Asbestos is a number of artificial minerals created in mass quantities for purposes such as temporary insulation, chemical and thermal heating cushions for household uses.
Asbestos is commonly used as an insulator for airconditioning vents, and many other insulating materials. Many products are in use today that contain asbestos.
If your house was built before 1990, there is an 86% chance that your air-conditioning vents are asbestos-based. Asbestos is known to create severe breathing problems. 61% of households that have asbestos-based vents are treated for acute asthma, and 37% of those people are being treated for Mesothelioma, a form of cancer that is almost always caused by previous exposure to asbestos
When asbestos is heated, it stretches out into a layer of dust and dissolves into the air of the vent. The dissolved asbestos is a light-weight, flamible material. These conditinos allow asbestos to be a very dangerous material, but it was still used by many construction companies because of the cheap price it held in the market.
Asbestos is a hazardous material when it becomes friable – meaning that asbestos is easily crumbled and reduced to powder by hand pressure, such as when it is disturbed or damaged. When asbestos is damaged or disturbed it releases fibers into the air. Airborne asbestos fibers are microscopic, odorless, and tasteless. Because asbestos fibers are small and light, they can be suspended in the air for long periods. People who live or work near asbestos related operations have a high chance of inhaling asbestos fibers that have been released into the air by work activities.
Once inhaled, the small, inert asbestos fibers can easily penetrate the body's defenses. They are deposited and retained in the airways and tissues of the lungs. In the alveoli, the location of gas exchange, asbestos causes the development of scar tissue - asbestosis. This thickening of the alveoli wall reduces the amount of oxygen available to the body leading to shortness of breath and chest pains. Asbestos is a known carcinogen that can cause lung and gastrointestinal cancers. Mesothelioma, a rare form of cancer affecting the outer membrane of the lung, heart, and abdominal cavity, is directly caused by asbestos exposure.
Here's where to look for asbestos and what to do if you find it:
Heating ductwork. Some ducts, particularly in Southern California, are made largely of asbestos; other metal ducts are wrapped with a cellulose-asbestos, air-cell insulation. Both look a bit like off-white corrugated cardboard; asbestos-sheeting insulation has a similar appearance but not the corrugations. In addition, registers may have asbestos taping inside.
Ductwork made of asbestos is a major concern because when it begins to deteriorate, fibers are blown into the house. Talk with an asbestos abatement contractor about removal.Replacement is additional.
Wrapped ducts should be removed if wrapping is friable. A stop-gap measure for duct wrapping that's sound is to have it encapsulated.
The furnace may have an asbestos lining at the base or sit on an asbestos pad. A special asbestos cloth may join furnace or boiler to ductwork. If any of these are exposed to damage, they should be encapsulated or removed.
To date, most research has centered around asbestos workers and their families, with whom it has been proven chronic breathing of asbestos fibers causes permanent scarring of the lungs (“asbestosis”), lung cancer and mesothelioma. Problems may show up 30 to 40 years after exposure.
A growing number of doctors and researchers are concerned about the long-term effects of low-level exposure.
As a rule, asbestos fibers tend to attach themselves permanently to lung tissue; long-term, residual accumulation might catch up with you. The prudent assumption, voiced by Lee Thomas, former Administrator of the EPA , is that there is “no safe exposure” to airborne asbestos
Why use flexible air ducts?
You may wonder why it is important to have insulated flex ducts in your home. Or, does this type of duct make a difference vs. standard ducting? The ducts listed in this section are UL181 listed, have an R-Value of 6 and come with a 10 year warranty. Why insulated duct? The insulation in the ducting will prevent condensation from forming on the duct. Condensation forming on the duct is not a good thing. Another benefit of the insulated flexible ducting is that it further reduces any “air noise” caused by the exhaust fan, so your ventilation system works even quieter.
Benefits of r-6
- It helps in your loss or gain of any heat in the ducts. In other words it helps in the utility consumption & your comfort. That is what you pay for in the unit's operation cost and the unit's capacity.
- For air conditioning it prevents the condensation or sweating than can occur from those ducts.
If leaks occur then loss of efficiency & / or sweating can happen. Also when wrap insulation is pulled too tight it to loses it's R value (it's insulating value). The higher R value the better is your insulation but a cost effective factor comes into play. It really isn't cost effective to increase to the extremes.
Usually insulation for ducts is R4 or R6 with the more common R6 being used in the insulation value. A formula used in insulation is: The actual attic air temperature minus the inside duct air temperature & then divide that result by 15. Ex: 125 degree in attic less 60 degree air inside ac duct = 65degrees then divide by 15 = R 4.3