.7–4.6 years). The outcomes considered were yearly change of dynamic lung volumes divided by the standing height squared or percentage of predicted values. Statistical modelling was performed using mixed model regression. Individual exposure was classified into quintile levels limited at 0.09, 0.89, 1.56, 2.25, 3.36, and 14.6 mg·m⁻³, using the lowest quintile as the reference. Employees that worked in administration were included as a second comparison group.

Exposure was associated with a reduction in forced expiratory volume in 1 s (FEV₁), forced expiratory volume in 6 s and forced vital capacity. For FEV₁ % predicted a yearly excess decline of 0.84 percentage points was found in the highest exposure quintile compared with the lowest.

Exposure at the higher levels found in this study may lead to a decline in dynamic lung volumes. Exposure reduction is therefore warranted.

Cement dust exposure at levels comparable to stated workplace exposure limits may lead to obstructive lung changeshttp://ow.ly/Zl7ny

Lung cancer risk among bricklayers in a pooled analysis of case-control studies

Bricklayers may be exposed to several lung carcinogens, including crystalline silica and asbestos. Previous studies that analyzed lung cancer risk among these workers had several study design limitations. We examined lung cancer risk among bricklayers within SYNERGY, a large international pooled analysis of case-control studies on lung cancer and the joint effects of occupational carcinogens. For men ever employed as bricklayers we estimated odds ratios (OR) and 95% confidence intervals (CI) adjusted for study center, age, lifetime smoking history and employment in occupations with exposures to known or suspected lung carcinogens. Among 15,608 cases and 18,531 controls, there were 695 cases and 469 controls who had ever worked as bricklayers (OR: 1.47; 95% CI: 1.28-1.68). In studies using population controls the OR was 1.55 (95% CI: 1.32-1.81, 540/349 cases/controls), while it was 1.24 (95% CI: 0.93-1.64, 155/120 cases/controls) in hospital-based studies. There was a clear positive trend with length of employment (p < 0.001). The relative risk was higher for squamous (OR: 1.68, 95% CI: 1.42-1.98, 309 cases) and small cell carcinomas (OR: 1.78, 95% CI: 1.44-2.20, 140 cases), than for adenocarcinoma (OR: 1.17, 95% CI: 0.95-1.43, 150 cases) (p-homogeneity: 0.0007). ORs were still elevated after additional adjustment for education and in analyses using blue collar workers as referents. This study provided robust evidence of increased lung cancer risk in bricklayers. Although non-causal explanations cannot be completely ruled out, the association is plausible in view of the potential for exposure to several carcinogens, notably crystalline silica and to a lesser extent asbestos.

The impact of reduced dust exposure on respiratory health among cement workers: an ecological study

OBJECTIVES

To compare total dust exposure, prevalence of chronic respiratory symptoms, lung function, and chronic obstructive pulmonary disease (COPD) among Tanzanian cement workers before (2002) and after (2010-2011) establishment of dust-control measures.

METHODS

Personal total dust-exposure measurements, questionnaire assessment for chronic respiratory symptoms, and spirometry were conducted in both examination periods.

RESULTS

Total dust exposure was lower in 2010-2011 than in 2002. The prevalence of most chronic respiratory symptoms and COPD was lower in 2010 than in 2002. Forced expiratory volume in 1 second (FEV1), percentage predicted FEV1, and percentage predicted forced vital capacity were higher among cement workers in 2010 than in 2002.

CONCLUSIONS

There was reduced total dust exposure level, lower prevalence of chronic respiratory symptoms and COPD, and higher lung function among cement workers in 2010 than in 2002.

Fractional exhaled nitric oxide among cement factory workers: a cross sectional study

BACKGROUND

It has been suggested that dust exposure causes airway inflammation among cement factory workers. However, there is limited information on the mechanisms of this effect. We explored any associations between total dust exposure and fractional exhaled nitric oxide (FENO) as a marker of airway eosinophilic inflammation among cement production workers in Tanzania. We also examined possible differences in FENO concentration between workers in different parts of the production line.

