Disinfecting Canadian Daycares with Hypochlorous Acid Fogging

Highlights of This CleanSmart White Paper

This White Paper reviews the available scientific evidence, Canadian regulatory context, and practical considerations surrounding the use of hypochlorous acid fogging in Canadian daycare facilities. The key findings are summarized below.

• Canadian public health guidance recommends combining routine cleaning with appropriate disinfection of high-touch surfaces in daycare facilities to help reduce the spread of infectious diseases.
• The scientific evidence reviewed in this paper indicates that hypochlorous acid (HOCl) can be effectively applied by fogging to disinfect exposed hard surfaces when used under appropriate conditions.
• The strongest results are achieved when fogging is used as part of a comprehensive cleaning and disinfection program. It is intended to supplement routine cleaning—not replace it.
• Successful fogging depends on more than the equipment being used. The quality, formulation, stability, concentration, and proper use of the hypochlorous acid disinfectant also play an important role in achieving effective results.
• Although relatively few studies have been conducted in daycare facilities, laboratory and healthcare research provides a strong scientific basis for considering HOCl fogging as an effective method of disinfecting daycare hard surfaces.
• Health Canada regulates disinfectant products by approving their claims, directions for use, and authorized application methods. A daycare's decision to use fogging is an operational decision that falls within a broader framework of product label compliance, public health guidance, workplace safety, and safe facility implementation.
  

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1. Executive Summary

1.1 Objective

To determine whether hypochlorous acid (HOCl) can be effectively applied by fogging to disinfect surfaces in daycare facilities, and to evaluate how fogging is treated within current Canadian regulatory and public health guidance.

1.2 Background

CleanSmart has received recurring questions from daycare operators and other organizations about applying hypochlorous acid using fogging equipment. The main questions are straightforward: Does hypochlorous acid fogging effectively reduce microorganisms on frequently touched surfaces throughout a daycare facility? Does the scientific evidence support this method of application? Does Health Canada regulate the use of fogging?

To answer these questions, CleanSmart reviewed Canadian public health guidance, Health Canada regulatory principles, international guidance, and peer-reviewed scientific research on HOCl fogging and similar application methods. The key findings are summarized below, with the supporting evidence presented in the sections that follow.

1.3 Key Findings

The research identified the following key findings.

• Canadian public health authorities consistently recommend routine cleaning followed by appropriate disinfection of high-touch surfaces in daycare facilities. The scientific evidence reviewed for this white paper supports this approach, indicating that fogging is most effective when used to supplement routine manual cleaning rather than replace it. (See Sections 2.1, 2.4, and 2.7.)
• The peer-reviewed scientific literature provides moderate to strong evidence that HOCl fogging is an effective method of applying hypochlorous acid to exposed hard surfaces under appropriate conditions. In practical terms, this means the available research consistently demonstrates that the application method works in laboratory and healthcare environments. Although relatively little research has been conducted specifically in daycare facilities, the evidence provides a reasonable scientific basis for daycare operators to consider fogging as one method of applying hypochlorous acid within a comprehensive cleaning and disinfection program. (See Section 2.4.)
• The effectiveness reported in peer-reviewed studies depends not only on the fogging method, but also on using a properly formulated and manufactured hypochlorous acid disinfectant that consistently maintains the characteristics needed to perform effectively throughout its intended shelf life. (See Section 2.5.)
• Peer-reviewed laboratory and healthcare studies consistently demonstrate that HOCl fogging can significantly reduce bacterial and viral contamination on treated hard surfaces when supported by a properly formulated and manufactured hypochlorous acid disinfectant, appropriate application practices, and a comprehensive cleaning and disinfection program. (See Section 2.4.)
• Health Canada authorizes disinfectant products through the Drug Identification Number (DIN) process and approves the claims, directions for use, and authorized application methods that manufacturers may include on the approved product label. This regulatory role applies to the hypochlorous acid disinfectant product—not to a daycare's operational decision to use fogging. (See Section 2.6.)
• A daycare's decision to implement fogging as an operational disinfection method is governed through a broader framework that includes compliance with the approved product label, applicable public health guidance, occupational health and safety requirements, and safe facility-level implementation. (See Section 2.6.)

1.4 Practical Implications

The scientific and regulatory evidence reviewed for this paper indicates that daycare operators may reasonably consider hypochlorous acid fogging as one method of applying disinfectant within a comprehensive cleaning and disinfection program. Successful implementation depends on selecting an appropriate hypochlorous acid disinfectant, applying it correctly, and integrating fogging with routine manual cleaning rather than using it as a replacement.

Health Canada's role is to authorize disinfectant products and approve the claims, directions for use, and application methods that manufacturers may include on product labels. A daycare's operational decision to implement fogging, however, is beyond Health Canada's jurisdiction. Operators should always read and follow the approved directions for use on the manufacturer's hypochlorous acid disinfectant product label, applicable public health guidance, occupational health and safety requirements, ventilation, occupancy, staff training, and facility-specific implementation practices.

The supporting report explains these scientific, regulatory, and practical considerations in greater detail so that daycare operators can make informed decisions based on the available evidence.

Additional educational resources related to daycare hygiene are available within the CleanSmart Daycare Hygiene Series.

2. Supporting Analysis

2.1 Why Effective Environmental Disinfection Matters in Daycare Facilities

2.1.1 Why Environmental Disinfection Matters

Licensed daycare facilities play an essential role in supporting children's learning, development, and social interaction. They also present unique infection prevention challenges. Young children frequently share toys, learning materials, furniture, and washroom facilities, while close physical contact between children and caregivers creates many opportunities for microorganisms to spread throughout the environment. Because many children are still developing good hand hygiene habits and often place objects in their mouths, frequently touched surfaces such as toys, tables, diaper-changing stations, sinks, door handles, light switches, and other shared hard surfaces can become important pathways for the transmission of infectious diseases.

Throughout this paper, these hard surfaces are collectively referred to as environmental surfaces. This term includes tables, toys, countertops, diaper-changing stations, sinks, door handles, light switches, and other frequently touched hard surfaces within the daycare environment.

