Physical Removal of Mould is Key

Current mould remediation guidelines state that physical removal of mould should be the normal course of action, and that use of chemicals to kill mould is NOT recommended. This is because of several reasons:
– Dead mould spores are still allergenic
– Dead mould spores and contaminated material still contains mycotoxins
– Use of chemicals on surfaces where mould growth is occurring does not remove the hyphae (think of hyphae as being similar to the roots of a tree) and the mould will likely continue growing afterwards.

Physical removal may be as simple as wiping off the mould on a surface. However, it is more likely that mould has grown into the material and wiping will only remove the surface layer. Ideally, contaminated material should be disposed of and replaced, however this is not always an option. It would be quite involved to remove and replace timber framework in a house for instance. Remediation of mould has to find a balance between complete removal of any contaminated material and the cost of the works to achieve this.

Normal Mould Remediation Practices

So how do really clean mould? In a typical remediation scope, several steps are followed:

First, temporary containment of contaminated areas is installed to minimise cross contamination of other areas. HEPA filtration and negative ventilation are also installed at this point to help prevent cross contamination and protect worker safety during works.

Second, if the underlying moisture problems have not been resolved, drying equipment will be installed.

Third, invasive works can begin. This primarily involves removal of contaminated plasterboard and thorough cleaning of timber framework through abrasive techniques (sanding, wire brushing, etc.) to remove the more contaminated surface layers. The timber framework will then be extensively vacuumed using an industrial HEPA vacuum. Any contaminated material must be bagged and sealed before removing it from the contained area or cross contamination will likely result. Additionally, damp wiping with clean microfibre cloth may be conducted in an effort to remove even more of the mould spores.

Fourth, every surface in the contaminated areas are cleaned multiple times, using HEPA vacuuming and damp wiping to remove as much of the mould as possible. Once the above work is completed the air filtration equipment is left to run for an additional period to remove any remaining airborne mould spores. Finally, new plasterboard and other materials are re-instated.

DIY Remediation and Protecting Yourself

Most home owners simply do not have the required equipment (such as temporary containment, HEPA filtration, drying equipment, moisture detection equipment and PPE) or expertise to complete mould remediation in a safe manner without cross contamination. Demolishing a mould damaged wall or ripping out mouldy carpet without containment measures and filtration in place will likely spread millions of mould spores throughout your home.

However, there are steps most people can take to minimise the risk to their health. Firstly, deal with any moisture issues promptly. If you have had a leak in your house it is highly recommended that you engage a professional to ensure the structure is actually dry. After leaks, wall bases and flooring often seems dry to the touch, but the inside of walls or under flooring is still saturated. Next, if you see mould growth starting to form, wipe it off immediately. While the problem is still present, this will help to limit the amount of mould spores released into the air, as mature colonies will release thousands of spores if left unchecked. Finally, try to keep your house as open and well ventilated as possible. While increasing ventilation will not solve the source issue, it will reduce your exposure through dilution of contaminants into the outside air.

Use of Chemicals

Bleach, vinegar, or whatever other chemical you use will at best kill the surface layers and leave a residue that mould can use a food source. The goal of cleaning should be to physically remove as much mould as possible, and to not leave any residue that mould can use as a further food source. Additionally, while bleach may kill surface mould it will also aid in hiding further growth so may be counterproductive in the long term.

In summary, physically remove as much mould as you can safely, don’t do invasive works without the proper measures in place, keep your house dry and stay safe doing so.