This house has a central furnace for heating,and the hot air was piped to the rooms through big pipes insulated with asbestos covering. (House built in 1927.)
Asbestos fibers are carcinogenic. But the real estate lady said all you have to do is encapsulate the pipes, glue plastic covering over the surfaces.
That done, and the basement cleaned up. what about the crawl space?
That is, outside of the basement which only is under about 1/4 of the house, the pipes ran over the dry crumbled earth under the floors.
Do we need to assume that asbestos fibers have shed off the pipes over the years, and are mingled with the dirt? And if so, how would you deal with that (dig out the dirt; cover it with more dirt; …)?
Asbestos fibres are dangerous. If they lodge in the lungs and if they then cause cancerous growth, they can lead to asbestososis and mesotheliomia (sp?), both of which are particularly horrible ways to die.
However, the stuff is not likely to cause problems unless it’s in powder form and you breathe it in. Even then you’re pretty unlikely to have problems unless you’re dealing with pretty large volumes of the stuff. Millions of people handled asbestos and asbestos dust last century and only a relatively small percentage of those ended up with cancer.
Enclosing it in plastic is an effective way of dealing with the stuff on the pipes (but noting that won’t last forever).
An extremely small amount may have shed off the pipes and mixed with the dirt in your crawlspace over time. It is safer not to try to remove this stuff. If undisturbed it shouldn’t cause any problem. Ask yourself how many times you are likely to go into the crawlspace and whether you’re better off just leaving it alone.
If you’re really worried about it then cover it with some more dirt or with a layer of heavy plastic (eg garden plastic). When doing so, gently water the existing soil first (this will stop dust from being kicked up when you spread the new dirt around) then spread the new dirt or plastic over the area.
When doing this wear overalls and a proper respirator (such as those used by spraypainters, not just the cloth face mask). Shower yourself and wash the clothes you were wearing as soon as possible after finishing.
I spent the last two and a half years working for an asbestos abatement company, so allow me to put your fears to rest.
Asbestos is a naturally occuring substance – mineral fibre – which is mined directly from quarries and refined for all sorts of uses, particularly insulation such as you have described. Minute traces can be found in the air at any given time.
The scary part: Breathing asbestos fibres for a proplonged period of time (say 10 or more years) can result in lung cancer, mesothelioma, or asbestosis, all of which can kill you. However, the exposure must be very substantial. Further, the overall risk is only slightly higher than that of smoking.
The less scary part: When 'stos is bound up in a matrix, such as the insulating paper on your furnace pipes, the only way for fibres to escape is to seriously damage the material – if you went out and sanded the paper with a belt sander, you might have a problem. Short of that, it can be considered safe. So as far as your pipes are concerned in the crawl space, if you want to be extra careful, you can encapsulate 'em, as you did with the basement pipes, or, if they’re buried, just leave 'em alone. Undisturbed asbestos is safe asbestos, especially if it’s buried such that no one can get to it. There shouldn’t be a need to add or subtract dirt.