Systems and methods for air disinfection using formulations comprising organic acids

Abstract

Systems and methods for air disinfection. The system includes a device configured to produce atomized droplets of an antimicrobial agent having an average particle size sufficiently small such that the agent provides at least 3 logarithmic reduction of Staphylococcus aureus or another target microorganism within 60 minutes. The antimicrobial formulations comprise one or more organic acids (e.g., lactic acid) and optionally one or more glycols (e.g., 1, 2-hexanediol). The organic acid and the diol may have a vapor pressure of at least 0.02 Pa in the event both are included. If only the organic acid is contained, the organic acid has a vapor pressure of at least 0.10 Pa. The formulation may also include a buffer, a surfactant, water, perfume, etc. The formulations may be delivered as aerosols using pump sprayers, mist sprayers, nebulizers, evaporators, cold mist machines, hot mist machines, ultrasonic dispensing devices, electrostatic sprayers, and the like.

Description

Cross - Reference to Related Applications

[0001] This application claims the priority of U.S. Utility Patent Application Serial No. 18 / 528,419, filed on December 4, 2023, and claims the benefit and priority of U.S. Provisional Patent Application Serial No. 63 / 386,268, titled "SYSTEMS AND METHODS FOR AIR SANITIZATION USING FORMULAS CONTAINING AN ORGANIC ACID", filed on December 6, 2022. The disclosures of the above - mentioned patent applications are incorporated herein by reference in their entirety. BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention The present invention relates to air disinfection systems for use against airborne bacteria and / or viruses. Such systems can include formulations for delivery by any of a variety of mechanisms, including but not limited to aerosol sprayers, misters, pump sprayers, HVLP sprayers, ULV foggers, thermal foggers, electrostatic sprayers, and / or ultrasonic dispensing devices.

[0003] 2. Description of the Related Art Disinfectant sprays are commercially available. However, most of these sprays are intended to be sprayed to provide disinfection of a variety of surfaces. Examples of such include CLOROX DISINFECTING MIST and LYSOL DISINFECTANT SPRAY. Disinfectant foggers are also available, which are capable of airborne disinfection. However, these devices are generally complex and expensive and can result in long - term exposure to toxic chemicals. While disinfectant sprays and disinfectant foggers have shown some success in providing disinfection or sterilization, there is a continuing need for improved systems that will provide disinfection or sterilization of airborne bacteria and viruses in a safe, effective, and economical manner. BRIEF SUMMARY

[0004] The present disclosure relates to systems for air disinfection or sterilization, and related methods for providing air disinfection or sterilization. Current disinfection agents typically sterilize surfaces. However, there is a growing need to reduce such viruses and bacteria while they are still airborne, rather than waiting for such pathogens to reach a surface or come into contact with an animal or human host. When developing new disinfection or sterilization agents and systems, it is helpful to consider a variety of factors. For example, in an embodiment, the agent will include only components identified as "green circle" components (e.g., those that meet the EPA's DfE program) in the EPA's Safer Chemical Ingredients list. Additionally, in an embodiment, the active components of the agent should have a minimum threshold vapor pressure in order to remain airborne for a sufficient period of time to provide the desired disinfection or sterilization. Further, in an embodiment, the agent will have a long-term inhalation threshold acceptable to the general population by the European Chemicals Agency (ECHA) or a similar regulatory body. Additionally, the agent will of course need to provide significant antimicrobial properties while airborne (e.g., a significant log reduction of the target microorganisms, such as a 3-log reduction). Additionally, a device that produces droplets with an average particle size less than about 200 μm, less than about 150 μm, or less than about 100 μm can be used to atomize the agent into droplets. Finally, consumer preferences can be accommodated, such as including fragrances, ease of use, and non-toxicity. Embodiments of the inventive agent can provide antimicrobial efficacy against bacteria, viruses, and / or fungi present in the air as well as on hard surfaces, soft surfaces, and non-porous surfaces.