Although this paper focuses on licensed Canadian daycare facilities, many of the environmental hygiene principles discussed also apply to schools, healthcare clinics, offices, veterinary practices, and other commercial buildings where high-touch environmental surfaces require routine disinfection. Daycare facilities, however, require particular attention because they combine frequent hand-to-surface contact, shared equipment, and young children who are generally more susceptible to common infectious illnesses. 

2.1.2 Public Health Guidance for Environmental Hygiene

Canadian public health authorities consistently recommend a structured approach to environmental hygiene that combines routine cleaning with appropriate disinfection of surfaces that are touched frequently or are likely to become contaminated. Guidance from provincial and local public health agencies identifies items such as tables, toys, diaper-changing stations, sinks, toilets, door handles, light switches, cots, and shared learning equipment as priorities for routine environmental hygiene because they are handled repeatedly throughout the day and may contribute to indirect disease transmission.

2.1.3 Cleaning and Disinfection Are Different Processes

It is also important to distinguish between cleaning and disinfection, as the two terms are often used interchangeably even though they serve different purposes. Cleaning removes visible dirt, organic material, and many microorganisms from a surface. Disinfection is the subsequent process of using an approved disinfectant to inactivate or destroy remaining disease-causing microorganisms on a clean surface. Public health guidance consistently emphasizes that effective disinfection begins with proper cleaning because accumulated soil and organic matter can reduce the performance of many disinfectants.

For daycare operators, the objective is not to sterilize every surface continuously. Instead, it is to implement a practical, repeatable environmental hygiene program that reduces the risk of disease transmission while supporting a safe and healthy environment for children and staff. Once the need for effective environmental disinfection has been established, the next question becomes which disinfectants are well suited to this purpose. The following section examines why hypochlorous acid has attracted increasing interest for routine environmental disinfection.

2.2 Why Hypochlorous Acid Is Well Suited to Daycare Facilities

2.2.1 Broad-Spectrum Antimicrobial Activity

Once the need for effective environmental disinfection has been established, the next question is which disinfectant is appropriate for routine use in a daycare environment. Daycare operators require products that are effective against a broad range of disease-causing microorganisms while also being practical for frequent use on the many hard, non-porous surfaces found throughout childcare facilities. In recent years, hypochlorous acid (HOCl) has received increasing attention because it combines broad-spectrum antimicrobial activity with characteristics that make it well suited to routine environmental disinfection. Readers seeking a broader introduction to hypochlorous acid before reviewing the research presented in this paper may also find the CleanSmart What Is Hypochlorous Acid? Authority Page helpful.

Peer-reviewed scientific studies have shown that hypochlorous acid is effective against a wide variety of microorganisms, including bacteria, viruses, fungi, and biofilms when applied using appropriately formulated disinfectant products and established cleaning and disinfection practices. This broad-spectrum activity has led to its use in healthcare, food processing, agriculture, and other settings where maintaining hygienic hard surfaces is important. Although relatively few published studies have focused specifically on daycare facilities, the extensive microbiological evidence supporting hypochlorous acid surface disinfection provides a strong scientific basis for evaluating its potential use in childcare environments.

2.2.2 Practical Advantages for Routine Daycare Disinfection

In addition to its antimicrobial performance, hypochlorous acid has characteristics that are attractive for facilities occupied by young children. The scientific literature frequently describes appropriately formulated HOCl solutions as having a favourable safety profile, producing little or no residue after use, and being compatible with many common hard surfaces. These characteristics make HOCl particularly suitable for routine environmental disinfection where repeated application throughout the day may be necessary. As with any disinfectant, products should always be used according to the manufacturer's directions and any applicable regulatory requirements.

2.2.3 Transition to Application Methods

Another practical advantage is that hypochlorous acid can be applied using several different delivery methods. Depending on the product and its approved directions for use, hypochlorous acid may be applied manually using spray bottles or similar applicators, or by automated application methods such as fogging, electrostatic spraying, or ultra-low volume (ULV) misting. This flexibility has contributed to growing interest in evaluating whether fogging can provide an efficient method of delivering HOCl to environmental surfaces in facilities such as daycares, schools, and healthcare environments.

It is important, however, not to assume that every application method performs equally well simply because the same disinfectant is being used. The effectiveness of any application method must be supported by scientific evidence. The following section explains what fogging is, how it works, and why organizations use it as one approach to environmental surface disinfection.

2.3 Understanding Hypochlorous Acid Fogging

2.3.1 What Is Fogging?

Before evaluating whether fogging is an effective method of applying hypochlorous acid, it is helpful to understand what fogging is and why organizations use it. Fogging is simply one method of applying a liquid disinfectant by converting it into a fine mist of small droplets that settle onto exposed environmental surfaces. Unlike manual spray application, which typically treats one surface at a time, fogging is designed to distribute a disinfectant more broadly throughout an unoccupied room.

During a fogging application, specialized equipment produces a controlled mist that remains suspended in the air long enough for droplets to disperse throughout the treatment area before settling onto surfaces. Depending on the equipment being used, the mist can reach many exposed objects within the room, including tables, chairs, shelving, toys, countertops, and other frequently touched surfaces. Fogging is intended to supplement—not replace—routine manual cleaning by providing an efficient method of applying an approved disinfectant across multiple surfaces.

2.3.2 Where Fogging Is Used

Organizations may consider fogging when they need to disinfect areas containing numerous hard surfaces that would otherwise require extensive manual application of a disinfectant. Healthcare facilities, schools, commercial buildings, veterinary clinics, and other institutional environments have all evaluated fogging as a means of improving application efficiency, particularly during terminal cleaning or after periods of increased disease transmission. Although this paper focuses on daycare facilities, the scientific studies discussed in the following section were conducted in a variety of settings, many of which provide useful evidence regarding the performance of hypochlorous acid when delivered by fogging.

2.3.3 Related Application Technologies

The term fogging is sometimes used alongside other application technologies, including ultra-low volume (ULV) misting, whole-room atomizing, and electrostatic spraying. These technologies differ in how they generate and distribute disinfectant droplets, but they share a common objective: to apply an approved disinfectant efficiently to environmental surfaces. A detailed comparison of these application methods is beyond the scope of this paper because the objective here is to evaluate fogging as the delivery method most relevant to the question posed by daycare operators.

