Dynamite
If you are going into building or renovations on a more than casual basis you really should do yourself a favour and have a good wander around Bunnings and look at the materials on display there.
Examine the timbers, plasters, glues etc, and while you're there, stock up on respirators, ear muffs and safety goggles, as well as gauntlet, waterproof and light weight gloves, disposable overalls and paper 'shower caps'.
From the tone of your posts today, you were really very worried, and yet you pulled the wall covering off and then broke a piece off the suspect material without knowing what it was.
Yes, there is plenty of asbestos around, also white tailed spiders, red backs, sharp rusty nails and toxic glues.
Did you know that MDF has been banned in most parts of America, as the glue gives off toxic fumes when hot (have you ever smelt that? It smells like a crematorium - scorching hooves & horns!!)
Harvey Industries has lots of information available on asbestos cement products. Asbestos has not been used since around 1985, and all cement sheet products since then have a manufacturers mark on them. Pre 1985 sheeting doesn't, and is a dull grey colour. A broken edge will clearly show the crocidolite crystal formation embedded in the cement. The crystals are very slender, clear, and are sharply pointed at both ends. They look as if they have shattered into fragments, and it is the sharpness which makes them so dangerous to lungs. The tiny shards become imbedded in the soft tissue and cannot be coughed out. Over time they may cause damage to alveolei causing bleeding and reduced lung capacity. Obviously, the ability of the lung to repair itself diminishes over time and asbestiosis or other lung disease may develop.
To avoid exposure to asbestos, only work on houses built since 1985. Every (very few exceptions - includes hospitals, kindergartens etc) building built prior to that will have asbestos lagging around hot water pipes, AC sheeting under the eaves, AC sheeting in the laundry, behind the hot water service, around damp proof courses, the faux brick covering of houses, roofing tiles, BBQ gloves, simmer mats for gas stoves, fire guards, and the original filters in cigarettes.
Asbestos has excellent fire rating, even when used in low %, and the content of asbestos was actually quite low in AC sheeting. Vinyl tiles and sheeting containing asbestos are virtually indestructable and much is still in very good condition today. It is the 'vinyl' part of the product which becomes brittle over time, and the adhesive and bonding matrix which smells when heated or burnt. Asbestos itself cannot burn, it is a crystalline material, is inert and has no smell.
Breathing protection should be used when working with older paints, too, particularly those made up until the early 1970s, as lead oxide was used extensively in paint, and can become air borne when sanding back.
But don't wear your old felt hat when working, as that will have been shaped useing mercury vapour, hence the saying 'mad as a hatter'.
And don't wear your favourite old fashioned watch, the radioactive fluorescent dial may affect your white cell count.
When sawing, sanding etc timber, MDF or cement sheet products, installing insulation or working with any product which releases dust (and that means everything), you should have your respirator on.
If we really want to keep health and safety risks in perspective, did you wash your hands with soap and water the last time you visited the toilet, and did you wash your hands with soap and water before you last ate anything or prepared any food in the kitchen? Or after you last patted your dog (and when was the dog last wormed?). Your are more likely to die from Hepatitis than asbestiosis.
Dynamite, I respect your concerns today but would invite you to consider that protecting our health and safety is an ongoing vigilance, not just when pulling the lining off the walls in old houses.
I wouldn't have a problem with AC sheeting - I've been working on two houses with significant quantities of the stuff, but I wouldn't take my chances by climbing onto a roof.
Sleep tight!
Kristine
PS no permit is required to remove small amounts of AC but disposal requirements are quite strict. No putting it out with the general garbage. The States workcover authorities and also the local munipalities have lots of information regarding removal.