Why is Methamphetamine Decontamination Necessary?
The process of manufacturing and using methamphetamine in a home result in the generation of aerosols that can potentially spread throughout a home and deposit (and can be absorbed) as a residue on hard and soft surfaces. Without any site remediation, these residues will remain long after manufacturing or use has ceased, which in turn may result in exposures and cause potentially adverse health effects to individuals who enter the premises or later re-occupy the premises.
Small amounts of methamphetamine exposure can cause:
- irritation of eyes
- breathing difficulties
- irregular or rapid heartbeat
- increased body temperature
Potential adverse health effects associated with higher levels of exposure to residues produced in the manufacture and use of methamphetamine include:
Neurochemical changes in areas of the brain that are associated with learning, potentially affecting:
- cognitive function
- motor activity
- changes in avoidance responses 
Physiological and behavioral/developmental effects that include:
- violent behavior
- mood swings
- paranoid behavior
- sleep disorders that are associated with the exposure. 
Methamphetamine Contamination in Australia
Over the past 5yrs (2016) there have been 3552 clandestine laboratories detected in Australia, using the analogy that only 1 in 10 is being found there are possibly 31,968 undetected clandestine laboratories within our communities. Around 70% (22,378) of which, are in residential homes, and are continuing to harbor methamphetamine and precursor residues, and emit poisonous gases many years after manufacturing and use have ceased. 
As a reasonably conservative estimate which assumes methamphetamine manufacturing and use has been part of our society for approximately 20 years, assuming that the number of labs and the number of users has been fairly consistent over that time there would be over 90,000 dwellings that are possibly contaminated from clandestine laboratories alone.
Australia has one of the highest rates of illicit methamphetamine use in the world and the highest use among English-speaking countries. Around 2.1% of Australians over the age of 14 years – around half a million people – have used methamphetamine in the last year (2013). This rate is three to five times higher than the USA, Canada (0.5%) or the UK (1%). 
Meth users can contaminate multiple properties per year. As another reasonable conservative estimate, if each clandestine laboratory supported 10 users and each user contaminated just 1 property per year the number of sites contaminated over 20 years would be over 900,000 dwellings.
The USA is said to have nearly 10% of its homes, apartments, and dwellings where people live with some sort of methamphetamine contamination from production or use. This above estimate of 900,000 dwellings with some sort of methamphetamine contamination is in line with estimates of contaminated dwellings in the USA, in that 900,000 is just under 10% of Australia’s 9,924,844 dwellings (2016). 
Property Owners Responsibility
Under Australian laws, the property owner is ultimately responsible to ensure a premise is safe for habitation. After the discovery of methamphetamine contamination in a property above 0.5μg/100cm², decontamination cleaning is required to remove hazardous levels of methamphetamine, after which an independent test should be completed to confirm that decontamination has been successful. 
Even though Australian law requires remediation of homes where methamphetamine testing finds more than 0.5μg/100cm², because there are no methamphetamine contamination disclosure laws in Australia, these undetected clandestine laboratories and contaminated user sites are often being given a quick makeover before being sold or leased to the unsuspecting purchaser or tenant.
Approximately 10-20% of methamphetamine contaminated dwellings are identified as, or suspected to have been former clandestine laboratories. Contaminated dwellings that are identified as, or suspected to have been, a former clandestine laboratory should be reported to the appropriate authority, usually a local council Environmental Health Officer (EHO). The local Council EHO may issue, a Pollution Control/Prohibition Order or other Environmental Order against the property (and owner).
The Pollution Control/Prohibition Order cannot be removed until independent clearance testing confirms that methamphetamine decontamination has been successful and that residues are below the 0.5μg/100cm², threshold and the property is safe for habitation.
Where the site has been identified as or suspected to have been a former clandestine laboratory additional testing and reporting may be required. Under the Australian Clandestine Drug Laboratory Remediation Guidelines, former clan labs require an environmental hygienist to be engaged.