2.3.4 Transition to the Scientific Evidence

Understanding what fogging is does not answer whether it is effective. The critical question is whether peer-reviewed scientific research demonstrates that fogging can successfully deliver hypochlorous acid to environmental surfaces and achieve meaningful reductions in disease-causing microorganisms. The following section examines the available scientific evidence.

2.4 What Does the Scientific Evidence Show?

The central question addressed by this white paper is whether fogging is an effective method of applying hypochlorous acid (HOCl) for environmental surface disinfection. To answer this question, CleanSmart reviewed peer-reviewed scientific literature evaluating hypochlorous acid delivered by fogging, whole-room atomizing, dry fogging, ultra-low volume (ULV) misting, and related automated application technologies. Although relatively few studies were conducted specifically in daycare facilities, the available research from laboratory and healthcare environments provides valuable evidence regarding the effectiveness of HOCl fogging under controlled conditions.

Taken together, the available evidence demonstrates that fogging can be an effective method of delivering hypochlorous acid to environmental surfaces. The strongest findings consistently show that HOCl fogging can significantly reduce bacterial and viral contamination when used appropriately, particularly as part of a comprehensive cleaning and disinfection program rather than as a replacement for routine cleaning. While individual studies differ in their methods and objectives, the overall direction of the evidence is remarkably consistent.

2.4.1 Laboratory Studies

Laboratory studies are often the first step in determining whether a disinfectant works as intended. By carefully controlling conditions such as the amount of bacteria present, the disinfectant concentration, and the contact time, researchers can determine whether hypochlorous acid remains effective when delivered by fogging.

2.4.1.1 Evidence from Controlled Laboratory Studies

Studies examining hypochlorous acid delivered by fogging or dry fog systems have demonstrated substantial reductions in a variety of microorganisms, including bacteria and viruses, under these controlled conditions. In several studies, researchers reported reductions exceeding three logarithmic units (99.9%) and, in many cases, greater than five logarithmic units (99.999%), levels generally regarded as indicative of highly effective environmental surface disinfection. In practical terms, these studies showed that hypochlorous acid fogging was able to remove nearly all detectable microorganisms from treated surfaces under controlled laboratory conditions.

These laboratory investigations establish an important scientific principle: hypochlorous acid can retain its antimicrobial effectiveness when delivered as a fine mist, provided the disinfectant is appropriately formulated and applied under suitable conditions.

2.4.2 Healthcare Studies

Healthcare environments provide a practical setting for evaluating whole-room disinfection technologies because patient rooms contain numerous high-touch surfaces and require rigorous infection prevention practices. Although healthcare facilities differ from daycare centres, they present many of the same environmental hygiene challenges, including numerous high-touch surfaces and the need to reduce the spread of infectious diseases. As a result, healthcare studies provide valuable evidence about how well fogging performs under demanding real-world conditions.

2.4.2.1 Evidence from Healthcare Facilities

Healthcare facilities are among the most demanding environments for infection prevention, which makes them useful places to evaluate new disinfection methods before they are considered for other settings. Several peer-reviewed studies examined whether adding hypochlorous acid fogging after normal manual cleaning could further reduce bacteria on environmental surfaces.

The results were encouraging. Researchers consistently found that rooms treated with both manual cleaning and HOCl fogging had substantially less bacterial contamination than rooms cleaned by manual methods alone. In one widely cited study, adding whole-room HOCl atomization approximately doubled the overall reduction in bacteria compared with manual cleaning by itself. Researchers also found that bacteria were much less likely to be transferred from one surface to another after the fogging treatment had been completed. 

These findings are important because they suggest that fogging can improve the distribution of disinfectant across exposed surfaces throughout a room. Equally important, the researchers did not evaluate fogging as a replacement for manual cleaning. Instead, they studied it as an additional step performed after normal cleaning had already been completed.

2.4.3 Virus Studies

Several peer-reviewed investigations have evaluated HOCl fogging against viruses of public health importance, including influenza viruses, human norovirus surrogates, and SARS-CoV-2.

2.4.3.1 Evidence Against Viral Contamination

Overall, these studies demonstrate that hypochlorous acid delivered by fogging can effectively inactivate viruses on environmental surfaces, although effectiveness varies according to the virus, disinfectant concentration, contact time, and study conditions.

The evidence also illustrates that not all viruses respond equally. Influenza viruses were generally inactivated at lower HOCl concentrations than SARS-CoV-2 in dry fog experiments, while studies involving human norovirus surrogates reported substantial reductions using optimized fogging protocols. These differences reinforce an important principle that will be explored later in this paper: successful disinfection depends not only on the delivery method but also on using an appropriately formulated disinfectant under suitable operating conditions. 

For daycare operators, these findings indicate that hypochlorous acid fogging has the potential to reduce contamination from viruses that commonly spread through shared environments. However, the studies also show that effectiveness depends on using the disinfectant under appropriate conditions rather than assuming all viruses respond in the same way.

2.4.4 Bacterial Studies

The strongest and most consistent body of evidence relates to bacterial surface contamination.

2.4.4.1 Evidence Against Bacterial Contamination

Multiple laboratory and healthcare studies demonstrated that HOCl fogging substantially reduced environmental bacterial populations on hard surfaces, including organisms associated with healthcare-associated infections and multidrug-resistant bacteria. In several investigations, bacterial contamination was reduced to very low or undetectable levels following whole-room treatment, although treatment times and operating conditions varied between studies. Collectively, these studies provide strong evidence that fogging can effectively deliver hypochlorous acid to exposed environmental surfaces where bacterial contamination is present.

For daycare operators, these findings provide reassurance that fogging can effectively disinfect the hard surfaces children and staff touch throughout the day when it is used correctly as part of a comprehensive cleaning program.

2.4.5 Operational Studies

In addition to microbiological performance, researchers have evaluated the practical implications of whole-room HOCl application.

2.4.5.1 Operational Findings

Several studies reported more consistent coverage of exposed environmental surfaces, reduced opportunities for cross-contamination during terminal cleaning, and improvements in labour efficiency compared with relying solely on manual application methods. These operational benefits help explain why healthcare facilities and other institutions continue to evaluate fogging technologies as part of broader environmental hygiene programs.

