Asbestos-cement Roofing Research Articles

Quantifying asbestos fibers in post-disaster situations: Preventive strategies for damage control

When buildings that contain asbestos collapse, harmful asbestos fibers can spread in large quantities. It is critical to control this scattering as quickly as possible to protect residents and workers. Rescue and recovery operations in post-disaster situations usually take a lot of time. Therefore, experiments were conducted to evaluate and control the scattering of asbestos fibers. First, the concentration of asbestos fibers released from broken pieces of asbestos cement roofing sheet (ACRS) was measured over time. Next, the broken pieces were classified into three groups (A: no coating, B: water coating; C: asbestos stabilizer coating) and the amount of asbestos fiber released over time was measured to determine the efficiency of asbestos fiber control using water and asbestos stabilizer. The concentration of asbestos fibers generated from broken ACRS was 0.162 f/cc on average. The asbestos fiber control efficiencies of water and asbestos stabilizer showed similar patterns in the early stage. However, the efficiency of the water coating rapidly decreased after 9 h, whereas the asbestos stabilizer coating showed high efficiency even after 36 h. The results of this study will contribute to the establishment of plans for protecting workers and survivors more safely in disaster sites while controlling asbestos fibers.

Asbestos—Cement Roofing Identification Using Remote Sensing and Convolutional Neural Networks (CNNs)

Due to the pathogenic nature of asbestos, a statutory ban on asbestos-containing products has been in place in Poland since 1997. In order to protect human health and the environment, it is crucial to estimate the quantity of asbestos–cement products in use. It has been evaluated that about 90% of them are roof coverings. Different methods are used to estimate the amount of asbestos–cement products, such as the use of indicators, field inventory, remote sensing data, and multi- and hyperspectral images; the latter are used for relatively small areas. Other methods are sought for the reliable estimation of the quantity of asbestos-containing products, as well as their spatial distribution. The objective of this paper is to present the use of convolutional neural networks for the identification of asbestos–cement roofing on aerial photographs in natural color (RGB) and color infrared (CIR) compositions. The study was conducted for the Chęciny commune. Aerial photographs, each with the spatial resolution of 25 cm in RGB and CIR compositions, were used, and field studies were conducted to verify data and to develop a database for Convolutional Neural Networks (CNNs) training. Network training was carried out using the TensorFlow and R-Keras libraries in the R programming environment. The classification was carried out using a convolutional neural network consisting of two convolutional blocks, a spatial dropout layer, and two blocks of fully connected perceptrons. Asbestos–cement roofing products were classified with the producer’s accuracy of 89% and overall accuracy of 87% and 89%, depending on the image composition used. Attempts have been made at the identification of asbestos–cement roofing. They focus primarily on the use of hyperspectral data and multispectral imagery. The following classification algorithms were usually employed: Spectral Angle Mapper, Support Vector Machine, object classification, Spectral Feature Fitting, and decision trees. Previous studies undertaken by other researchers showed that low spectral resolution only allowed for a rough classification of roofing materials. The use of one coherent method would allow data comparison between regions. Determining the amount of asbestos–cement products in use is important for assessing environmental exposure to asbestos fibres, determining patterns of disease, and ultimately modelling potential solutions to counteract threats.

Chemical elimination of asbestos materials

Asbestos was a frequently used material in the past, mainly in the construction industry, on account of its excellent thermal and chemical resistance. Nowadays, all uses, handling and disposal of asbestos materials are subject to strict legislation due to health hazard. This work is a research of an efficient chemical way to decompose these materials with the lowest energy costs possible so that the method could compete with patented thermal decomposition and other currently common methods. Decompositions were performed at room temperature with acids, namely hydrochloric, sulfuric, phosphoric, acetic and oxalic acid and the results were evaluated based on mass analysis. Asbestos rope and asbestos-cement roof tile were used as samples. From the experiments carried out, the best decomposing agent was hydrochloric acid for the rope sample and acid mixture (hydrochloric and acetic acid in a 1:1 ratio). for the roof tile sample

Asbestos Bodies Burden in the Autopsy Lung Tissue from General Thai Population.