[0005] In one aspect, the present invention relates to a system for air disinfection that includes a device configured to produce atomized droplets of an antimicrobial agent, the atomized droplets having an average particle size small enough to permit air disinfection (e.g., less than about 200 μm, less than about 150 μm, less than about 100 μm, such as from about 5 μm to about 60 μm), wherein the antimicrobial agent includes one or more organic acids. In some embodiments, one or more diols may also be present. In an embodiment, the organic acid has a vapor pressure of at least 0.1 Pa, at least 0.15 Pa, at least 0.2 Pa, at least 0.25 Pa, at least 0.3 Pa, at least 0.35 Pa, or at least 0.40 Pa, such as from 0.10 Pa to about 300 Pa, under standard conditions (20 °C and 1 atm). When both one or more organic acids and one or more diols are present, the organic acid and the diol may be selected to have a vapor pressure of at least 0.02 Pa specifically at room temperature (e.g., standard conditions). Also contemplated is a related method of use for such a system. Any component (such as such organic acids and / or diols) or other components present in a significant fraction (e.g., greater than 0.1%, greater than 0.2%, greater than 0.5%, or greater than 1%) may have at least 10 mg / m3 or at least 20 mg / m 3 long-term inhalation threshold limit value for the general population of ECHA or similar.

[0006] In an embodiment, exemplary organic acids providing such properties include lactic acid, and an exemplary diol can be 1,2 - hexanediol. In an embodiment, the diol can consist of 1,2 - hexanediol (rather than a mixture of different diols).

[0007] In an embodiment, the antimicrobial preparation can contain from 0.1% to 5% (e.g., about 2%) lactic acid.

[0008] In an embodiment, the antimicrobial preparation can contain from 0.5% to 10% (e.g., about 4% - 5%) 1,2 - hexanediol.

[0009] In an embodiment, the pH of the antimicrobial preparation can be from about 1.5 to about 6, from about 2 to about 5, from about 2 to about 4, from about 2 to about 3, from about 2 to about 2.5, or from about 2.0 to about 2.4.

[0010] In an embodiment, the diol and the organic acid can be included relative to each other in a specific ratio (e.g., 3:1 to 1:3). In an embodiment, the diol is included in a greater concentration than the organic acid. For example, the concentration ratio of the diol (e.g., 1,2 - hexanediol) to the organic acid (e.g., lactic acid) can be from about 1:1 to about 4:1, from about 1.2:1 to about 4:1, from about 1.5:1 to about 3.5:1, or from about 1.5:1 to about 2.5:1. In another embodiment, lactic acid can be dominant, such as where the ratio of lactic acid to the diol is greater than 1, such as from about 1.1 to about 2:1, or from about 1:1 to about 1.5:1, or from about 1:1 to about 1.3:1 (e.g., about 1.1). The specific concentration and / or ratio of 1,2 - hexanediol or other diols to lactic acid or other organic acids can be an important means (lever), and even a crucial means in some embodiments, to achieve the desired air disinfection. The average particle size provided by the dispensing device (e.g., less than about 200 μm, less than 150 μm, less than 100 μm, less than 80 μm, less than about 60 μm, such as from about 5 μm to about 60 μm) can also be an important, and even crucial, property.

[0011] In an embodiment, the antimicrobial preparation can contain a buffering agent, such as citric acid, present, for example, from about 0.1% to about 5%.

[0012] In an embodiment, the antimicrobial preparation can further contain a surfactant and / or a fragrance.

[0013] In an embodiment, the antimicrobial formulation can provide at least a 3-log reduction, a 4-log reduction, or a 5-log reduction (e.g., at least a 3.0-log reduction) of an airborne target virus or other microorganism (e.g., Staphylococcus aureus ( Staphylococcus aureus )) in 60 minutes or less (e.g., sometimes even in 30 minutes, or in 10 minutes).

[0014] In an embodiment, the formulation can be free or substantially free of: propylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, other diols including ether groups, hypochlorite, ethanol, isopropanol, 1-propanol, 1-hexanol, and / or resorcinol.