At the same time, the literature consistently identifies important limitations. Most studies were conducted in controlled laboratory environments or unoccupied healthcare rooms rather than active daycare facilities. Researchers also emphasized that fogging should supplement—not replace—routine cleaning and that applications should follow appropriate safety procedures, product directions, and occupancy requirements. These limitations should be considered when applying published findings to daycare environments. In practice, these studies suggest that daycare operators should view fogging as one component of a broader environmental hygiene program rather than as a stand-alone solution.

2.4.6 Scientific Conclusions

2.4.6.1 Overall Conclusions

The peer-reviewed scientific literature provides moderate to strong evidence that fogging is an effective method of applying hypochlorous acid to exposed hard surfaces when supported by a properly formulated disinfectant, appropriate application practices, and a comprehensive cleaning and disinfection program. Although relatively few studies have been conducted specifically in daycare facilities, the consistency of findings across laboratory and healthcare environments provides a reasonable scientific basis for daycare operators to consider HOCl fogging as an effective method of applying hypochlorous acid within a comprehensive cleaning and disinfection program.

The research also points to an important observation that extends beyond the fogging equipment itself. The studies demonstrating successful outcomes carefully characterized the hypochlorous acid solutions they evaluated, including factors such as concentration, formulation, and operating conditions. These observations suggest that achieving similar results in practice depends on more than selecting an appropriate fogging device. The characteristics of the hypochlorous acid disinfectant also play an important role. The following section examines these factors in greater detail.

2.5 Factors That Influence Successful HOCl Fogging

The scientific studies reviewed in the previous section demonstrate that hypochlorous acid fogging can effectively reduce microorganisms on environmental surfaces. An important question remains, however: if the published studies achieved these results, what conditions made them successful?

A common misconception is that successful fogging depends primarily on selecting the right fogging equipment. The scientific literature suggests otherwise. Researchers carefully documented the characteristics of the hypochlorous acid solutions they evaluated because the performance of the disinfectant itself was an important part of the study. In other words, achieving effective disinfection depends on both how the disinfectant is applied and the quality and characteristics of the disinfectant being applied.

2.5.1 Not All Hypochlorous Acid Solutions Are Identical

Although products may all be described as hypochlorous acid, they are not necessarily identical. The studies reviewed for this paper consistently described important characteristics of the disinfectant being evaluated, including its concentration, pH, available free chlorine (FAC), stability, and contact time. These factors were reported because they influence how the disinfectant performs under the conditions being studied.

For daycare operators, the practical message is straightforward: the successful outcomes reported in scientific studies were achieved using carefully characterized disinfectant solutions rather than simply any product labelled as hypochlorous acid.

2.5.2 Concentration and Contact Time

One of the most frequently reported characteristics in the scientific literature is disinfectant concentration. Researchers selected concentrations appropriate for the microorganisms being evaluated and then allowed sufficient contact time for the disinfectant to work.

In practical terms, both factors matter. Even an effective disinfectant may not achieve the expected results if it is used at a concentration or contact time that differs from the product's approved directions for use. Following the manufacturer's label instructions is therefore an essential part of achieving effective environmental disinfection.

2.5.3 Stability and Product Quality

Another recurring theme in the literature is product stability. Hypochlorous acid is an effective disinfectant because of its chemical properties, but those properties must remain stable from the time the product is manufactured until it is used.

Researchers therefore reported information about the disinfectant they evaluated so that other scientists could reproduce their work and compare results between studies. This level of characterization helps explain why published research carefully identifies the properties of the hypochlorous acid solution rather than referring simply to "HOCl."

For daycare operators, this reinforces an important point: the successful outcomes reported in the scientific literature were achieved using carefully characterized hypochlorous acid disinfectants. Achieving similar results in practice begins with selecting a properly formulated and consistently manufactured product, then storing and using it according to the manufacturer's approved directions for use.

2.5.4 Manufacturing Consistency

Scientific research depends on consistency. If the properties of a disinfectant change significantly from one batch to another, researchers cannot confidently compare results or reproduce their findings.

For this reason, published studies typically describe the disinfectant used in sufficient detail to allow others to understand the conditions under which the research was conducted. While daycare operators do not need to understand the underlying chemistry, they should recognize that the products evaluated in peer-reviewed studies were carefully characterized before testing began.

2.5.5 Overall Interpretation

The scientific evidence reviewed for this white paper demonstrates that successful HOCl fogging depends on more than selecting an appropriate fogging device. It also depends on selecting a properly formulated and consistently manufactured hypochlorous acid disinfectant, following the approved directions for use on the product label, and implementing the application within a comprehensive cleaning and disinfection program.

For daycare operators, the practical implication is clear. Choosing a suitable fogging system is only one part of an effective environmental disinfection program. Equal attention should be given to selecting a properly formulated and consistently manufactured hypochlorous acid disinfectant, storing it according to the manufacturer's recommendations, following the approved directions for use on the product label, and implementing fogging within the broader public health and workplace safety framework discussed in the following sections.

The factors introduced in this section are discussed only briefly because they extend beyond the primary objective of this white paper. Readers interested in a more detailed examination of how concentration, pH, available free chlorine, stability, manufacturing quality, and other factors influence hypochlorous acid performance should refer to the companion authority white paper dedicated to those topics.

2.6 What Do Health Canada and Other Authorities Say?

The scientific evidence reviewed in this paper demonstrates that hypochlorous acid can be effectively delivered to environmental surfaces by fogging when used under appropriate conditions. Scientific effectiveness, however, is only one part of the decision facing a Canadian daycare operator. Before implementing any disinfectant application method, operators should also understand the regulatory and public health framework that governs disinfectant use in Canada.

Many people assume that one organization approves every aspect of disinfectant fogging. Instead, responsibility is shared among several authorities, each with a different role. Understanding these roles helps explain why scientific evidence, product authorization, workplace safety, and public health guidance must all be considered together.

2.6.1 Health Canada and the Drug Identification Number (DIN)

Health Canada regulates disinfectant products that are sold in Canada. For hard-surface disinfectants, authorization is demonstrated by a Drug Identification Number (DIN), which confirms that the product has been reviewed and approved for the claims, directions for use, and conditions described in its regulatory authorization.