Background:Chrysotile asbestos has been used in Thailand for over 30 years mainly in asbestos-cement wall and roof tiles. In non-exposed subject, asbestos fiber can contaminate in ambient indoor and outdoor environments.Objective:The aim of the present study is to evaluate the current prevalence and volume of AB load in general Thai population.Methods:Lung tissues were obtained from 200 autopsy cases. Asbestos Bodies (AB) were identified with light microscopy using the tissue digestion and membrane filtration method. Results are reported as AB/g wet lung tissue.Results:AB was identified in 97(48.5%) out of 200 cases. The AB level ranged from 0.19-14.4 AB/g wet lung. Most of the positive cases (99%) have less than 10 AB/g wet lung. Only one case exhibited a high value at 14.4 AB/g wet lung. Age, gender, occupation and hometown were found to have no effect on AB burden in autopsy lung tissue from this study.Conclusion:The prevalence of AB in autopsy lung tissue from general Thai population is 48.5% and the AB level ranges from 0-14.4 AB/g wet lung in consistent with non-occupational asbestos exposure level regarding several reference reports.

Risk assessment of asbestos-cement roof sheets in Chekka, North Lebanon

Asbestos-cement was manufactured and used in Lebanon since the early 1950s. Corrugated rooftops of asbestos-cement were mostly spread within residential areas throughout the country. These rooftops are subject to weathering factors which are known to increase friability and risk of hazardous fiber release. This study aimed at assessing the asbestos-cement rooftop friability and the possible emerging risks in the urban-industrial city of Chekka, North Lebanon. The evaluation of the asbestos-cement included two field assessment algorithms and a standardized pull-up test. Hazard of fiber emissions was assessed by a pull-up test method, whereas vulnerability was determined by a level of interaction between people and the rooftops. Geographic object-based image analysis was used to map hazard, vulnerability, and risk of asbestos rooftops in the study area. The field algorithms classified most rooftops in a bad state compared with the pull-up test which ranked most of them as good. The X-ray diffraction analysis showed the presence of serpentine and amphibole fibers, except for crocidolite, in some rooftop samples. Hazard, vulnerability, and risk maps of the sampled area showed how hazard potential was amplified by vulnerability of population to possible fiber emission.

Desempenho termoenergético de coberturas vegetadas em clima subtropical

Este artigo apresenta o desempenho térmico de diferentes coberturas vegetadas aplicadas em um edifício de escritórios na cidade de Pelotas-RS, Zona Bioclimática Brasileira 2, observando, a partir do comportamento dos fechamentos opacos e transparentes, a contribuição das diferentes soluções vegetadas para o plano horizontal. O edifício condicionado artificialmente possui 187,50 m², configurando seis zonas térmicas, e foi simulado no software Energy Plus 8.4.0. Como alternativas às coberturas vegetadas – configuradas em quatro alturas de substrato – foram utilizados outros três modelos de cobertura: fibrocimento com laje de 10 cm em concreto – com e sem isolamento térmico de poliestireno extrudado – e fibrocimento com superfície externa pintada de branco. O estudo buscou determinar qual dessas coberturas é a mais eficiente energeticamente, através da avaliação dos resultados do consumo de energia e da análise do fluxo térmico no edifício. A cobertura vegetada de maior espessura de substrato (50 cm) apresentou melhor resultado, com consumo energético de 84,3 kWh/m2.ano. Já a cobertura de laje com telha de fibrocimento convencional foi responsável pelo maior dispêndio energético: 103,5 kWh/m2.ano. As coberturas vegetais apresentaram melhor desempenho que as demais em função das elevadas capacidade e resistência térmica e dos aspectos voltados a evapotranspiração e consequentes trocas de calor latente. Este trabalho almeja contribuir no melhor entendimento do desempenho termoenergético das coberturas vegetadas.

A meteorite impacted a house in San Carlos, Uruguay

Every year there are now almost two reports of meteorite falls that directly hit human beings or their belongings, which we call “damaging falls”. A new damaging fall occurred on September 18, 2015, when a meteorite impacted a house in the city of San Carlos (Maldonado, Uruguay). A 712 g stone broke through the asbestos cement roof and a wooden suspended ceiling. The meteorite and its fragments broke a wooden bed frame and a TV set. We conducted petrological and chemical analysis of the sample. The meteorite is classified as a LL6 chondritic breccia, with low content in siderophile minerals and moderate chondrule size. It has a shock stage S4 and a degree of weathering W0. This is the first Uruguayan meteorite to be confirmed. The prevalence of damaging falls is discussed.