[0015] In another aspect, the system includes a device configured to produce atomized droplets of an antimicrobial formulation having an average particle size small enough (e.g., less than about 200 μm, less than about 150 μm, less than about 100 μm, less than about 80 μm, less than about 60 μm, such as from about 5 μm to about 60 μm), wherein the formulation comprises at least one of lactic acid or citric acid in an amount of about 0.1% to about 5% by weight; 1,2-hexanediol in an amount of about 0.5% to about 10% by weight; at least one of a fragrance or a surfactant; and at least 80% water by weight. In an embodiment, both lactic acid and citric acid can be present in a range of about 0.1% to about 5% by weight. In such an embodiment, the antimicrobial formulation can have a pH from 2 to 4 and can provide at least a 3-log reduction of an airborne target microorganism in 60 minutes.

[0016] In another aspect, the system includes a device configured to produce atomized droplets of an antimicrobial formulation having a relatively small average particle size as described herein, wherein the formulation comprises about 0.1% to about 5% lactic acid by weight, about 0.5% to about 10% 1,2-hexanediol by weight, optionally about 0.1% to about 5% citric acid by weight, a fragrance, a surfactant, or another desired adjuvant, and at least 80% water by weight. In such an embodiment, the antimicrobial formulation can have a pH from about 2 to about 4 and can provide at least a 3-log reduction of an airborne target microorganism (e.g., Staphylococcus aureus) in 60 minutes or less.

[0017] Another aspect relates to a method for providing air disinfection treatment, wherein the method comprises providing an antimicrobial preparation, the antimicrobial preparation comprising, for example, one or more organic acids such as lactic acid at about 0.1% to about 5% by weight, optionally a diol such as 1,2 - hexanediol at about 0.5% to 10% by weight, and at least 80% by weight of water, wherein the preparation has a pH as described herein, for example, a pH from about 2 to about 4, provides at least a 3 - log reduction of airborne target microorganisms within 60 minutes or less, and is delivered as a mist to the air to be disinfected. The preparation can be delivered using a fine - mist sprayer, a pump - type sprayer, an atomizer, an evaporator, a cold - fog machine, a hot - fog machine, an ultrasonic dispensing device (e.g., an ultrasonic diffuser), an electrostatic sprayer, a combination thereof, or other delivery methods. In an embodiment, the preparation can be a two - part preparation, wherein the delivery of the antimicrobial preparation is step - wise, wherein any diol (e.g., 1,2 - hexanediol) is delivered first, and lactic acid or other organic acid is delivered second.

[0018] In an embodiment, the total molar amount of lactic acid or other organic acid and 1,2 - hexanediol or other diol delivered to the air to be disinfected is from about 0.1 mmol / m 3 to about 4 mmol / m 3 or from about 0.1 mmol / m 3 to about 2 mmol / m 3 . mmol / m 3 Values can be calculated based on the assumption that all chemicals are completely evaporated into the gaseous form. Thus, such calculated values may be overestimated relative to empirical values. The empirical value of the total molar amount of lactic acid or other organic acid and 1,2 - hexanediol or other diol delivered to the air to be disinfected can be, for example, from about 0.05 mmol / m 3 to about 1.5 mmol / m 3 .

[0019] In an embodiment, the selected organic acid has a vapor pressure in the range from 0.10 Pa to about 300 Pa, or from 0.10 Pa to about 200 Pa, from 0.40 Pa to about 300 Pa, from 0.40 Pa to about 200 Pa, from 0.41 Pa to about 172 Pa, or from about 5 Pa to about 300 Pa, or from about 5 Pa to about 200 Pa under standard conditions (room temperature and 1 atm).

[0020] In an embodiment, the selected organic acid has a water solubility of at least about 10 g, at least about 20 g, at least about 24.99 g, such as from about 10 g to about 100 g, about 10 g to about 50 g, or about 20 g to about 50 g of the organic acid per 100 grams of water under standard conditions (room temperature and 1 atm).

[0021] Additional features and advantages of the invention will become apparent to those of ordinary skill in the art upon a detailed description of the preferred embodiments below. Brief Description of the Drawings

[0022] To further clarify the above and other advantages and features of the present invention, a more specific description of the invention will be presented by reference to specific embodiments of the invention illustrated in the accompanying drawings that are located in the specification. It should be understood that these drawings only depict typical embodiments of the invention and should not be considered as limiting its scope. The invention will be described and explained with additional features and details by using the drawings.