A DIN applies only to the specific product that has been authorized. It does not represent approval of hypochlorous acid as a category, nor does it automatically apply to other products containing the same active ingredient. For daycare operators, confirming that a disinfectant carries a valid DIN is an important first step in selecting an appropriate product.

2.6.2 Why the Approved Product Label Matters

Health Canada authorizes both the disinfectant product and the conditions under which it may be marketed. The approved product label forms part of that authorization by specifying important information such as:

• intended uses;
• microorganisms covered by the approved claims;
• contact times;
• surfaces;
• directions for use;
• precautions and safety information.

If a particular application method, such as fogging, electrostatic spraying, or ULV misting, is included on the approved label, the manufacturer may promote the product for that purpose. If the application method does not appear on the approved label, the manufacturer generally cannot advertise or market the product for that use, even though the product itself remains an authorized disinfectant. This distinction is important because authorization of a disinfectant product and authorization of a particular marketing claim are related but separate regulatory considerations.

2.6.3 Public Health Authorities Focus on Outcomes Rather Than Technology

Provincial, regional, and municipal public health authorities play a different role from Health Canada. The guidance reviewed for this paper shows remarkable consistency across Canada. Public health authorities consistently emphasize:

• routine cleaning;
• appropriate environmental disinfection;
• attention to high-touch surfaces;
• following manufacturer instructions;
• effective infection-prevention practices.

The Canadian public health guidance reviewed for this white paper does not specifically mention fogging, electrostatic spraying, ultra-low volume (ULV) misting, or other automated disinfectant application technologies for licensed daycare facilities. Similarly, the guidance reviewed does not identify a public health approval process requiring daycare operators to obtain authorization before implementing fogging.

Instead, the public health guidance consistently focuses on the outcomes daycare operators are expected to achieve, including effective environmental cleaning, appropriate disinfection, infection prevention, and safe operational practices. The guidance generally does not prescribe how disinfectants should be applied, leaving operational implementation decisions to daycare operators within the broader regulatory and workplace safety framework discussed in this paper.

2.6.4 The Role of Occupational Health and Safety

When fogging is used, additional workplace considerations may apply. Occupational health and safety requirements may address issues such as worker exposure, room occupancy, ventilation, staff training, and safe operating procedures. These requirements are generally administered through provincial workplace safety legislation rather than Health Canada's disinfectant authorization process. Consequently, implementing fogging involves more than selecting an effective disinfectant. Operators should also ensure that the application method can be used safely within their workplace.

2.6.5 What This Means for Daycare Operators

Taken together, the available evidence indicates that no single Canadian authority provides blanket approval or prohibition of disinfectant fogging in daycare facilities. Instead, Canadian governance operates through complementary responsibilities:

• Health Canada authorizes disinfectant products and their approved claims.
• Public health authorities provide infection-prevention guidance and inspect sanitation practices.
• Occupational health and safety authorities oversee worker safety where applicable.
• Daycare operators are responsible for implementing cleaning and disinfection procedures that comply with applicable regulatory requirements.

For daycare operators, the practical message is straightforward. Scientific evidence supports hypochlorous acid fogging as an effective method of delivering disinfectant to environmental surfaces under appropriate conditions. At the same time, operators should use a Health Canada-authorized disinfectant, follow the approved directions for use on the disinfectant product label, implement appropriate workplace safety practices, and consult their local public health authority whenever questions arise regarding local expectations or outbreak management.

2.7 Best Practices for Implementing HOCl Fogging

Scientific studies consistently show that successful hypochlorous acid (HOCl) fogging depends on more than selecting an appropriate disinfectant or fogging device. The greatest benefits are achieved when fogging is incorporated into a structured environmental hygiene program that combines routine cleaning, appropriate disinfection practices, regulatory compliance, and safe workplace procedures. The following best practices summarize the practical lessons drawn from the scientific literature and current Canadian guidance.

2.7.1 Clean Surfaces Before Fogging

Fogging should complement, not replace, routine cleaning. Dirt, food residue, organic matter, and other visible contamination can reduce the effectiveness of any disinfectant by preventing it from contacting microorganisms directly. High-touch surfaces should therefore be cleaned before disinfectant fogging is performed, particularly when visible soil is present. For daycare operators, this means maintaining normal daily cleaning routines and using fogging as an additional method of distributing disinfectant to environmental surfaces rather than as a substitute for cleaning.

What this means for daycare operators

Cleaning removes debris that can interfere with disinfectant performance, allowing the fogged disinfectant to contact surfaces more effectively.

2.7.2 Allow the Required Contact Time

A disinfectant requires sufficient time to remain on a surface in order to work as intended. Contact time varies by product and should always follow the approved directions for use on the disinfectant product label. Applying a disinfectant and allowing it to dry prematurely or removing it before the required contact time may reduce its effectiveness.

What this means for daycare operators

Using the correct contact time is just as important as selecting an appropriate disinfectant.

2.7.3 Apply Fogging When Areas Are Unoccupied

Many organizations perform fogging after children, staff, and visitors have left the area for the day. Scheduling fogging during unoccupied periods allows surfaces to remain undisturbed while the disinfectant works and provides time for any recommended ventilation procedures before normal occupancy resumes. Where workplace safety procedures or product directions specify ventilation or re-entry requirements, these should be followed.

What this means for daycare operators

Planning fogging outside normal operating hours can simplify implementation while supporting both safety and effective disinfection.

2.7.4 Ensure Staff Are Properly Trained

Even though modern fogging equipment is generally straightforward to operate, staff should understand:

• how to prepare the area;
• how to operate the equipment correctly;
• how to apply the disinfectant consistently;
• the required contact time;
• workplace safety procedures; and
• the approved directions for use on the disinfectant product label. 

Consistent application helps ensure that the procedures used in practice reflect those supported by the scientific evidence.

What this means for daycare operators

Proper training promotes both consistent disinfectant coverage and safe operation.

2.7.5 Use an Authorized Disinfectant Within the Applicable Governance Framework

Successful implementation requires attention to both the disinfectant product and the workplace in which it is used. Daycare operators should select a Health Canada-authorized disinfectant that is appropriate for the intended purpose and understand the approved conditions associated with that product.

