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WHITE PAPER - FEB 2026

Updated: Mar 11


UK Centre for Mould Safety Calls for New Public Health Guidelines on the

Safe Removal of Indoor Microbial Contamination and

Updated Guidance on Biocide Use

Executive Summary (2-minute read)

Indoor Air Aware, trading as the UK Centre for Mould Safety (UKCMS), has published this paper to inform new UK public health guidance on the safe removal of indoor mould and the use of biocide products in homes and buildings.

The report was developed in response to growing evidence that widely used “mould-killing” chemical sprays and fogging systems are not necessary for effective mould remediation and may introduce avoidable health risks.

International guidance is already shifting. The 2024 German Environment Agency guidelines, developed by 36 scientific and medical experts, state clearly that biocides are “not necessary, nor effective” for mould remediation and are used far too frequently in practice. The report explains that even when biocides temporarily reduce mould counts, contamination commonly returns within weeks because the underlying problem—moisture and contaminated materials—has not been removed.

This position aligns with guidance from the US Environmental Protection Agency, the New Zealand Institute of Environmental Science and Research, and the internationally recognised ANSI/IICRC S520 professional mould remediation standard, all of which emphasise physical removal of mould contamination rather than chemical “killing.”

Mould contamination is a complex biological hazard. Exposure is not limited to spores; fragments, mycotoxins, β-glucans, and microbial volatile organic compounds can all affect health. Scientific studies show that disturbing mould can release hundreds of times more respirable fungal fragments than intact spores, meaning inappropriate treatment methods can actually increase inhalation exposure.

Effective remediation therefore focuses on removal, not poisoning the organism. Mechanical cleaning methods such as HEPA vacuuming and washing with water and household detergents (surfactants) can remove mould biomass without introducing additional toxic substances into indoor air.

Despite this evidence, the UK market continues to promote a large range of biocide-based sprays, washes, and fogging treatments that claim to “kill,” “remove,” or “prevent” mould. These products are widely used in homes, social housing maintenance contracts, and by remediation companies.

Safety Data Sheets for many of these products list hazards including respiratory irritation, asthma exacerbation, skin burns, eye damage, and environmental toxicity. Research has also linked exposure to cleaning and disinfectant chemicals with increased risk of occupational asthma and other respiratory illnesses.

Under the Control of Substances Hazardous to Health (COSHH) Regulations, UK law requires substitution with less hazardous substances where reasonably practicable. In the case of mould remediation, low-risk physical cleaning methods are available, raising questions about the routine use of chemical biocides indoors.

The UK Centre for Mould Safety is therefore calling for urgent public-health guidance clarifying that mould contamination should be removed through safe remediation practices rather than treated with unnecessary chemical products.

The organisation invites engagement from the Department of Health and Social Care, Department for Levelling Up, Housing and Communities, the Health and Safety Executive, UK Health Security Agency, Trading Standards, the Advertising Standards Authority, and other stakeholders to ensure that mould remediation practices in the UK are aligned with current scientific evidence and public-health protection.

_______________________ Introduction


This paper has been prepared by Indoor Air Aware t/a UK Centre for Mould Safety (UKCMS). Indoor Air Aware is a Community Interest Company created to protect public health. All content has been written based on factual information that is publicly available and has been referenced. The article intends to inform new public health guidelines on the safe removal of mould, and updated guidance on the use of biocide products on microbial contamination indoors. The founder of Indoor Air Aware and UKCMS, Lisa Malyon, created the free service and reference centre after collapsing and being rushed to hospital with pneumonia after repeatedly spraying ‘mould remover’ on mould growth inside during a period of 3 years. Lisa’s daughter, Phoebe, a toddler at the time, is now aged 10 and has since had severe breathing difficulties and requires a preventative steroid inhaler twice a day.  


Legal Correspondence


Manufacturer brand references have been omitted from this document following legal correspondence from manufactIntroduction

urers. A full body of product-specific evidence has been compiled to inform a formal enquiry.


New Guidelines Published


The 2024 ‘Guidelines on the Prevention, Detection and Remediation of Mould in Buildings’ published by the German Environment Agency explicitly states the use of biocides in mould remediation is 'not necessary, nor effective' and that ‘biocide applications (often mistakenly referred to as disinfectant measures) are in most cases inappropriate for mould remediation and are used far too frequently in practice’[1](P146). It also states: ‘Areas in the affected rooms must be carefully cleaned after removal of contaminated building materials. The use of biocides to kill microorganisms before the removal of contaminated building materials or cleaning and spraying biocides to treat the indoor air is not necessary’ (p146).


