Asbestos is often mistaken as one substance. In fact, it is a term of a number of different fibers with different properties. There are two distinctly different fibers: the serpentines, chrysotile, and the amphiboles, all the others.
Chrysotile is distinctly different from amphiboles, which can be told if magnified under microscope. Chrysotile is seen white and curly while amphiboles are seen needle-like. According to increasing evidence, the curly nature can help the human body to remove chrysotile fibers from the lung. However, needle-like fibers inhaled will never be removed from the body. Generally speaking, chrysotile is safer than amphiboles, such as amosite and crocidolite.
The ceiling should be made of chrysotile which is always made into asbestos cement sheet, for it can be spun and woven into fabric. If the ceiling is in good condition, it will not release huge quantities of fibers into the air. The ceiling should only be removed if it is disturbed or in bad condition.
As said in the first question, asbestos have a large family. One member of this family, chrysotile will do no harm to human being's health if it is in good condition. Owing to its flexible structure, it can be spun and woven into fabrics and made into many products. Asbestos cement sheet accounts for a small part of chrysotile products.
At the same time, we should know that asbestos cement sheet contains only 10% ~ 15% asbestos. Even if the asbestos cement sheet is in bad condition, the quantity of asbestos released into air is much less.
Although asbestos cement products contains only 10% ~15% asbestos, these products still should be paid enough attention to their potential risks of causing severe disease. If done as the precautions below, it is unlikely that the concentration will be higher than the limited value.
Workers should be warned that they are working with asbestos products which will cause health problems. Keep the asbestos cement products wet while working on it. When asbestos cement products are cut or drilled, make sure they are wet and operated in the open air.
Workers should were a disposable mask and overalls. All these stuff should be disposed of at the end of the shift as asbestos waste.
When worked on the asbestos cement products, power tools should be avoided for prevent asbestos fiber releasing in the air.
Keep the spot clean and tidy all the time. Asbestos products should be carefully placed in polythene bag.