The application procedure should also be incorporated into the daycare’s broader infection-prevention program. This includes meeting applicable workplace safety requirements related to staff training, room occupancy, ventilation, exposure control, and safe equipment operation. Where questions arise regarding the suitability of fogging within a particular facility, local expectations, or outbreak-management practices, operators should consult their local public health authority.

What this means for daycare operators

Effective implementation depends on using an appropriate authorized disinfectant and managing the fogging procedure within the applicable public health, childcare, and workplace safety framework.

2.7.6 Section Summary

Research reviewed throughout this paper indicates that HOCl fogging is most effective when it forms part of a comprehensive environmental hygiene program. Cleaning surfaces before disinfection, allowing the required contact time, performing fogging in unoccupied areas where appropriate, ensuring staff are properly trained, and following approved product directions together provide the foundation for achieving consistent and effective environmental surface disinfection in Canadian daycare facilities.

2.8 Practical Considerations

The scientific evidence reviewed throughout this paper indicates that hypochlorous acid (HOCl) fogging can be an effective method of distributing disinfectant to environmental surfaces when used under appropriate conditions. However, like any environmental hygiene practice, fogging is not the best solution for every situation. Daycare operators should consider both its practical advantages and its limitations when determining whether it fits their facility's cleaning and disinfection program.

2.8.1 Practical Advantages of Fogging

One of the principal advantages of fogging is its ability to distribute disinfectant over a large number of environmental surfaces in a relatively short period. This can help improve coverage of areas that may be difficult to reach consistently using manual wiping or spraying alone. Fogging may also improve consistency by applying disinfectant more uniformly throughout a room. In facilities containing numerous high-touch surfaces, this can simplify routine environmental disinfection while reducing the time required for manual application.

What this means for daycare operators

Facilities with multiple classrooms, large numbers of shared surfaces, or extensive daily cleaning requirements may find fogging to be a useful addition to their existing environmental hygiene program.

2.8.2 Practical Limitations

Fogging should not be viewed as a replacement for routine cleaning or as a solution for every environmental hygiene challenge. Visible dirt, food residue, and other organic material should still be removed before disinfectants are applied. Likewise, surfaces that require physical scrubbing or detailed cleaning will continue to benefit from manual cleaning methods.

Operational planning is also important. Because fogging is generally performed in unoccupied spaces, operators should consider scheduling, room access, ventilation requirements, and staff training when determining whether the approach is practical for their facility.

What this means for daycare operators

Fogging works best as one component of a broader cleaning and disinfection program rather than as a stand-alone solution.

2.8.3 When Manual Application May Be Preferable

Manual application remains appropriate in many situations. Small spills, localized contamination, frequently touched individual objects, and situations requiring immediate cleaning are often addressed more efficiently using a spray bottle, cloth, or wipe. Manual application may also be preferable where only a limited number of surfaces require treatment or when rooms remain occupied throughout the day and scheduled fogging is not practical.

What this means for daycare operators

Selecting the most appropriate application method depends on the cleaning task rather than assuming one approach is suitable for every situation.

2.8.4 Choosing the Right Approach for Your Facility

The research reviewed for this paper suggests that the decision to implement fogging should be based on operational needs rather than convenience alone. Factors such as facility size, cleaning frequency, occupancy patterns, staffing resources, infection-prevention objectives, and workplace safety requirements should all be considered when evaluating whether fogging is appropriate.

For some daycare facilities, manual application may adequately meet daily cleaning requirements. Others may determine that incorporating fogging into their environmental hygiene program provides additional operational efficiency while maintaining effective environmental surface disinfection.

What this means for daycare operators

The available evidence indicates that HOCl fogging can provide meaningful operational advantages in appropriate situations, but the decision should be based on the specific needs of the facility and implemented as part of a comprehensive environmental hygiene program rather than viewed as a universal solution.

2.8.5 Section Summary

The evidence reviewed in this paper suggests that HOCl fogging can be an effective addition to environmental surface disinfection programs in Canadian daycare facilities. Its greatest value is achieved when it complements routine cleaning, is selected because it meets the operational needs of the facility, and is implemented within a structured infection-prevention program. Daycare operators should evaluate both the advantages and the practical limitations of fogging to determine whether it is an appropriate component of their overall environmental hygiene strategy.

2.9 Conclusion

This white paper examined whether hypochlorous acid (HOCl) can be effectively applied by fogging to disinfect environmental surfaces in Canadian daycare facilities. The evidence was evaluated from three complementary perspectives: scientific research, practical implementation, and the Canadian regulatory framework.

The peer-reviewed scientific literature consistently supports HOCl fogging as an effective method of delivering disinfectant to environmental surfaces when used under appropriate conditions. Laboratory studies, healthcare investigations, and operational research demonstrate that properly applied HOCl fogging can achieve substantial reductions in microorganisms on treated surfaces while improving disinfectant distribution throughout an area.

The evidence also shows that successful outcomes depend on more than the fogging equipment itself. The characteristics of the disinfectant, appropriate application practices, contact time, routine cleaning, and workplace implementation all contribute to achieving the results reported in the scientific literature.

From a Canadian governance perspective, Health Canada authorizes disinfectant products and their approved claims, while provincial childcare requirements, public health guidance, occupational health and safety obligations, and facility-level infection prevention practices together influence how environmental disinfection is implemented within daycare facilities. These complementary responsibilities help ensure that effective environmental hygiene is achieved while maintaining appropriate regulatory oversight and workplace safety.

Taken together, the available evidence supports the conclusion that hypochlorous acid fogging can be an effective method of environmental surface disinfection in Canadian daycare facilities when an appropriate Health Canada-authorized disinfectant is used within a comprehensive environmental hygiene program and implemented in accordance with applicable regulatory, public health, and workplace safety requirements.

For daycare operators, the practical message is clear. Fogging should be viewed as one possible method of delivering disinfectant to environmental surfaces rather than as a replacement for routine cleaning or sound infection-prevention practices. When selected because it meets the operational needs of a facility and implemented thoughtfully within the broader governance framework, HOCl fogging represents a scientifically supported option for enhancing environmental surface disinfection in Canadian daycare settings.