[0023] Figure 1 The log reduction of airborne Staphylococcus aureus over time using different doses of Prototype #1 (4.25% 1,2 - hexanediol, 2% lactic acid) is plotted. The log reduction is normalized relative to an untreated baseline.

[0024] Figure 2 The log reduction of airborne MS2 over time using different doses of Prototype #1 (4.25% 1,2 - hexanediol, 2% lactic acid) is plotted. The log reduction is normalized relative to an untreated baseline.

[0025] Figure 3 The normalized log reduction (per g / m 3 log reduction of the delivered formulation) of phi 6 for various formulations including lactic acid and 1,2 - hexanediol at a 10 - minute exposure time is plotted relative to the mole fraction of 1,2 - hexanediol relative to the molar concentration of the formulation delivered to the treatment space (mmol / m 3 ). The tests were conducted in a 1 m 3 air chamber delivered via a nebulizer, where Dv50 was approximately 70 µm.

[0026] Figure 4 The log reduction of phi 6 at different mole fraction ratios of 1,2 - hexanediol and lactic acid at a 60 - minute exposure time is plotted. The total concentration of 1,2 - hexanediol and lactic acid was kept constant at 254 mmol, 582 mmol, and 1164 mmol, and the log reduction was normalized relative to an untreated baseline. The tests were conducted in a 1 m 3It is carried out in a gas chamber, where 1 g of the chemical substance is delivered via a nebulizer, and Dv50 is about 70 µm.

[0027] Figure 5 The figure shows the log reduction of phi 6 with 3.5% 1,2 - hexanediol and different levels of lactic acid. The log reduction is normalized relative to the untreated baseline.

[0028] Figure 6 The log reduction over time was plotted for prototype #1 (4.25% 1,2 - hexanediol, 2% lactic acid) and a prototype containing equal amounts of lactic acid in acid form and 4.25% HDO after pH adjustment with and without a citrate buffer. The log reduction is normalized relative to the untreated baseline. The test was carried out in a 1 m 3 gas chamber, where Dv50 is about 70 µm.

[0029] Figure 7 The log reduction (log reduction / g of the delivered formulation) of prototype #1 (4.25% 1,2 - hexanediol, 2% lactic acid) over time was plotted for multiple delivery methods, which include step - release 1 (first HDO), step - release 2 (first LA), and separate but simultaneous release of the lactic acid and 1,2 - hexanediol components of the antimicrobial formulation. The log reduction is normalized relative to the untreated baseline. Step - release involves releasing one chemical substance first, followed by delivering the second chemical substance after 2 minutes. Separate release involves simultaneously releasing two chemical substances from different reservoirs at different positions within an enclosed volume. The test was carried out in a 1 m 3 gas chamber, where Dv50 is about 70 µm.

[0030] Figure 8 The log reduction of prototype #1 (4.25% 1,2 - hexanediol, 2% lactic acid) against Staphylococcus aureus was plotted based on the particle size using multiple sprays. The test was carried out in a 1 m 3 gas chamber.

[0031] Figure 9 The log reduction of prototype #1 (4.25% 1,2 - hexanediol, 2% lactic acid) against Staphylococcus aureus and Klebsiella pneumoniae ( Klebsiella pneumoniae ) was plotted on a soft cotton surface with a 5 - minute exposure time.

[0032] Figure 10The log reduction of airborne phi 6 was plotted for multiple formulations, including formulations containing individual organic acids (e.g., lactic acid), formulations containing individual diols (e.g., 1,2 - hexanediol), and formulations containing both an organic acid and a diol together, showing synergistic results associated with including both an organic acid and a diol. The tests were conducted in a 1 m 3 chamber with a Dv50 of approximately 70 µm via a nebulizer. The log reduction shown was plotted against an untreated baseline.

[0033] Figure 11 The log reduction of airborne phi 6 by such organic acids was plotted for multiple vapor pressures of multiple organic acids. The tests were conducted in a 1 m 3 chamber with a Dv50 of approximately 70 µm via a nebulizer. For each test, 2 g of 222 mmol of the organic acid was delivered. The log reduction shown at a 15 - minute contact time was plotted against an untreated baseline. Multiple organic acids with vapor pressures from 0.41 Pa to 172 Pa showed at least 3 log reductions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] I. DEFINITIONS Before describing the invention in detail, it is to be understood that the invention is not limited to the specifically exemplified systems or process parameters, which may of course vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of the invention only and is not intended to limit the scope of the invention in any way.