Asbestos Exposure and the Mesothelioma Incidence in Poland.

Asbestos is carcinogenic to humans; the exposure to asbestos causes a wide range of diseases. Aim: Malignant mesothelioma (MM) is unique for asbestos exposure. Methods: Based on the physical inventory of asbestos-cement roofing, the social-economic situation of communes, the proximity of asbestos manufacturing plants, the land use data referring to the surface of the built-up area, and the historical data on the annexations, the amount of asbestos-containing products in use was estimated by computing best Random Forest models. Per capita asbestos use is an indicator to compare the state of asbestos use among countries. MM cases in the local administrative units (provinces) were tested by the application of Moran’s I and Getis and Ord statistic. Results: The total amount of asbestos roofing in Poland was estimated at 738,068,000 m2 (8.2 million tons). In total there were 28 plants in Poland located in 11 provinces throughout the country. The amount of asbestos-cement roofing in use is correlated primarily with the measurements of asbestos concentration fibers (rs = 0.597). MM raw morbidity rate was calculated, stratified by province, and classified into five groups with respect to incidence. Hotspots of MM cases are in the southern part of Poland. Conclusions: MM cases are concentrated in the same geographical areas, which may indicate an increasing impact of environmental exposure. The results of the local and global autocorrelation clearly indicate a statistically significant relationship between incidences of MM in provinces. Poland and other Eastern European countries are among countries with low MM incidence rate. Detailed investigation is desirable since the current MM morbidity rate in Poland seems to be underestimated.

Upgrading the glassy slag from waste disposal by thermal plasma treatment

The paper reports on the experimental results obtained from the production of glassy slag by the plasma smelting of a mixture of two different wastes. The combination of two wastes with different chemical compositions is a promising way to optimise the energy consumption in the disposal process. Asbestos-cement roof tiles (ACRTs) and fly ash from fluidised-bed boilers (with a weight ratio of 1:1) were used for the preparation of glassy (vitrified) slag. The thermal process facilitated a 14.4% reduction of the weight of the original mixture and a 72% volume reduction of the waste.The glassy slag is then adopted as a raw material in the production of porous materials intended for various architectural applications, thus eliminating the necessity for its further disposal. The formation of a porous glass-ceramic matrix, using the vitrified slag containing CaSO4 as the pore-forming agent, is described in detail. A glass-ceramic foam with 66% porosity is formed by the rapid heating of the mixture of glassy slag and a 1 wt% of CaSO4, consisting of crystallised calcium aluminosilicate (Ca2Al2SiO7, Ca0.88Al1.77Si2.23O8). The thermal conductivity of the prepared porous material, measured by a laser flash thermal analysis, is 0.22 W·m−1·K−1.

Estimation of the amount of asbestos-cement roofing in Poland

The unique set of physical and chemical properties has led to many industrial applications of asbestos worldwide; one of them was roof covering. Asbestos is harmful to human health, and therefore its use was legally forbidden. Since in Poland there is no adequate data on the amount of asbestos-cement roofing, the objective of this study was to estimate its quantity on the basis of physical inventory taking with the use of aerial imagery, and the application of selected statistical features. Data pre-processing and analysis was executed in R Statistical Environment v. 3.1.0. Best random forest models were computed; model explaining 72.9% of the variance was subsequently used to prepare the prediction map of the amount of asbestos-cement roofing in Poland. Variables defining the number of farms, number and age of buildings, and regional differences were crucial for the analysis. The total amount of asbestos roofing in Poland was estimated at 738,068,000 m2 (8.2m t). It is crucial for the landfill development programme, financial resources distribution, and application of monitoring policies.