Appendix A – Glossary

C.1 Purpose

This glossary explains technical, scientific, and regulatory terms used throughout this white paper. The definitions are written for a general audience and are intended to support understanding of the report rather than provide formal scientific or legal definitions.

C.2 Glossary

Available Free Chlorine (FAC)

The portion of chlorine in a disinfectant solution that is available to kill microorganisms. It is one of several factors that influence disinfectant performance.

Biofilm

A layer of microorganisms that attaches to a surface and is protected by a thin, sticky coating. Biofilms are generally more difficult to remove than free-floating microorganisms.

Contact Time

The amount of time a disinfectant must remain on a surface to achieve the level of microbial reduction stated on the product label.

Daycare Operator

The organization or individual responsible for implementing cleaning, disinfection, and infection prevention practices within a licensed childcare facility.

Disinfectant

A product designed to destroy or inactivate disease-causing microorganisms on hard, non-porous surfaces when used according to the manufacturer's approved directions for use.

Drug Identification Number (DIN)

A unique eight-digit number assigned by Health Canada to an authorized disinfectant or drug product. A DIN confirms that the specific product has been reviewed and authorized for sale in Canada under its approved conditions of use.

Environmental Surfaces

Hard surfaces within a facility that may become contaminated during normal activities, such as tables, toys, countertops, sinks, diaper-changing stations, door handles, and light switches.

Fogging

A method of applying a liquid disinfectant by converting it into a fine mist that settles onto exposed environmental surfaces. Fogging is intended to supplement routine cleaning rather than replace it.

Hypochlorous Acid (HOCl)

A chlorine-based disinfectant used to reduce or eliminate bacteria, viruses, fungi, and other microorganisms on hard surfaces. Different products containing hypochlorous acid may vary in formulation, stability, and performance.

Log Reduction

A scientific measurement used to describe how effectively microorganisms are reduced. For example, a 3-log reduction represents a 99.9% reduction, while a 5-log reduction represents a 99.999% reduction.

Microorganisms

Very small living organisms or infectious agents, including bacteria, viruses, fungi, and similar organisms that may cause disease.

Occupational Health and Safety (OHS)

The laws, regulations, and workplace practices intended to protect workers by promoting safe working conditions and appropriate use of equipment and chemicals.

Peer-Reviewed Study

Scientific research that has been independently evaluated by experts in the same field before publication to help ensure the quality and reliability of the findings.

Public Health Authority

A federal, provincial, regional, or municipal organization responsible for providing guidance and recommendations to help prevent disease and protect public health.

Ultra-Low Volume (ULV) Misting

An application method that produces very small disinfectant droplets using specialized equipment. ULV misting is one of several technologies used to distribute disinfectants over environmental surfaces.

This White Paper is part of the CleanSmart Resource Library, which provides evidence-based educational resources and technical publications on hypochlorous acid, cleaning, disinfection, and infection prevention.

Appendix B – Evidence Supporting Each Section

This appendix identifies the principal scientific, regulatory, and public health sources supporting each section of this white paper. Sources are organized according to the section they primarily support and are listed alphabetically within each section. It is intended to assist readers who wish to verify the evidence supporting the paper's conclusions and to locate the original reference material for further review.

Section 2.1 – The Importance of Environmental Disinfection in Daycare Facilities

The following government and public health publications support the discussion of routine environmental cleaning and disinfection practices in licensed daycare facilities.

Alberta Health Services. Health and Safety Guide for Operators of Child Care Facilities. View publication

Supports recommended environmental cleaning, sanitation, and infection prevention practices in licensed childcare facilities. 

Niagara Region Public Health. Cleaning and Disinfection (Child Care Manual). View publication

Supports operational guidance for routine cleaning and environmental disinfection in licensed childcare programs.

Northwestern Health Unit. Cleaning Protocols for Schools and Child Care Settings. View publication

Supports public health recommendations for routine environmental cleaning and disinfection in schools and childcare settings.

Ottawa Public Health. Environmental Cleaning and Disinfection in Child Care Centres and Schools. View publication

Supports evidence-based environmental cleaning and disinfection practices in childcare centres and schools.

Public Health Ontario. Child Care Centre Cleaning and Disinfection Schedule. View publication

Supports recommended cleaning and disinfection frequencies for toys, diapering areas, washrooms, food-contact surfaces, and other high-touch surfaces in licensed childcare centres.

Section 2.2 – Why Hypochlorous Acid Is an Effective Disinfectant

The following scientific publications support the discussion of hypochlorous acid as a broad-spectrum disinfectant, including its antimicrobial activity, safety profile, and practical applications.

Hypochlorous Acid as a Potential Wound Care Agent: Part 1. Stabilized Hypochlorous Acid—A Component of the Inorganic Armamentarium of Innate Immunity. View publication

Supports the discussion of the chemistry, antimicrobial activity, and biological role of stabilized hypochlorous acid.

Hypochlorous Acid as a Potential Wound Care Agent: Part 2. Stabilized Hypochlorous Acid—Its Role in Decreasing Tissue Bioburden and Overcoming the Inhibition of Infection on Wound Healing. View publication

Supports the discussion of microbial reduction, biofilm control, and the practical antimicrobial performance of stabilized hypochlorous acid.

Hypochlorous Acid: An Ideal Wound Care Agent with Powerful Microbicidal, Antibiofilm, and Wound Healing Potency. View publication

Supports the discussion of hypochlorous acid as a broad-spectrum antimicrobial with favourable safety, efficacy, and material compatibility characteristics.

World Health Organization. Hypochlorous Acid (HOCl) – Expert Committee on the Selection and Use of Essential Medicines. View publication

Supports the discussion of the chemistry, antimicrobial activity, safety profile, and healthcare applications of hypochlorous acid.

Section 2.3 – Understanding Hypochlorous Acid Fogging

The following government, public health, and technical publications support the discussion of fogging, electrostatic spraying, ULV misting, and related disinfectant application technologies.

Centers for Disease Control and Prevention. Safety Precautions When Using Electrostatic Sprayers and Foggers. View publication

Supports the discussion of electrostatic sprayers and foggers, including aerosol generation, operator safety, ventilation, and appropriate application practices.