As a result, and in the interest of public health relating to indoor air quality, the UK Centre for Mould Safety (UKCMS) is calling for new public health guidelines on the safe removal of mould, and updated guidance on the use of biocide products advertised as being safe and suitable for use on microbial contamination (mould) inside homes or buildings. The 2024 German guideline, which was informed by 36 scientific and medical doctors and professors, explains that ‘scientific studies on biocide use for mould prove that it has no effects at all, or no lasting effects can be achieved by biocide treatment under practical conditions in most cases.’ It explains that ‘even if the concentration of cultivable moulds was reduced by the biocide treatment, high mould fungus concentrations reappeared on/in the material a few weeks later.’ (p149)


The latest German Environment Agency guidelines also states: ‘Biocides are not required to be used in deep cleaning since mould constituents are removed mechanically by vacuuming or wiping.’ (p146)


The new report confirms the guidance already published by the New Zealand Environment Agency[2], US Environmental Protection Agency[3] and the recently adopted national standard of mould remediation in Australia - the American National Standards Institute (ANSI) / Institute of Inspection, Cleaning, and Restoration Certification (IICRC) S520[4] - the ‘Standard for Professional Mold (sic) Remediation 2025’. The UK Centre for Mould Safety is underpinned by this safe standard of mould removal.[5]


Mould Must Be Removed, Not Killed 


In the interest of reducing indoor contamination, mould must be removed in its largest form. All parts of mould growth are hazardous, not only spores. Fragments, hyphae, mycotoxins, β-glucans, and microbial volatile organic compounds (MVOCs) can all affect health, whether growth is active, dormant, or desiccated. 


There are multiple peer-reviewed studies in leading journals demonstrating that physical disturbance of mould can generate large numbers of fungal fragments, which are smaller than spores and more readily respirable. Experimental studies show that fungal fragments released during disturbance (killing) can outnumber viable spores by up to 320 times, substantially increasing inhalation exposure. These fragments remain biologically active and can penetrate deeper into the respiratory tract than intact spores.[6]


Liquid Soap Use in Mould Removal


Moulds are eukaryotic organisms whose cells are enclosed by a phospholipid bilayer membrane containing embedded proteins. Surfactants act on such membranes by disrupting lipid-lipid and lipid-protein interactions, leading to solubilisation of membrane lipids through micelle formation.[7] 


This mechanism is well established in cell biology and is routinely exploited in laboratory settings to lyse eukaryotic cells and solubilise cellular membranes for biochemical analysis.


The same physical principles explain why surfactant-based cleaning enables the effective removal of mould material from surfaces without reliance on chemical toxicity.[8]


The most recent German Guidelines state (P128):


Smooth surfaces: It is sufficient to wash off smooth surfaces (tiles, ceramics, glass, metal and tile joints) using water and household cleaner to remove infestation, contaminated dust or dirt. The water should be changed frequently to prevent uncontrolled spreading or smearing. Silicon joints in the bathroom noticeably infested with mould should be replaced because they cannot normally be cleaned.


Porous surfaces: Plastered or painted walls can be wiped with an alcoholic cleaner containing 70% to 80% alcohol* or a common household detergent (not vinegar) using a microfibre cloth. Before that, one can hoover using a commercially available vacuum cleaner equipped with an additional filter (HEPA filter) and an airtight housing. Vacuum cleaner bags can be disposed of in the household waste.

*See below section ‘Health and Safety Law – Substance Substitution’ which would require the lowest risk substance – in this case a household detergent (liquid soap) over alcohol, which comes with fire and explosion risk, as well as impacting air quality through evaporation.

Chemical Use on Mould – Status Quo

Since the 1980s biocide-based chemical cleaning and decorating products have been advertised to tradespeople and households in the UK to 'kill mould', 'remove mould' or 'prevent mould'.

Cleaning mould with biocides was normalised by the vast choice and availability of products in supermarkets, hardware stores and trades merchants - this is manufactured demand cultivated through product proliferation, shelf space, marketing language, and social norms. When retail outlets offer multiple mould sprays, the brain concludes that mould is a problem with a chemical answer. More latterly, ‘trusted’ social influencers with millions of viewers have been paid to attend sales stands and feature in paid adverts while laughing, joking and dancing with a person dressed as a giant bottle of mould spray. Social Housing 'Schedule of Rates' Specification In the UK there are approximately four million households whose properties are owned by councils or housing associations. Procurement teams overseeing works carried out in these homes rely on the 'schedule of rates', which lists biocide products as the default product for use on mould. Search 'schedule of rates' for more information.


