Peracetic Acid in Environmental Cleaning: Moving Beyond Chlorine
Introduction
Environmental cleaning is central to infection prevention in healthcare. High touch surfaces, shared equipment, and wet areas such as sinks and drains all contribute to the microbial burden that can support transmission of healthcare associated pathogens. Chlorine based disinfectants have been widely used for decades, particularly where sporicidal activity is required, but they present limitations such as reduced efficacy in the presence of organic soil, material compatibility issues, and the formation of chlorinated disinfection by products.
Peracetic acid, often referred to as PAA, is a powerful oxidising disinfectant that maintains activity under conditions that commonly challenge chlorine based agents. It has broad spectrum microbicidal action, an attractive environmental breakdown profile, and strong performance in the presence of organic load. These characteristics have led to increased interest in PAA for both routine and targeted environmental disinfection. This article reviews the science behind PAA, compares it with chlorine based products, and considers how it may be incorporated into environmental cleaning programmes in New Zealand and Australia.
Oxidising disinfectants in healthcare environmental cleaning
Guidelines for disinfection and sterilisation in healthcare emphasise the need for disinfectants with proven efficacy against bacteria, viruses, fungi, and spores (Centers for Disease Control and Prevention [CDC], 2023a). Oxidising chemistries, including chlorine releasing agents, hydrogen peroxide, and peroxyacids such as peracetic acid, are widely used because they are broad spectrum and have rapid contact times (Assadian et al., 2021). High level disinfectants such as chlorine dioxide, PAA, and hydrogen peroxide are recognised for their ability to inactivate spores when correctly formulated and applied (CDC, 2023b).
However, real world surfaces often contain organic material such as body fluids and environmental soils. Disinfectants must therefore perform reliably in these conditions if they are to be effective in practice.
Limitations of chlorine based disinfectants
Chlorine based disinfectants, particularly sodium hypochlorite, remain common because they are inexpensive and familiar. Their microbicidal activity relies on free available chlorine, especially hypochlorous acid, which is highly reactive (CDC, 2023b).
This reactivity is a limitation when organic material is present. Organic soil rapidly consumes free chlorine, reducing the concentration available for disinfection. Experimental studies consistently show reduced efficacy of sodium hypochlorite in the presence of organic load (Morris et al., 2023). Similar effects are observed across a variety of healthcare relevant surfaces and soils.
Additional drawbacks of chlorine based disinfectants include:
• formation of chlorinated disinfection by products, including trihalomethanes and haloacetic acids, which raise occupational and environmental concerns (Li et al., 2025)
• potential for corrosion or surface damage with frequent use (CDC, 2023b)
• strong odours that may affect staff acceptance and indoor air quality
These limitations have prompted interest in alternative oxidising chemistries that offer consistent performance in more challenging environmental conditions.
Peracetic acid: chemistry and mechanism of action
Peracetic acid is an organic peroxyacid formed from acetic acid and hydrogen peroxide in equilibrium. It acts as a potent oxidising agent capable of damaging cell membranes, proteins, and nucleic acids (CDC, 2023a).
PAA has broad antimicrobial efficacy, including activity against:
• Gram positive and Gram negative bacteria
• fungi and yeasts
• mycobacteria
• a wide range of viruses
• spores when used at appropriate concentrations and contact times (CDC, 2023a)
PAA is active at low concentrations. Vegetative bacteria and fungi can be inactivated within minutes at concentrations below 100 ppm. In the presence of organic matter, concentrations in the range of 200 to 500 ppm are typically required, while spores may require 500 to 10 000 ppm depending on contact time (CDC, 2023a).
For environmental cleaning, a key attribute is that PAA retains activity in the presence of organic soil to a greater extent than chlorine based agents, making it more reliable on surfaces that cannot be thoroughly pre cleaned.
Efficacy in dirty conditions and on biofilms
Studies simulating healthcare conditions have shown that oxidising disinfectants containing peracetic acid maintain sporicidal efficacy in both clean and soiled conditions. Brown et al. (2024) demonstrated that PAA disinfectants remain stable and effective even when organic load is present, with only modest reductions in active concentration over time.
Dry surface biofilms, which commonly form on hospital surfaces, are far more tolerant of disinfectants than planktonic cells. Chowdhury et al. (2019) found that PAA based formulations produced significant reductions in Staphylococcus aureus dry surface biofilms, including in the presence of organic soil.
Broader reviews of biofilm control also identify PAA as a consistently effective oxidising agent. Laboratory work demonstrated that PAA at approximately 900 ppm achieved greater than a 6 log₁₀ reduction in Pseudomonas aeruginosa biofilms under standardised test conditions (Marchetti et al., 2018). This reflects PAA’s ability to penetrate extracellular polymeric substance layers and disrupt biofilm structure more effectively than many chlorine based products.
These findings support the suitability of PAA for use in high soil and biofilm prone environments such as drains, overflow channels, textured flooring, and other difficult to clean niches.
Environmental and by product profile
A significant advantage of PAA is its breakdown into acetic acid, oxygen, and water. It does not form chlorinated organic by products, which are a concern with repeated chlorine use (Li et al., 2025).
Comparative studies have highlighted PAA as a more environmentally favourable oxidant in many applications, although it remains a strong chemical that must be handled with appropriate controls (Wang et al., 2023).