New semi-automated mapping of asbestos cement roofs using rule-based object-based image analysis and Taguchi optimization technique from WorldView-2 images

ABSTRACTThe use of asbestos cement (AC) roofing materials is a significant concern because of their deleterious effects on human health and the environment. The main objective of this study was to map AC roofs from WorldView-2 (WV-2) images using object-based image analysis (OBIA). A robust Taguchi optimization technique was used to optimize segmentation parameters for WV-2 images in heterogeneous urban areas. In this research, two subsets of WV-2 satellite image sets were utilized to map AC roofs. Rule-based OBIA framework was developed on the first study area. Different supervised OBIA classifiers, such as Bayes, k-nearest neighbour (k-NN), support vector machine (SVM), and random forest (RF), were tested on the first image of the study areas to evaluate the performance of a rule-based classifier. Results of the supervised classifiers showed confusion between AC roof class and some urban features, with overall accuracies of 72.21%, 77%, 81.75%, and 82.02% for Bayes, k-NN, SVM, and RF, respectively. To assess the transferability of the proposed method, the adopted classification framework was applied to larger subsets of WV-2 of the second study area. The results of the proposed approach showed outstanding performance, with overall accuracies of 93.10% and 90.74% for the first and second classified images, respectively. The McNemar test emphasized the statistical reliability of rule-based result (in the first site) compared with supervised classification results. Therefore, the proposed framework of using rule-based classification and Taguchi optimization technique provide an efficient and expeditious approach to mapping and monitoring the presence of AC roofs and help local authorities in their decision-making strategies and policies.

Mapping asbestos-cement roofing with the use of APEX hyperspectral airborne imagery: Karpacz area, Poland – a case study

Abstract Asbestos and asbestos containing products are harmful to human health, and therefore its use has been legally forbidden in the EU. Since there is no adequate data on the amount of asbestos-cement roofing in Poland, the objective of this study was to map asbestos-cement roofing with the use of hyperspectral APEX data (288 bands at the spatial resolution of 2.7 m) in the Karpacz area (southwest Poland). A field survey constituted the basis for training and verification polygons in the classification process. A SAM classification method was performed with the following classification results: 62% producer’s accuracy, 73% user’s accuracy and an overall accuracy of 95%. The asbestos-cement roofing for buildings may be discriminated with a high classification accuracy with the use of hyperspectral imagery. The vast majority of the classified buildings were characterised by their small area (i.e. residential type buildings), which reduced the overall accuracy of the classification.

Determinants influencing the amount of asbestos-cement roofing in Poland

Abstract Because of its harmfulness to human health, asbestos has been banned in 55 countries, including the EU. In Poland, the use and production of asbestos and asbestos-containing products has been forbidden since 1997. However, there is no precise data about the amount of asbestos-containing products to be eliminated from the territory of Poland. This survey aims to identify characteristics that have a significant impact on the estimation of asbestos-containing products used in Poland. Statistical correlation between the results of the physical inventory count done in 155 municipalities was examined. As a result of the survey it was found that the amount of asbestos-cement roofing depends on the following factors: the number of individual farms in the village, the distance from the asbestos manufacturing plants, the age of the buildings and the economic situation of municipality. The results obtained may contribute to the ability to predict the amount of asbestos-containing products used in other municipalities.

Mapping of Asbestos Cement Roofs and Their Weathering Status Using Hyperspectral Aerial Images

The aims of this study were: (i) the mapping of asbestos cement roofs in an urban area; and (ii) the development of a spectral index related to the roof weathering status. Aerial images were collected through the Multispectral Infrared and Visible Imaging Spectrometer (MIVIS) sensor, which acquires data in 102 channels from the visible to the thermal infrared spectral range. An image based supervised classification was performed using the Spectral Angle Mapper (SAM) algorithm. The SAM was trained through a set of pixels selected on roofs of different materials. The map showed an average producer’s accuracy (PA) of 86% and a user’s accuracy (UA) of 89% for the asbestos cement class. A novel spectral index, the “Index of Surface Deterioration” (ISD), was defined based on measurements collected with a portable spectroradiometer on asbestos cement roofs that were characterized by different weathering statuses. The ISD was then calculated on the MIVIS images, allowing the distinction of two weathering classes (i.e., high and low). The asbestos cement map was handled in a Geographic Information System (GIS) in order to supply the municipalities with the cadastral references of each property having an asbestos cement roof. This tool can be purposed for municipalities as an aid to prioritize asbestos removal, based on roof weathering status.

Mapping asbestos-cement roofing with hyperspectral remote sensing over a large mountain region of the Italian Western Alps.