METHODOLOGY

We examined 127 cement workers and 28 controls from a mineral water factory. An electrochemistry-based NIOX MINO device was used to examine FENO concentration. Personal total dust was collected from the breathing zone of the study participants using 37 mm cellulose acetate filters placed in three-piece plastic cassettes. Interviews on workers' background information were conducted in the Swahili language.

RESULTS

We found equal concentrations of FENO among exposed workers and controls (geometric mean (GM)=16 ppb). The GM for total dust among the exposed workers and controls was 5.0 and 0.6 mg/m(3), respectively. The FENO concentrations did not differ between the exposed workers with high (GM≥5 mg/m(3)) and low (GM<5 mg/m(3)) total dust exposure. There was no significant difference in FENO concentration between workers in the two main stages of the cement production process.

CONCLUSIONS

We did not find any difference in FENO concentration between dust-exposed cement workers and controls, and there were similar FENO concentrations among workers in the two main stages of cement production.

Determinants of exposure to dust and dust constituents in the Norwegian silicon carbide industry

INTRODUCTION

The aim of this study was to identify important determinants of dust exposure in the Norwegian silicon carbide (SiC) industry and to suggest possible control measures.

METHODS

Exposure to total dust, respirable dust, quartz, cristobalite, SiC, and fiber was assessed in three Norwegian SiC plants together with information on potential determinants of exposure. Mixed-effect models were constructed with natural log-transformed exposure as the dependent variable.

RESULTS

The exposure assessment resulted in about 700 measurements of each of the sampled agents. Geometric mean (GM) exposure for total dust, respirable dust, fibers, and SiC for all workers was 1.6mg m(-3) [geometric standard deviation (GSD) = 3.2], 0.30mg m(-3) (GSD = 2.5), 0.033 fibers cm(-3) (GSD = 5.2), and 0.069mg m(-3) (GSD = 3.1), respectively. Due to a large portion of quartz and cristobalite measurements below the limit of detection in the processing and maintenance departments (>58%), GM for all workers was not calculated. Work in the furnace department was associated with the highest exposure to fibers, quartz, and cristobalite, while work in the processing department was associated with the highest total dust, respirable dust, and SiC exposure. Job group was a strong determinant of exposure for all agents, explaining 43-82% of the between-worker variance. Determinants associated with increased exposure in the furnace department were location of the sorting area inside the furnace hall, cleaning tasks, building and filling furnaces, and manual sorting. Filling and changing pallet boxes were important tasks related to increased exposure to total dust, respirable dust, and SiC in the processing department. For maintenance workers, increased exposure to fibers was associated with maintenance work in the furnace department and increased exposure to SiC was related to maintenance work in the processing department.

CONCLUSION

Job group was a strong determinant of exposure for all agents. Several tasks were associated with increased exposure, indicating possibilities for exposure control measures. Recommendations for exposure reduction based on this study are (i) to separate the sorting area from the furnace hall, (ii) minimize manual work on furnaces and in the sorting process, (iii) use remote controlled sanders/grinders with ventilated cabins, (iv) use closed systems for filling pallet boxes, and (v) improve cleaning procedures by using methods that minimize dust generation.

Time trend in hospitalised chronic lower respiratory diseases among Danish building and construction workers, 1981-2009: a cohort study

OBJECTIVES

To show trends in age-standardised hospital admission ratios (SHR) for chronic lower respiratory diseases, estimated for Danish construction workers over three time periods (1981-1990, 1991-2000, 2001-2009).

DESIGN

Within consecutive cohorts of all male building and construction workers in Denmark, selected occupations: bricklayers, carpenters, electricians, painters, plumbers and 'other construction workers' were followed up for hospitalisation due to chronic lower respiratory diseases. SHR was calculated for each occupation and time period. Time trend was calculated for construction workers at large using Poisson regression.

SETTING

Denmark.

PARTICIPANTS

All gainfully employed male building and construction workers aged 20 or more.

PRIMARY AND SECONDARY OUTCOME MEASURES

Age-standardised and gender-standardised hospitalisation ratios (SHR).