Infection Control Handbook for Schools. Appendix G – Disinfectant Application Equipment. View publication

Supports the discussion of disinfectant application technologies, including manual spraying, electrostatic spraying, fogging, and ULV application equipment.

National Collaborating Centre for Environmental Health. COVID-19 in Indoor Environments: Air and Surface Disinfection Measures. View publication

Supports the discussion of air and surface disinfection technologies, including fogging and other whole-room application methods used as adjuncts to routine environmental cleaning.

Public Health Ontario. COVID-19: Electrostatic Spray Disinfection Systems (Frequently Asked Questions). View publication

Supports the discussion of electrostatic spraying technology, including operating principles, surface coverage, contact time, and practical limitations.

United States Environmental Protection Agency. Can I Use Fogging, Fumigation, or Electrostatic Spraying to Help Control COVID-19? View publication

Supports the discussion of fogging, fumigation, and electrostatic spraying by distinguishing these application methods and explaining their intended uses and limitations.

United States Environmental Protection Agency. Instructions for Adding Electrostatic Spray Application Directions for Use to Antimicrobial Product Registrations. View publication

Supports the discussion of electrostatic spraying by describing the method-specific performance expectations and supporting evidence required for disinfectant application technologies.

Section 2.4 – Scientific Evidence Supporting Hypochlorous Acid Fogging

The following peer-reviewed scientific publications support the discussion of hypochlorous acid delivered through fogging, dry fogging, whole-room atomization, and related automated disinfectant application technologies.

Evaluation of Liquid- and Fog-Based Application of Hypochlorous Acid Solution for Surface Inactivation of Human Norovirus. View publication

Supports the discussion of fog-based hypochlorous acid application for reducing human norovirus contamination on environmental surfaces under controlled laboratory conditions.

Impact of a Whole-Room Atomizing Disinfection System on Healthcare Surface Contamination, Pathogen Transfer, and Labor Efficiency. View publication

Supports the discussion of whole-room hypochlorous acid atomization as an adjunct to routine cleaning by demonstrating significant reductions in environmental microbial contamination and cross-contamination.

Inactivation of SARS-CoV-2 and Influenza A Virus by Dry Fogging Hypochlorous Acid Solution and Hydrogen Peroxide Solution. View publication

Supports the discussion of dry-fog hypochlorous acid by demonstrating effective inactivation of SARS-CoV-2 and Influenza A virus on environmental surfaces under controlled laboratory conditions.

Section 2.5 – Selecting a High-Quality Hypochlorous Acid Disinfectant

The following scientific and regulatory publications support the discussion that the performance of a hypochlorous acid disinfectant depends upon product formulation, stability, manufacturing quality, and regulatory oversight.

Health Canada. Drug Product Database (DPD). View publication

Supports the discussion of Health Canada-authorized disinfectant products, including Drug Identification Numbers (DINs), approved manufacturers, and authorized product information.

Health Canada. Guidance Document: Disinfectant Drugs. View publication

Supports the discussion of product quality, manufacturing consistency, stability, efficacy requirements, and scientific evidence required for Health Canada authorization.

Hypochlorous Acid (HOCl) – World Health Organization Expert Committee on the Selection and Use of Essential Medicines. View publication

Supports the discussion of hypochlorous acid chemistry, stability, formulation characteristics, and factors that influence product performance.

Section 2.6 – Health Canada and the Canadian Regulatory Framework

The following Canadian legislation, regulations, and Health Canada publications support the discussion of the federal regulatory framework governing disinfectant products and Health Canada's role in authorizing hypochlorous acid disinfectants.

Biocides Regulations (SOR/2024-110) (2024). View publication

Supports the discussion of Canada's regulatory framework governing biocide authorization, labelling, post-authorization changes, and manufacturer obligations.

Food and Drugs Act (R.S.C., 1985). View publication

Supports the discussion of the legislative authority governing the manufacture, sale, and regulation of disinfectant products in Canada.

Food and Drug Regulations (C.R.C., c. 870) (1978). View publication

Supports the discussion of regulatory requirements governing disinfectant authorization, approved labelling, and manufacturer compliance obligations.

Health Canada. Guidance Document: Disinfectant Drugs. View publication

Supports the discussion of Health Canada's scientific and regulatory requirements for authorizing disinfectant products, including efficacy, product quality, manufacturing standards, and approved directions for use.

Health Canada. Guidance on Labelling Requirements for Biocides: Inner and Outer Labels. View publication

Supports the discussion of Health Canada's requirements for approved product labels, including directions for use, precautionary statements, and manufacturer responsibilities.

Health Canada. Post-Authorization Guidance for Biocides. View publication

Supports the discussion of regulatory pathways for post-authorization changes, including amendments affecting approved labels, authorized claims, and supporting scientific evidence.

Health Canada. Transition to the Biocides Regulatory Framework. View publication

Supports the discussion of the transition of existing Drug Identification Number (DIN) disinfectants to the Biocides Regulations and the continuing obligations of authorization holders.

Section 2.7 – Practical Implementation Considerations

The following legislation, public health guidance, and operational references support the discussion of implementing hypochlorous acid disinfection safely and effectively within licensed daycare facilities.

Alberta Health Services. Health and Safety Guide for Operators of Child Care Facilities. View publication

Supports the discussion of routine environmental hygiene, operator responsibilities, infection prevention practices, and the use of approved disinfectants within licensed childcare facilities.

Ontario. Child Care and Early Years Act, 2014. View publication

Supports the discussion of operator responsibilities for protecting the health and safety of children within licensed childcare facilities.

Ontario Regulation 137/15 – General. View publication

Supports the discussion of licensing requirements and operational standards applicable to licensed childcare centres in Ontario.

Ontario Ministry of Education. Child Care Centre Licensing Manual. View publication

Supports the discussion of operational expectations, inspection practices, sanitation requirements, and regulatory compliance within licensed childcare centres.

Ottawa Public Health. Environmental Cleaning and Disinfection in Child Care Centres and Schools. View publication

Supports the discussion of practical environmental cleaning and disinfection procedures applicable to childcare facilities.

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