Health and Safety Law – Substance Substitution


The UK Health and Safety Executive (HSE) make clear that under the Control of Substances Hazardous to Health (COSHH) Regulations 2002, employers must prevent exposure to hazardous substances where reasonably practicable, and that ‘substitution with a less hazardous substance is one of the primary ways to do that’. The official guidance states that you should substitute with another substance which presents less, or no, risk if possible as part of preventing exposure to a hazardous substance.[9]


This duty applies to any employer, landlord, managing agent, contractor, or organisation that uses, specifies, supplies, or requires the use of chemicals as part of work activities in homes or buildings. These duties apply both to employees and other persons. 


Health Impact Tested on Live Dogs


Didecyldimethylammonium chloride (DDAC) is a quaternary ammonium compound (a substance often referred to as a ‘quat’) widely used in mould sprays, disinfectants, fungicides, and surface treatments. In regulatory toxicology, DDAC was subjected to repeat-dose oral toxicity studies in dogs (typically beagles) for 90 consecutive days to establish the 'No Observed Adverse Effect Levels' (NOAEL) safety threshold. These studies recorded systemic effects at relatively low doses, with female dogs often showing adverse effects at lower exposure levels than males - a point that matters when extrapolating to human health protection. There was no data on the effects of inhalation reported in this study.[10]  Impact of Indoor Biocide Use and Human Health

Pulmonologist Dr Olivier Vandenplas's 'Asthma related to cleaning agents: a clinical insight' study evidenced exposure to cleaning agents and/or disinfectant products used at work induced an asthmatic reaction in 39% of the participants who experienced asthma symptoms on exposure to these products.[11] 

See appendix for a further 10 research papers related to workplace illness associated with cleaning products.

Disparity Between Safety Data Sheets and Product Labelling

Safety Data Sheets for biocide washes, sprays and fogging solutions repeatedly flag a very consistent set of human health hazards, typically:

  • Skin irritation and burns – may cause redness, dermatitis, or chemical burns after contact.

  • Serious eye damage – risk of eye irritation or permanent eye injury if splashed.

  • Respiratory irritation – vapours or aerosols can irritate the nose, throat, and lungs.

  • Asthma exacerbation – may trigger or worsen asthma and wheezing, especially in enclosed spaces.

  • Skin sensitisation – repeated exposure can lead to allergic skin reactions.

  • Harmful if inhaled – particularly during spraying or when used on large surface areas.

  • Harmful if swallowed – accidental ingestion risk, especially for children and pets.

  • Toxic to aquatic life – long-lasting environmental effects once washed down drains.

  • Corrosive effects (for chlorine or strong alkaline products) – can damage tissue and surfaces. 

Safety Data Sheets are explicit that these risks increase with poor ventilation, repeated use, higher concentrations, and vulnerable occupants. However, these products are often shown being used - even in the brands' own adverts and instructional videos - without ventilation, gloves, or eye protection. Under UK law (UK REACH + GB CLP Regulation[12]) the label must communicate the hazards identified in the Safety Data Sheet (SDS). This is often not the case. 

High Risk Application Instructions

Usage instructions printed on bottles of ‘mould spray’ often advise to spray directly at the area from 15-20 cm away. These instructions ignore the behaviour of the biological hazard being sprayed at.

A 2024 study ‘Correlating surface mold (sic) contamination with airborne pollution under mild indoor air disturbance: A case study of Aspergillus niger’ published in the Building and Environment Journal revealed that ‘a substantial amount of surface mold (sic) was aerosolized within 0.18 s under mild airflow disturbance, with source concentrations ranging from 1.1 × 105 to 1.5 × 105 CFU/m3 per disturbing airflow, and 30.4 %–85.2 % of the mold (sic) remained suspended for 10 min.’[13] 

A trigger spray creates more than a ‘mild airflow disturbance’, meaning the sporulation rate could be far higher causing even more indoor air contamination. Spraying a contaminated surface disturbs the mould colony, breaking fragile hyphae and releasing spores and respirable fungal fragments into the air, increasing inhalation exposure.

Health and Safety Executive Authorised Biocides

Upon application from product owners or importers, the UK Health and Safety Executive (HSE) authorise biocides for sale and use in the UK. Each product is assigned an individual HSE certificate number.

