Residue Testing NZ – P Contamination testing company in Auckland
Often we are asked to retest a property when other companies or individuals have been through and submitted a test result. Most often there is a variation between our result and others. There are a number of reasons why this happens:
- Not all tests are created equal – Some testers use composite testing techniques that are designed to cut costs but if they give you a meth level number as a result of such a test it should be taken extremely lightly.
- Not all testers are created equal – Over the years we have observed some crazy sampling practices like swabbing floors, ceiling fans and range-hoods. These methods are focussed on hunting down residue concentrations which are not reasonable representations of the area as a whole. We DO NOT do this as these practices just serve to alarm the clients in the end.
- The basic standard (developed by NIOSH – National Institute for Occupational Safety and Health in the USA) is to sample 100cm² in each area. If you can imagine that we have no way of knowing exactly where the residue has collected because it can’t be seen, we can only take a representative sample. Obviously a few metres to the right or left of that sample the residue will be of a slightly different concentration. The main point is that we are taking a REPRESENTATIVE SAMPLE only in each area.
- Some surfaces will present higher values – We know that varnish and polyurethanes seem to have higher concentrations when tested. If a room is fully wood panelled then this might be a fair representation but if your tester goes straight to the only bit of varnish in a room then he/she may be trying to ramp-up the result. Of course in a freshly painted room sometimes you have to test the varnished doors to get any result at all.
The bottom line is a screening test of any kind is just that, it should give you a clear positive/negative result. If in the event of a positive test the client chooses to commission a multiple sample laboratory test, the testers should focus on fair representative samples to give the client a broad picture of the extent of contamination. Should a second set of tests be commissioned, we would expect a spread of results that roughly reflect the levels of the first but we would never see an identical set of results.
Our testers are skilled at interpreting testing methods and results so if in doubt contact your local franchisee.
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