In healthcare settings where disinfectants are used frequently and often enter wastewater streams, this profile is appealing, particularly for facilities aiming to reduce chlorinated wastewater outputs or achieve sustainability goals.
Practical advantages and limitations
Peracetic acid based disinfectants offer several advantages:
• broad spectrum efficacy including spores
• reliable performance in the presence of organic load (Brown et al., 2024)
• meaningful reductions in biofilms in laboratory models (Marchetti et al., 2018)
• absence of chlorinated by products
However, PAA must be used thoughtfully:
• concentrated PAA is corrosive and requires appropriate dilution, ventilation, and personal protective equipment (CDC, 2023b)
• compatibility with local surfaces should be assessed, as PAA can affect certain metals and plastics (CDC, 2023b)
• PAA solutions have a vinegar like odour from acetic acid, though typically less intrusive than high chlorine odours
These considerations mean that PAA should be incorporated based on local needs, risk assessments, and material compatibility reviews.
Applications in environmental cleaning and drains
Peracetic acid is already used as a high level disinfectant for certain medical devices (CDC, 2023a). Its extension into environmental cleaning is supported by evidence of strong performance against organic soil and biofilms.
Potential applications in environmental cleaning include:
• routine disinfection of high risk surfaces
• targeted decontamination during outbreaks
• scheduled disinfection of drains and wet areas
Of particular interest is the use of PAA in drains. Biofilms in sink traps and drain lines are well documented reservoirs of Gram negative organisms. Foaming PAA formulations that reach the upper drain and trap area allow extended contact times and can dislodge organic material. Studies have shown that scheduled use of PAA based drain disinfectants can reduce total aerobic counts and organisms of concern over periods of weeks (Sharrocks et al., 2024).
Given that New Zealand and Australian hospitals share similar plumbing configurations and pathogen profiles with the sites studied internationally, these findings are highly relevant to local practice.
Implications for New Zealand and Australian healthcare
Hospitals in New Zealand and Australia face increasing expectations for strong environmental hygiene, rapid outbreak response capability, and sustainable cleaning practices. Within national guidelines, facilities have flexibility in selecting disinfectants provided they are approved and used correctly (Australian Commission on Safety and Quality in Health Care, 2024).
Peracetic acid based formulations provide an opportunity to:
• strengthen environmental cleaning where organic soil is unavoidable
• reduce reliance on high strength chlorine solutions
• integrate drain disinfection into regular cleaning programmes
• support sustainability initiatives by limiting chlorinated by product formation
For organisations already considering routine drain disinfection, PAA provides a chemistry that performs well in wet, complex environments where chlorine based agents are often challenged.
Conclusion
Chlorine based disinfectants will continue to play an important role in healthcare. However, their reduced efficacy in the presence of organic soil, potential for material damage, and formation of chlorinated by products highlight the need for complementary chemistries. Peracetic acid offers strong oxidising action, broad microbicidal activity, and reliable performance in conditions that more closely mirror real healthcare environments.
Evidence demonstrates that PAA based disinfectants maintain efficacy under soiled conditions, achieve significant reductions in biofilms, and provide a practical option for difficult niches such as drains. For healthcare facilities in New Zealand and Australia, integrating PAA into environmental cleaning programmes can strengthen infection prevention, enhance sustainability, and provide a more resilient approach to managing environmental microbial risks.
References
Assadian, O., et al. (2021). Practical recommendations for routine cleaning and disinfection in healthcare facilities. Journal of Hospital Infection, 113, 172 to 180.
Australian Commission on Safety and Quality in Health Care. (2024). Australian guidelines for the prevention and control of infection in healthcare (current version).
Brown, L., et al. (2024). Assessing the stability and sporicidal efficacy of oxidizing disinfectants in clean and medical dirty conditions. Journal of Hospital Infection.
Centers for Disease Control and Prevention. (2023a). Peracetic acid sterilization. In Guideline for disinfection and sterilization in healthcare facilities.
Centers for Disease Control and Prevention. (2023b). Chemical disinfectants. In Guideline for disinfection and sterilization in healthcare facilities.
Chowdhury, D., et al. (2019). Effect of disinfectant formulation and organic soil on disinfectant efficacy against Staphylococcus aureus dry surface biofilm. Journal of Hospital Infection, 103, e33 to e41.
Li, J., et al. (2025). Mechanisms and potential for disinfection by product formation during peracetic acid disinfection. npj Clean Water.
Marchetti, R., Arghittu, A., & Lupi, E. (2018). Effectiveness of peracetic acid against bacterial biofilms in laboratory models and industrial environments. International Journal of Hygiene and Environmental Health, 221, 283 to 291.
Morris, J. N., et al. (2023). Efficacy of peracetic acid and sodium hypochlorite against microorganisms in the presence of organic matter. Applied and Environmental Microbiology, 89.
Sharrocks, K., et al. (2024). Use of a peracetic acid disinfectant to reduce total aerobic counts in hospital handwash basin drains. Journal of Hospital Infection.
Wang, D., et al. (2023). Peroxyacetic acid as a green alternative to sodium hypochlorite in disinfection applications. International Journal of Food Microbiology, 398, 110201.
