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The controlled and responsible use of chrysotile asbestos, as applied in Brazil, ensures total control of mineral fiber emission in the air, during mineral extraction processes, production and application of materials that use asbestos as raw material. Controlled use also includes continuous analyses, inspection and supervision done by the company, by the worker and by the government. It also includes all the agreements signed by and among these parties.
The Tripartite Agreement, ratified by representatives from the government, the workers and employers, from the Cana Brava mine and from the fiber cement factories, resulted in strict laws, advanced joint agreements and efficient and high-tech control measures.
The following will give you an idea of how the evaluation of the workplace is performed and what the safety measures adopted by the industries are:
Evaluating the work environment: an indispensable measure within the context of the controlled use of chrysotile asbestos.
Strict follow up of the number of fibers per cubic centimeter makes it possible to:
- learn about the fiber content and concentration in the work environment;
- conduct an evaluation of the working conditions;
- conduct an evaluation of the efficiency of the powder removal system already in place, and the control measures that have been implemented;
- detect any anomalies in the system, thereby enabling preventive maintenance.
This is how air is collected:
In the case of chrysotile asbestos, the air in the workplace is collected with the help of special suction pumps fitted with membrane filters. A microscope set for 500 x magnification is used for the analysis. The results are expressed in fibers per unit of volume of air - in Brazil, the adopted unit is f/cm3 (fibers per cubic centimeter).
Outside the work area, fiber evaluation in the environment is done by means of different and very complex techniques, because the concentrations are significantly smaller. They are expressed in fibers/liter of air, which corresponds to the thousandth part of the concentration adopted at the occupational level.
Measures adopted by industries where chrysotile asbestos is used as raw material:
Powder Removal: a complex set of measures adopted to control dust where it is generated. It involves cowls, piping, process damping, ventilators and filters.
Sealed booth for cutting chrysotile asbestos shingles: the cutting operation of fiber cement shingles is done in a sealed compartment and the operator is not exposed to any dust whatsoever. Usage guidelines are posted near the panel, in a visible place.
Waste recycling mill in chrysotile asbestos fiber cement plants: all the fiber cement residues return to the productive process, in the so-called "zero residue cycle". This way, residues are recovered and totally recycled.
Individual protection and training programs: workers are made aware of the risks inherent to the operation and the control measures that should be taken. Operators learn how to use adequate protection equipment, as needed, such as respiratory protective equipment (RPE) or dust masks and uniforms.
Storage and distribution: chrysotile asbestos is packaged at the mining site in resistant plastic bags. The bags are placed on pallets and then covered with shrink-wrapped plastic for further protection. This procedure makes it easier for lift trucks and pallet trucks to handle the packages. Most companies and all the fiber cement industries incorporate the plastic bags used to package asbestos to their products, as raw material.
Cleaning industrial facilities: a wet or vacuum process can be used to clean structures and machinery and the cleaning process includes portable vacuum cleaners or flexible hoses, connected to the central exhaust system. Industrial surfaces are cleaned by means of mechanical sweepers, in order to prevent dust from being generated. A customized cleaning program, catering to the needs of each plant and plant sector, will serve as the guide for the type of equipment that should be used, the ideal interval between scheduled cleanings, and who should be responsible for the operation.
Moulding small parts (roof ridges) of fiber cement with chrysotile asbestos: a wet process is used in this operation. Cutting over trays prevents the floor from becoming dirty.
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