Vinegar vs Bleach

Mycologia is an advocate of using a naturally fermented white vinegar solution for mould remediation in the first instance. A vinegar solution is a better practical choice than a chlorine bleach solution or other disinfectants for routine mould clean-up for the following reasons:

  1. essentially non-toxic in the concentrations used; dilute vinegar solution is gentle on skin, safer for remediation workers than strong biocides and is safe around children.
  2. surfactant and an effective cleaning agent, and is very economical to use compared to other more expensive cleaning agents and biocides.
  3. slightly acidic, vinegar can dissolve mineral deposits from smooth surfaces, and vinegar solution rinses and dries residue free.
  4. safely disposed down the drain.

Chlorine bleach was formally generally perceived to be the solution for mould cleaning. Many well-intentioned recommendations by international and national health departments, and state and local government departments are still perpetuating this inaccurate belief.

Stop recommending the use of liquid chlorine bleach in routine mould remediation.

A Brief Guide to Mold, Moisture and Your Home (EPA 402-k-02-003) to exclude their once recommended use of  bleach as a mould clean-up agent.

Bleach exposure is known to exacerbate asthma symptoms in those who already have asthma and confirmed as causing new onset work related asthma (WRA) for those exposed to and using bleach at work.

In May 2012, the Association of Occupational and Environmental Clinics (AOEC) designated bleach (sodium hypochlorite) as an asthmagen, the term used for an asthma-causing substance.

The Research

The current scientific belief is vinegar may stimulate a nutrient cycle in the mould organism, which causes it to gorge itself and burst due to the rapid increase in internal osmotic (water) pressure. This osmotic effect is similar (but opposite) to the way that a 70% alcohol solution kills microorganisms.

The US FDA (Food and Drug Administration) concerning food treatment and preservation suggests the following:

The antimicrobial [and anti-fungal] action of organic acids [like vinegar] is due to pH reduction . . . disruption of [cell] membrane transport and/or permeability, anion [positively charged salt ions, eg, Na, K, Ca) accumulation, or a reduction in internal cellular pH by the dissociation of hydrogen ions from the acid.

Although fermented vinegar is primarily comprised of a solution of acetic acid in water, it also contains some tartaric, maleic and citric acids as well as other trace fermentation metabolites and compounds.

An interesting finding from Mycologia’s work has been that chemically produced “pure” acetic acid solutions are not as effective against mould as is distilled naturally fermented white vinegar. This is most likely due to the presence of these other organic acids and trace compounds from naturally fermented vinegar that are absent from pure dilute acetic acid.

The active ingredient in chlorine bleach is sodium hypochlorite, but otherwise it is mostly made up of water. A dilute chlorine bleach solution has been shown to be an effective sanitiser for bacteria, spores and viruses when used on clean, hard, non-porous surfaces. Studies suggest a 10% bleach concentration for killing mould.

Two common fungal species found in water damaged buildings, Chaetomium and Stachybotrys, propagate via spores and are unaffected by chlorine, acids, caustics or ozone. Chlorinating carbon-based organic toxins increases their toxicity by increasing their mutagenicity and their lipid solubility which allows these toxins to enter the skin and accumulate in the lipid rich tissues such as fat deposits and the brain. Reference:    McMahon et al., 2011. Common toxins in our homes, schools and workplaces. Global Indoor Health Network. 

Chlorine bleach is not effective for cleaning porous surfaces such as carpeting, ceilings; items made from wood and especially manufactured wood products (eg, MDF and chip board), gypsum-based wall board, etc. In addition, chlorine bleach may chemically damage, degrade, discolour or react with some materials.

From a mould remediation perspective therefore, the use of bleach is not recommended due to the following:

  1. short shelf-life and loses potency quickly, so the longer products sit on shelves, the lower their bleach concentration becomes. A product that starts out with a concentration of about four percent as stated on its packaging, by the end of its shelf life may contain just 0.6 percent bleach.
  2. neutral pH. When utilising bleach for cleaning mould in a bathroom, for example, the organic matter in the form of soap scum changes the pH of the bleach to a range that is ineffective for killing mould.  
  3. corrosive and this is clearly stated on product labels. The corrosive nature of bleach is harmful to grout and tiles as it erodes and corrodes the surfaces, making them more porous, thus making these surfaces more vulnerable to further penetration of fungal growth (hyphae).
  4. does not penetrate or soak into porous surfaces and the active ingredient sodium hypochlorite stays above the surface whilst water is absorbed into the porous surface. For this reason, bleach is ineffective in killing penetrated mould growth and therefore is not recommended for mould remediation of non-porous materials like gyprock drywall and wood.
  5. The colouring melanin, in fungi, is removed making it appear invisible. Proper remediation requires the removal of all mouldy material whether dead or alive, from the surface and that that has penetrated through porous material.