A manufacturer and retailer of biocide-based products advertised for mould remediation recently stated in a legal correspondence relating to health concerns relating to the use of biocides on mould indoors that UKCMS had raised: “The HSE certificate clearly endorses the safe use in relation to mould prevention and/or removal.”

Based on the scientific fact that biocides can only kill, not remove mould, this confirms the important role of the Health and Safety Executive in authorising biocides used in remediation practices that pose a risk to public health. 

Application of the Consumer Protection Act 1987 in UK Case Law

UK courts have consistently applied the section 3 test under the Consumer Protection Act[14]. The ‘Section 3 test’ under the Consumer Protection Act 1987 asks whether a product is as safe as people are generally entitled to expect, taking account of how it is presented and how it is foreseeably used in real-world conditions, not just whether it technically complies with regulations.

The following legal cases illustrate how those principles are applied in practice:

A v National Blood Authority [2001]

In A v National Blood Authority, the High Court held that blood contaminated with Hepatitis C was defective for the purposes of the Act, notwithstanding that no screening test was available at the time the blood was supplied. The Court determined defectiveness by reference to the level of safety the public was entitled to expect, rather than by reference to prevailing scientific knowledge or regulatory acceptance.

The case confirms that the existence of an unavoidable or unknown risk does not, of itself, preclude a finding of defect where the product, as supplied and used in practice, fails to meet legitimate safety expectations.

Wilkes v DePuy [2016] and Gee v DePuy [2018]

In Wilkes v DePuy and Gee v DePuy, the courts clarified that the assessment of defectiveness under the Act involves a contextual evaluation of risk and benefit, considering:

  • the magnitude and probability of the risk

  • the benefits provided by the product

  • the adequacy of warnings and instructions

  • the availability of alternative products or methods presenting a lower level of risk

These cases confirm that compliance with regulatory standards or accepted practice does not determine defectiveness. Where foreseeable risks exist and effective lower-risk alternatives are available, those factors are relevant to the court’s assessment under section.

Worsley v Tambrands [2000]

In Worsley v Tambrands, the Court considered the role of warnings in determining defectiveness. The judgment confirms that warnings may be relevant to the safety assessment, but only where they are clear, prominent, and consistent with the overall presentation of the product.

The case illustrates that warnings cannot neutralise or override marketing or presentation that conveys a higher level of safety or suitability for use. Where warnings are insufficiently prominent, or where they are inconsistent with the expectations created by marketing, they may not prevent a finding of defect.

Advertising Rules Under the GB Biocidal Products Regulation (UK BPR) 

The HSE UK Biocidal Products Regulation[15] prohibits biocide advertising that is misleading or that minimises health or environmental risks, including claims or imagery suggesting a product is harmless or safe by default. Every biocidal product marketed to the public must include this sentence (or a clearly visible equivalent): Use biocides safely. Always read the label and product information before use. Some sodium hypochlorite-based 'mould sprays' being sold in the UK are described by the product owner as biocides, but aren't classified as a biocide, creating further confusion for consumers.

Fogging biocides

 

Biocide solutions are also used by companies in ‘dry fogging’ or ‘fogging’ systems – a process that claims to ‘eradicate’, ‘kill’ or ‘remove’ mould. Biocides are added to a machine that an operative sprays around a home. UKCMS has recently been notified of one large fogging company advertising their biocide product as 'non-toxic', pet and family-safe, which is in breach of the UK Biocidal Products Regulation. UKCMS has been made aware of the growing number of cases of negative health outcomes considered to be directly caused by indoor biocide fogging activity. One impacted woman has incurable blood cancer. She explained to the fogging company that her consultant oncologist had asked her to confirm it was non-toxic, to which they replied reassuringly that the biocide fogging system was non-toxic. The company advertised the biocide fogging system as non-toxic, family- and pet-safe on the website until challenged by the UKCMS to change their claims.

The German Environment Agency guidelines refers to the nebulisation of biocides in mould remediation, stating: ‘In the case of remediation of microbial damage, biocide treatment is in principle not necessary because it is unsuitable for the proper removal of the biomass and the remediation of the cause of damage. The nebulisation of active ingredients in the indoor air, except for inaccessible cavities, is discouraged in any case.’ P151. 

UKCMS Call for Urgent Action Awaab’s Law has instigated positive attention to the health risks of indoor microbial contamination. However, the focus and tighter timelines have created a surge in ‘mould remediation’ companies offering a biocide ‘chemical wash and stain block’ service instead of safe removal procedures.  