RESULTS

The number of hospitalised construction workers at large was reduced from 1134 in the first 10-year period to 699 in the last 9-year period. Among all Danish males, it was, however, even more reduced as reflected in the expected number that was down from 1172 to 617. Hence, SHR increased from 97 during 1981-1990, 100 during 1991-2000 to 113 during 2001-2009. It means that SHR increased with an average rate of 0.76% per year (95% CI 0.28 to 1.24) during the study period. A low SHR=72 (95% CI 60 to 87) was found among carpenters in 1981-1990. From 2001 to 2009, high SHRs were found among painters (SHR=147; 95% CI 111 to 192) and plumbers (SHR=132; 95% CI 101 to 171). In general, the selected groups of construction workers had, however, a low or average SHR due to chronic lower respiratory diseases.

CONCLUSIONS

The number of hospitalised workers, suffering from chronic lower respiratory diseases, was reduced over time for construction workers, but for all economically active men, it was reduced even more. Therefore, SHR due to chronic lower respiratory diseases increased over time in the construction industry at large.

Cement dust exposure-related emphysema in a construction worker

Although, smoking is considered the most important predisposing factor in development of emphysema; environmental exposures also play an important role. There have been several studies on work related respiratory symptoms and ventilatory disorders among employees of cement industry. We report a case of cement exposure related emphysema in 75 years old woman construction worker.

Excessive exposure to dust among cleaners in the Ethiopian cement industry

Personal exposure to dust in cement factories occurs at all stages of the production process and is likely to vary between different stages of the process. Previous studies on cement production have focused on dust exposure among process operators and machine attendants. This study characterizes personal exposure to total and respirable dust among production workers in two cement factories in Ethiopia, with particular focus on cleaners. In Ethiopian cement plants, flow lines are partly open, and cleaning workers use brooms and shovels to remove dust that has settled on floors and machines. Personal full-shift samples of total (n = 150) and respirable dust (n = 36) were taken in the breathing zones of 105 cement workers. Samples of total and respirable dust were collected on 37-mm cellulose acetate filters of closed-face cassettes and in plastic respirable cyclones, respectively. In both factories, cleaners had significantly higher exposures to total and respirable dust than other production workers. Among cleaners, the geometric means for total and respirable dust exposure were 549 and 6.8 mg/m(3) in Factory A, and 153 and 2.8 mg/m(3) in Factory B. Temporal variability (within-worker) dominated the variability in the cleaners' total dust exposures. The distance from machines while performing cleaning tasks and the fraction of working hours spent on cleaning explained about 73% of the temporal variability in total dust exposure among cleaners. Only 7% of the production workers used respiratory protective devices. Preventive measures are needed to reduce dust exposure.

Influence of compressive strength and applied force in concrete on particles exposure concentrations during cutting processes

The objective of this research was to identify the influence of applied force (AF) and the compressive strength (CS) of concrete on particle exposure concentrations during concrete cutting processes. Five cutting conditions were selected with AF varied between 9.8 and 49 N and CS varied between 2500 and 6000 psi. For each selected cutting condition, the measured total dust concentrations (C(tot)) were used to further determine the corresponding three health-related exposure concentrations of the inhalable (C(inh)), thoracic (C(thor)), and respirable fraction (C(res)). Results show that particle size distribution was consistently in a bimodal form under all selected cutting conditions. An increase in CS resulted in an increase in coarse particle generations leading to an increase in the four measured particle exposure levels. An increase in AF resulted in an increase in exposure concentrations with a higher fraction of fine particles (i.e., C(tho) and C(res)) However, for particle exposure concentrations with a higher fraction of coarse particles (i.e., C(tot) and C(inh)), an increase in AF resulted in an initial increase, followed by a decrease in concentration. Finally, the above inferences were further confirmed through the use of fixed-effect models to determine the influence of both CS and AF on the four exposure concentrations. These results provide a reference for industries to initiate appropriate control strategies to reduce the exposure levels encountered by workers.