Health  Warning - Please Don't Mix Anything With Bleach

Do not mix chlorine bleach with other household cleaning agents. Doing so can cause serious harm to human health. For example, mixing chlorine bleach with cleaning products containing ammonia or acid (vinegar for example) releases Chlorinated Volatile Organic Compounds (CVOCs) like chloroformcarbon tetrachloridechlorine gas or chloramineswhich are highly toxic and may even be carcinogenic to humans.

Increases in new onset-work related asthma (WRA) due to bleach exposure in the work place has prompted the AOEC to designate bleach as an asthmagen. The AOEC carefully reviewed mandated reporting of work-related asthma as well as published toxicology and epidemiology peer-reviewed research prior to assigning the toxicity designation to bleach. The research data validated the need to promote asthma-safe, bleach–free disinfectants and sanitizers and promoting the consistent use of personal protective equipment when handling chemicals.

In the aftermath of a flood, the US Center for Disease Control and Prevention (CDC) guidelines suggest the use of chlorine bleach or other disinfectants like alcohols, after scrubbing and clean-up, to sanitise surfaces because of the likely sewage (bacterial) contamination. This approach is consistent with Mycologia’s practices and advice in these specific circumstances. However when needed, Mycologia generally use alcohols or more human friendly oxidizers like hydrogen peroxide for a sanitising during final remediation steps.

References on the Biocidal Effects of mould cleaning solutions

Effectiveness of six different disinfectants on removing five microbial species and effects on the topographic characteristics of acrylic resin,. K da Silva et al, J Prosthodont Epub, 17(8):627-33. 2008,


Effectiveness of common household cleaning agents in reducing the viability of human influenza. A/H1N1PLoS One. JS Greatorex, US NIH, Feb 1;5(2):e8987, 2010.


Moulds in containers with biological wastes, J Reiss, Microbiol Res. Mar; 150(1):93-8,1995.


Reduction of Poliovirus 1, bacteriophages, Salmonella montevideo, and Escherichia coli O157:H7 on strawberries by physical and disinfectant washes, J Lukasik, et al, J Food Prot. Feb;66(2):188-93, 2003. 


Antimicrobial activity of olive oil, vinegar, and various beverages against foodborne pathogens. E Medina E, et al, J Food ProtMay;70(5):1194-9, 2007.


Analysis and Evaluation of Preventive Control Measures for the Control and Reduction/Elimination of Microbial Hazards on Fresh and Fresh-Cut Produce, Chapter V. Methods to Reduce/Eliminate Pathogens from Produce and Fresh-Cut Produce, US Food and Drug Administration (US FDA),


AOEC references for designating bleach as an asthmagen

  • Rosenman KD, et al. Cleaning products and work-related asthma. J Occup EnvironMed 2003 May;45(5):556-63.
  • Mazurek JM, et al. Work-Related Asthma in the Educational Services Industry: California,Massachusetts,Michigan, and New Jersey, 1993–2000.AMERICAN JOURNAL OF INDUSTRIALMEDICINE 51:47–59 (2008).
  • Association of Occupational and Environmental Clinics. Revised Protocol: Criteria for Designating Substances as Occupational Asthmagens on the AOEC List of Exposure Codes. Revised September 2008. Retrieved at
  • AOEC Exposure Code List, Display All Asthmagens.Accessible at
  • D’Alessandro A, KuschnerW,Wong H, Boushey HA, Blanc PD. Exaggerated responses to chlorine inhalation among persons with nonspecific airway hyperreactivity. Chest 1996; 109:331-337.
  • Sastre J,MaderoMF, Fernandez-NietoM, Sastre B, del Pozo V,  Garcia-del PotroM, Quirce S. Airway response to chlorine inhalation(bleach)      among cleaning workers with and without bronchial hyperresponsiveness. .AmJIndMed 2011; 54:293-299.
  • Arif AA, Delclos GL. Association between cleaning-related chemicals and work-related asthma and asthma symptoms among healthcare professionals. Occup EnvironMed 2012; 69:35-40

Mycologia’s core business is in providing investigation and solution-based services in Environmental Mycology, IAQ, Building & HVAC Investigations and Remediation of Mould and Asbestos.