A chemist says new rules to help test and clean P-contaminated houses will deter meth testing cowboys, but it will not prevent the drug from getting into homes.
The new standards came into effect yesterday and limit contamination to 1.5 micrograms per 100cm squared for bedrooms, living areas, kitchens, sheds or garages.
That's up from 0.5 micrograms.
Massey University environmental chemist Nick Kim said the new standards applied only to properties where P had been smoked, not cooked.
"It's very much restricted to the procedures to use when you are testing a property or remediating a property and then writing reporting requirements around that
"It shouldn't be seen as a comprehensive standard to cover remediation of methamphetamine laboratories because they have a whole range of other chemicals, most of which are much more hazardous than the traces of meth."
Mr Kim said it was up to the government to prevent P from making its way into people's houses.