The removal of paint films containing lead-based paint can result in harm to the person doing the job and the people who live or work nearby. Children, especially preschoolers, are particularly at risk. Untreated lead poisoning even can lead to brain damage or even death. Therefore it is important prior to removing old paint to know if the existing paint is lead based and, if so, to take appropriate precautionary measures.
How to test for lead-based paint
It's not possible to tell lead-based paints by their appearance, but there is a simple test that can detect whether the paint is a health risk. If you are unsure, 3M Lead Check Test kits are available for purchase from any Dulux trade outlet.
If a building is over 25 years old, it is best to presume that it has been painted with lead-based paint.
There is an excellent Ministry of Health document which covers the specific practices contractors and building owners/landlords should follow when dealing with lead-based paints. Dulux trade centres and depots have hard copies of these as well as it being available online. I strongly recommend painters become familiar with it.