As the number of illegal methaphetamine laboratories continues to increase, the Government has put out a new set of guidelines to help people clean up the toxic mess left behind at P-lab houses.
The Ministry of Health says there has been a dramatic increase in the discovery of P-labs - from nine in 2000 to 135 last year.
It says the guidelines provide useful information about what the different chemicals are and what the risks might be.
A manager of environmental health at the ministry, Sally Gilbert, says the guidelines should provide practical advice for anyone who may suspect they have bought or are living in a former P-lab.
There is, however, no specific information about how to clean the houses, because that is a specialist job.
The founder of the drug education group Methcon, Mike Sabin, says the guidelines do not go far enough: in his view, they should have set specific standards so that the clean-ups can be done properly.