The World Health Organization estimates that 100 thousand people in the world die every year from asbestos-related cancers and more than 300 thousand European citizens are expected to die from asbestos-related mesothelioma by 2030. Both the European and the Italian legislations have banned the manufacture, importation, processing and distribution in commerce of asbestos-containing products and have recommended action plans for the safe removal of asbestos from public and private buildings. This paper describes the quantitative mapping of asbestos-cement covers over a large mountainous region of Italian Western Alps using the Multispectral Infrared and Visible Imaging Spectrometer sensor. A very large data set made up of 61 airborne transect strips covering 3263 km2 were processed to support the identification of buildings with asbestos-cement roofing, promoted by the Valle d'Aosta Autonomous Region with the support of the Regional Environmental Protection Agency. Results showed an overall mapping accuracy of 80%, in terms of asbestos-cement surface detected. The influence of topography on the classification's accuracy suggested that even in high relief landscapes, the spatial resolution of data is the major source of errors and the smaller asbestos-cement covers were not detected or misclassified.

Developing expeditious methodology for mapping asbestos-cement roof coverings over the territory of Lazio Region

This paper reports the results of a research activity over the territory of Lazio Region for the mapping of asbestos-cement (AC) roof coverings in conformance with Law D.M. 101/2003. Through combining data retrieved from Multispectral Infrared Visible Imaging Spectrometer (MIVIS) classification by Spectral Angle Mapper (SAM) and Regional Technical Map (RTM), it was possible to accurately map out the area of interest in reduced time. The maps acquired by applying the Minimum Bounding algorithm were then compared with the Classification and RTM Intersection. The results obtained so far were validated by means of field measurements and can be considered as satisfactory. However, we think it is necessary to highlight how combining MIVIS and RTM data, and using many different software packages, have contributed to give concrete answers to those environmental issues hardly to be investigated and, to open up new, significant prospects for territorial surveys.

TESTING ALGORITHMS FOR THE IDENTIFICATION OF ASBESTOS ROOFING BASED ON HYPERSPECTRAL DATA

There are several environmental issues in urban areas that are caused by the unintentional consequences of past activities. One of these issues is the wide application of asbestos cement in roofing materials in the 2 nd half of the 1900s. In this study, our goal was to identify different roof types and to determine those with asbestos components using high-ground (1 m) and spectral (126 bands) resolution airborne hyperspectral imagery (AISA Eagle II) and several classification approaches. In addition, we aimed to identify those wavelengths that play a significant role in distinguishing the different roof types. In the image analysis, the SAM, MLC and SVM classification methods were used to evaluate the different types of roofs. These methods resulted in accurate maps of the roof types, and asbestos cement roofs were identified with over 85% accuracy.

Methods for detection of asbestos-cement roofing sheets.

Methods for detection of asbestos-cement roofing sheets.

The Continuous Use of Asbestos in Ghana Despite Its Hazards (Case Study Area: Sekondi-Takoradi)

This paper reported on a research work conducted with the aims of investigating the regulatory position regarding the use of asbestos and also of assessing the evidence of the continuous use of asbestos cement products in the construction industries in Ghana, using Sekondi-Takoradi as a case study area. This paper adopted both quantitative and qualitative research approach to seek information from, landlords, and manufacturers of asbestos cement products, parliament and other Government Agencies. Data was obtained through questionnaire, interview and field work survey. In all, a total of 20 questionnaires were distributed. The research emerged that about 1200 housing units roofed with asbestos cement roofing sheet were constructed by the state owned construction company between 1976 and 2000 in the Sekondi-Takoradi Metropolis (about 12,000 nationwide), a period when the risk of asbestos was known in Ghana. The study in the newly developing areas in the Sekondi-Takoradi Metropolis indicated that, out of every 100 housing unit being built, at least 40 of these were roofed with asbestos cement corrugated roofing sheet. It was also emerged from this research that there were no laws prohibiting the use, manufacturing or importation of asbestos products in Ghana. And this exposes maintenance workers in the building construction industries to the risk of asbestos related diseases. The research recommended that those who have asbestos materials present in their premises should take action to manage the risk so that no one will unknowingly disturb it and also provide information about the material to those who are likely to disturb it.

Methodologies to identify asbestos-cement roofing by remote data

Methodologies to identify asbestos-cement roofing by remote data