Asbestos is the name used for a group of natural minerals that are made up of many small fibres. These fibres are very strong and are highly resistant to heat, fire, chemicals, and wear due to friction.
In the past, the properties of asbestos made it popular for things, such as:
Asbestos was mainly imported and used before the 1980s. Once the health risks of asbestos were known, its use was gradually stopped and other materials used instead. However, products and appliances with asbestos content may still be around, particularly in homes built before 1984.
The most common types of asbestos fibre you are likely to find are:
Asbestos is a risk to health only when it is inhaled (breathed in) as fine dust. The risk to health increases with the number of fibres inhaled and with frequency of exposure.
When asbestos dust is inhaled, larger fibres tend to be cleared by protective mechanisms in the lungs and upper respiratory tract. The finer fibres are more difficult to remove, and may become deposited deep in the lungs, or penetrate further into the body. It is these fibres which can cause a number of diseases.
Small quantities of asbestos fibres are common in air, arising from natural sources (weathering of asbestos-containing materials), and windblown soil from hazardous waste sites, deterioration of automobile clutches and brakes, or breakdown of asbestos-containing materials.
The highest risk of exposure to asbestos in the home is through home renovation, by cutting or drilling through asbestos-cement sheeting or sanding down lino or tiles containing asbestos.
Generally, asbestos-containing materials that are in good condition will not release asbestos fibres. There is no danger unless fibres are released and inhaled into the lungs. The risk from exposure to asbestos in the non-occupational setting is considered to be low since the concentrations of asbestos fibres are low.
Exposure levels indoors depend on the asbestos type and its condition. Constant exposure to crumbly or powdery (friable), damaged, exposed, or poorly maintained asbestos materials may increase the health risk.
Testing a sample in an approved laboratory is the only way to find out if a material contains asbestos. If you need to get a sample tested, contact a health protection officer at Population Health. For cladding or flooring, a sample approximately the size of a $2 coin is required.
For decorative ceiling finishes, a minimum of one teaspoonful is required, and this should include any sparkly material. Samples should be obtained in accordance with Occupational Safety and Health Guidelines for the Management and Removal of Asbestos(external link).
Any samples you deliver or take to the health protection officer should be in a sealed envelope or in a zip-lock bag.
If there is asbestos or Asbestos Containing Material (ACM) confirmed by laboratory analysis in your home, you should talk with a health protection officer about:
External cladding should not cause any concern if not damaged. Even if the cladding is deteriorating, the Ministry of Health advises that the cladding should be sealed rather than removed or replaced. The process of removal will disturb the asbestos, where if left in place, the amount of fibres released is not considered to be a health risk. However, if you have asbestos-containing roofing, be aware that the ceiling space under the roof may have high concentrations of asbestos dust, particularly if the roofing is weathered and brittle.
Do not use powered tools or high-pressure water blasting on external cladding as this will release large amounts of fibres, which are a health risk when they dry.
The Ministry of Health strongly advises that you use Ministry of Business, Innovation and Employment certified contractors to remove ACMs as exposure to asbestos fibres is a danger to health. Necessary precautions and good work practices are well known to experienced specialist firms. They will also be better equipped to handle and manage disposal of asbestos and ACMs.
Names of certified contractors are listed in the Yellow Pages.
If you still intend to do the work yourself make sure you follow the advice in the Ministry of Health booklet Removing Asbestos From the Home(external link) available from Population Health. You can also read the New Zealand Guidelines for the Management and Removal of Asbestos(external link).