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mould assessment


AARCO Environmental Solutions is an industry leading Class A Asbestos Licence Holder issued by WorkSafe WA, Environmental Consultancy, and a proud Supply Nation Certified company.


Exposure to damp / water damaged indoor environments is the main factor associated with many adverse health effects. In Australia, 1 in 3 homes are water damaged and have mould and costs hundreds of millions of dollars in repair bills every year. In the US, 1 in 2 homes are reported to have dampness and mould issues.

For the majority of healthy individuals, exposure to fungi/mould in an indoor environment would NOT NORMALLY cause any reactions of health effects. In most cases, occupants report a musty or damp odour and do not take much more notice that that, due to the natural defences of the human body.

However, for certain susceptible individuals such as those with impaired or immature immunological or respiratory systems, the very young or the elderly or individuals with predisposed genetic predisposition (CIRS), even SHORT-TERM LOW-LEVEL exposure to fungi/mould could lead to or worsen existing medical health conditions.

There are no recommended quantitative/numerical, health-based fungal/mould exposure guidelines or thresholds. Factors that determine health effects include the nature of the microbial growth, route of exposure and the susceptibility of the person(s) exposed. Due to these factors, it is not possible to determine “safe” or “unsafe” levels of exposure to microbial growth. The current approach is that any visible mould growth found indoors, regardless of the fungal species or amount of contamination, is inappropriate and should be managed/remediated/removed.


AARCO Environmental Solutions have qualified, industry-recognised and experienced investigators with local and interstate experience in assessing indoor environments (commercial, residential, industrial) for a wide range of industries including within government buildings, schools and educational facilities, worker accommodation units, and various office buildings.

Visual Assessment

mould assessment

Visual assessment of the impacts noting the extent of mould growth, water damage, stains and other potential signs of impacts (paint blistering, efflorescence, cracking, bulging etc).


  • Source of the water and/or moisture ingress.

  • Visible mould growth.

  • Presence of water staining to building materials.

  • Presence of moisture (condensation and / or dampness) to building materials.

  • Presence of dust and debris.

  • Pre-existing conditions (where possible).

  • Previous repairs and

  • Odours such as mould VOC odours (mVOC).

Sampling and Moisture Testing

moisture testing and sampling

If visible mould is not detected after a thorough inspection but is suspected, microbial air and surface sampling in combination with moisture measurements from affected building materials may be carried out to determine the potential level of exposure and to determine the nature of the contamination. In doing so, potential ‘hidden’ sources such as behind walls or in cavities may also be determined.

  • Non-viable airborne samples are collected using Air-O-Cell sampling cassettes coupled to a Bio-pump. Air-O-cells contain a gel covered plate which is examined under microscope to directly determine the quantity of fungi collected on the gel media. Identification of fungi is on the basis of spore characteristics and is generally considered accurate to genera level.

  • Non-viable surface samples are collected using Bio-Tapes; a flexible plastic slide with a covered adhesive portion, which is examined under microscope to directly determine the quantity of fungi collected on the adhesive portion of the plate.

  • After collection samples are sent under chain of custody procedures to a NATA accredited laboratory for analysis.

  • Additionally, an ATP Meter may be used to determine the Hygiene status of the contaminated surfaces by providing an instantaneous reading, with the unit providing a result in Relative Light Units (RLU). The adopted criteria of 60 RLU is used to indicate the status of cleanliness. Levels below 60 RLU are considered clean and above 60 RLU warrant further investigation. 

  • Moisture measurements are undertaken of building materials (floors, walls and ceiling) using a Protimeter MMS2/FLIR MR277 moisture meter and Tramex Moisture Encounter Plus meter. Moisture readings above 15% WME generally indicate an elevated moisture reading and should be further investigated.

  • Relative humidity, temperature, dew point and absolute humidity readings within the Impacted Area are collected to locate indoor areas that may have elevated humidity and contribute to elevated moisture within the building, which can potentially support mould growth.

Risk Assessment and Remedial Action Plan

mould risk assessment and remedial action plan

Following the visual assessment and gathering of quantitative data (moisture testing, air quality parameters, air and surface samples), a risk assessment is conducted to determine if area restrictions are warranted for the impacted area and the development of an action plan for remediation.


  • A number of guidelines have been adopted to determine whether the occurrence of mould in any particular setting the air could be considered unusually elevated or high. Often consideration is given to the wider context of observational data, evidence of dampness, background concentrations; usually obtained from duplicate outdoor reference samples, mould / spore concentrations indoors and benchmark concentrations bands. 

  • The term “normal” is used within the adopted mould guidelines to indicate fungi concentration and distribution similar to outdoor air and conditions at the time of sampling. As such in a scenario where indoor and outdoor concentration are similar but the distribution of fungal genera is dissimilar may not be considered normal.

  • The IICRC S520 – Standard and Reference Guide for Professional Mold Remediation defines surface mould contamination as follows:

    • Condition 1 (Normal fungal ecology): an indoor environment that may have settled spores, fungal fragments or traces of actual growth whose identity, location, and quantity are reflective of a normal fungal ecology for a similar indoor environment. 

    • Condition 2 (Settled spores or fungal fragments): an indoor environment which is primarily contaminated with settled spores or fungal fragments that were dispersed directly or indirectly from a Condition 3 area, and which may have traces of actual growth. 

    • Condition 3 (Actual growth): an indoor environment contaminated with the presence of actual mould growth, associated spores, and fungal fragments. Actual growth includes growth that is active or dormant, visible or hidden.


AARCO Environmental Solutions have qualified, industry-recognised and experienced assessors with local and interstate experience in the development of mould remediation action plans for a wide range of projects from simple single room localised mould and water damage impacts to widespread whole building water inundation/flood events.

Post Remediation Verification

post remediation verification or PRV

Following the completion of remedial works, the performance of a Post Remediation Verification (PRV) Assessment is essential in determining the effectiveness of remediation actions. 


  • All visible mould damaged has been removed.

  • All contaminated material has been removed and the area is left dry, clean and free of mould, debris and dusts.

  • The original cause of the moisture ingress has been eliminated and water issues repaired.

  • No mouldy odours remain.

  • Moisture impacts on building materials has been rectified of completely removed.

  • If air and surface samples are collected, that Condition 1 (normal mould ecology) has been established for the indoor environment.

AARCO Environmental Solutions have qualified, industry-recognised and experienced investigators and assessors with local and interstate experience in the performance of PRV / clearance assessments for a wide variety of clients including for insurance, builders, Work Health and Safety representatives, government departments and residential clients. 

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