[0035] All publications, patents, and patent applications cited herein, whether above or below, are hereby incorporated by reference in their entirety to the extent that each individual publication, patent, or patent application is specifically and individually indicated to be incorporated by reference.

[0036] The term "comprising", which is synonymous with "including", "containing", or "characterized by", is inclusive or open - ended and does not exclude additional, unrecited elements or method steps.

[0037] The term "consisting essentially of" limits the scope of a claim to the specified materials or steps and those materials or steps that "do not materially affect the basic and novel characteristics" of the claimed invention.

[0038] The term "consisting of" as used herein excludes any element, step, or ingredient not specified in the claim.

[0039] It should be noted that, as used in this specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" include plural referents. Thus, for example, reference to "a surfactant" includes one, two, or more surfactants.

[0040] Unless otherwise stated, all percentages, ratios, parts, and amounts used and described herein are by weight.

[0041] As will be understood by those of ordinary skill in the art, the numbers, percentages, ratios, or other values recited herein may include that value and also other values that are about or approximate the recited value. Accordingly, all values herein are understood to be modified by the term "about". Such values thus include amounts or states that are close to the recited amount or state and that still perform the desired function or achieve the desired result. Accordingly, the recited values should be interpreted broadly enough to encompass at least values that are close enough to the recited value to perform the desired function or achieve the desired result, and / or values that round to the recited value. The recited values include at least the variations expected in typical manufacturing or other processes and may include values within 10%, 5%, 1%, etc. of the recited value.

[0042] Some ranges may be disclosed herein. Additional ranges may be defined between any values that are recited as examples of a particular parameter. All such ranges are contemplated and are within the scope of this disclosure.

[0043] As used herein, the term "between" includes any endpoint recited with respect to the described range.

[0044] In this application, an effective amount is generally those amounts that are listed as a range or level of a component in the subsequent description. Unless otherwise stated, amounts listed as a percentage ("%") are by weight percentage of any composition (based on 100% of the active substance).

[0045] If used herein, the phrase "free of" or similar phrase means that the composition or article contains 0% of the recited component, i.e., the component is not intentionally added. However, it will be understood that in some cases, such a component may form incidentally later, or such a component may be present incidentally, such as being present as an incidental contaminant.

[0046] As used herein, the phrase "substantially free of" or similar phrases means that the composition or article preferably contains 0% of the stated component, although it should be understood that very small concentrations may be present, for example, by accidental formation, contamination, or even by intentional addition. If present, such a component may be present in an amount less than 1%, less than 0.5%, less than 0.25%, less than 0.1%, less than 0.05%, less than 0.01%, less than 0.005%, less than 0.001%, or less than 0.0001%. In some embodiments, the compositions or articles described herein may be free of or substantially free of any particular component not mentioned in this specification.

[0047] The antimicrobial agents described herein can provide disinfection, bactericidal, or sterilization, other cleaning, or other treatment. As used herein, the term "sanitize" shall mean reducing the "target" contaminants in an inanimate environment to a level of at least 3 logs below the untreated condition, or reducing the "target" bacterial population by a significant number in cases where public health requirements have not been established. By way of example, a reduction of at least 99% of the bacterial population within a 24-hour period is considered "significant". Higher levels of reduction (e.g., 99.9%, 99.99%, etc.) are possible when disinfecting or bactericidal, and faster treatment times (e.g., within 10 minutes, within 5 minutes, within 4 minutes, within 3 minutes, within 2 minutes, within 1 minute, or within 30 seconds) are also possible.

[0048] As used herein, the term "disinfect" shall mean eliminating at least 6 logs of many or all "target" pathogenic microorganisms other than bacterial endospores on a surface.

[0049] As used herein, the term "sterilization" shall mean completely eliminating or destroying all forms of "target" microbial life, and things authorized by applicable regulatory laws to legally claim as "sterilants" or having sterilizing properties or qualities.

