What is so important about asbestos-cement?

Over 95% of the Chrysotile asbestos fiber mined worldwide is mixed with cement to form roofing, siding, pipes and many more products. These products have been used for decades throughout the world, but due to bans on their use in many countries they are now marketed primarily in developing countries.

Is asbestos roofing sheet or exposed asbestos pipe rendered harmless by painting it over?

Painting over the sheets or the insulation (e.g., when wrapped around pipes) is not a method of encapsulation.  The paint may seal the product somewhat, but it may not prevent it from becoming friable (broken into smaller pieces). And when the paint becomes old and peals away it takes an asbestos layer with it which is brittle and breaks and asbestos particles becomes airborne.   In addition, the ‘act’ of painting or trying to encapsulate the asbestos by other methods may loosen asbestos fibres which then can become air borne.

See http://www.ccohs.ca/oshanswers/chemicals/asbestos/home.html#_1_7

How can I test if a building material has asbestos?

Do a web search and contact an asbestos testing laboratories that are certified for bulk asbestos sample analysis. Here is a partial list for India:

Elca Laboratories   www.elcalabs.com

How can I test if the air in my home is safe from asbestos?

As the minimum contaminant level (MCL) for airborne asbestos fibre is zero and as old homes in countries with cold winters usually contain asbestos materials, it is likely that the air inside such homes has asbestos. This is less of a problem for homes in countries with warm climate unless the home has asbestos roofing. Do a web search for asbestos testing laboratories that test air for asbestos.  For example, www.emsl.com