For this reason, in the interest of protecting public health and homes, the UK Centre for Mould Safety is urgently calling for new guidance on the safe removal of mould and updated guidance on the use of biocides on indoor microbial contamination.

We welcome a response from all associated stakeholders:

·        Department for Health and Social Care

·        Department for Communities, Housing and Local Government

·        Health and Safety Executive

·        UK Health Security Agency

·        Trading Standards

·        Advertising Standards Agency

·        Industrial Injuries Advisory Council

·        British Retail Consortium

Contact

For more information, or to discuss the content, please email contact@ukcms.org

 

Appendix

 

Cleaning products and health impact – a selection of research papers

Archangelidi, O., Sathiyajit, S., Consonni, D., Jarvis, D. and De Matteis, S., 2021. Cleaning products and respiratory health outcomes in occupational cleaners: a systematic review and meta-analysis. Occupational and Environmental Medicine, 78(8), pp.604-617. 


De Matteis, S., Jarvis, D., Hutchings, S., Darnton, A., Fishwick, D., Sadhra, S., Rushton, L. and Cullinan, P., 2016. Occupations associated with COPD risk in the large population-based UK Biobank cohort study. Occupational and environmental medicine, 73(6), pp.378-384.


Drummond, M.B., Wise, R.A., John, M., T. Zvarich, M. and McGarvey, L.P., 2010. Accuracy of death certificates in COPD: analysis from the TORCH trial. COPD: Journal of Chronic Obstructive Pulmonary Disease, 7(3), pp.179-185.


Dumas, O., 2021. Cleaners and airway diseases. Current Opinion in Allergy and Clinical Immunology, 21(2), pp.101-109.


Dumas, O., Varraso, R., Boggs, K.M., Quinot, C., Zock, J.P., Henneberger, P.K., Speizer, F.E., Le Moual, N. and Camargo, C.A., 2019. Association of occupational exposure to disinfectants with incidence of chronic obstructive pulmonary disease among US female nurses. JAMA network open, 2(10), pp.e1913563-e1913563.


Fazen, L.E., Linde, B. and Redlich, C.A., 2020. Occupational lung diseases in the 21st century: the changing landscape and future challenges. Current opinion in pulmonary medicine, 26(2), pp.142-148.


Lavander, P., Meriläinen, M. and Turkki, L., 2016. Working time use and division of labour among nurses and health‐care workers in hospitals–a systematic review. Journal of Nursing Management, 24(8), pp.1027-1040.


Medina-Ramon, M., Zock, J.P., Kogevinas, M., Sunyer, J., Torralba, Y., Borrell, A., Burgos, F. and Anto, J.M., 2005. Asthma, chronic bronchitis, and exposure to irritant agents in occupational domestic cleaning: a nested case-control study. Occupational and environmental medicine, 62(9), pp.598-606.


Mekov, E., Nuñez, A., Sin, D.D., Ichinose, M., Rhee, C.K., Maselli, D.J., Coté, A., Suppli Ulrik, C., Maltais, F., Anzueto, A. and Miravitlles, M., 2021. Update on asthma–COPD overlap (ACO): a narrative review. International Journal of Chronic Obstructive Pulmonary Disease, pp.1783-1799.


Mirabelli, M.C., London, S.J., Charles, L.E., Pompeii, L.A. and Wagenknecht, L.E., 2012. Occupation and three-year incidence of respiratory symptoms and lung function decline: the ARIC Study. Respiratory research, 13(1), pp.1-9.

Romero Starke, K., Friedrich, S., Schubert, M., Kämpf, D., Girbig, M., Pretzsch, A., Nienhaus, A. and Seidler, A., 2021. Are healthcare workers at an increased risk for obstructive respiratory diseases due to cleaning and disinfection agents? A systematic review and meta-analysis. International journal of environmental research and public health, 18(10), p.5159.


Van den Borre, L. and Deboosere, P., 2018. Health risks in the cleaning industry: a Belgian census-linked mortality study (1991–2011). International archives of occupational and environmental health, 91, pp.13-21. 


Xie, W., Dumas, O., Varraso, R., Boggs, K.M., Camargo, C.A. and Stokes, A.C., 2021. Association of occupational exposure to inhaled agents in operating rooms With incidence of chronic obstructive pulmonary disease Among US female nurses. JAMA network open, 4(9), pp.e2125749-e2125749. 


 

 

 

 

 
 
 

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