[0050] Some embodiments can provide at least a 2 or more log reduction of a bacterial population (e.g., 3 log reduction, 4 log reduction, 5 log reduction, or 6 log reduction) relative to a baseline over a specified time period (e.g., 10 minutes, 5 minutes, 4 minutes, 3 minutes, 2 minutes, 1 minute, 30 seconds, or similar times). A 2 log reduction is equivalent to a 99% reduction, a 3 log reduction is equivalent to at least a 99.9% reduction, a 4 log reduction is equivalent to at least a 99.99% reduction, a 5 log reduction is equivalent to at least a 99.999% reduction, and so on. Examples of target microorganisms can be Staphylococcus aureus. It should be understood that antimicrobial efficacy against other target microorganisms can also be achieved, and many examples of other target microorganisms will be apparent to those skilled in the art.

[0051] The term "Design for the Environment" or "DfE" refers to a U.S. EPA program that focuses on identifying safer disinfecting and sanitizing active ingredients. The EPA has a special approval process for products that meet DfE criteria. As part of the DfE program, the EPA has identified certain active ingredients that are approved for use in antimicrobial cleaning products and are authorized to use the DfE logo. Antimicrobial cleaning products that have been approved under the DfE program can be found at https: / / www.epa.gov / pesticide-labels / design-environment-logo-antimicrobial-pesticide-products#authorizeddfe. All DfE program-approved products must have ingredients that meet the "Safer Choice Standard" according to https: / / www.epa.gov / pesticide-labels / design-environment-logo-antimicrobial-pesticide-products#approved. In embodiments, the compositions of the present invention can be formulated to meet DfE guidelines or similar regulatory guidelines.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although many methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.

[0053] II. Exemplary Air Disinfection Systems and Formulations In aspects, the present invention relates to a system comprising an antimicrobial agent for use in air disinfection treatment. Additionally, the present disclosure relates to methods for providing such treatment. For effective air disinfection, the antimicrobial agent should have atomized antimicrobial agent droplets, where antimicrobial molecules can leave the atomized droplets (due to droplet size and their vapor pressure) and affect airborne microbial targets. Microbial targets can include both enveloped viruses (e.g., phi 6, SARS-Covid surrogate) and non-enveloped viruses (e.g., MS2), as well as other pathogenic bacteria or fungi (e.g., Staphylococcus aureus, Aspergillus niger( A. niger ), Klebsiella pneumoniae, Pseudomonas aeruginosa( Pseudomonas aeruginosa ), etc.).

[0054] A. Organic Acids and Diols Embodiments of the antimicrobial agent comprise at least one organic acid and optionally at least one diol. In an embodiment, the organic acid has a vapor pressure in the range from 0.10 Pa to about 300 Pa at room temperature (e.g., 20 °C), standard conditions (e.g., 1 atm). In cases where both the organic acid and the diol are included, the organic acid and the diol in the antimicrobial agent can have a vapor pressure of at least 0.02 Pa at room temperature standard conditions. In an embodiment, the organic acid, any diol, and any other components present in relatively high concentrations can have a long-term inhalation threshold limit value for the general population of at least 10 mg / m 3 of the European Chemicals Agency (ECHA). It will be apparent that various components included in very small amounts (e.g., not more than 1%, not more than 0.5%, or not more than 0.1%) may not need to meet such limits.

[0055] In an embodiment, the organic acid is a short-chain organic acid, such as having no more than about 12, no more than about 10, no more than about 8, no more than about 6, or no more than about 4 carbon atoms. In an embodiment, the organic acid is a mono-organic acid (e.g., as opposed to a dicarboxylic acid or polycarboxylic acid). In an embodiment, when included, the diol is a short-chain diol, such as having no more than about 16, no more than about 12, no more than about 10, no more than about 8, no more than about 6, or no more than about 4 carbon atoms. In an embodiment, the organic acid is lactic acid or includes lactic acid, and the diol is 1,2-hexanediol or includes 1,2-hexanediol. Based on the weight of the antimicrobial agent, lactic acid or other organic acids may be included in an amount from about 0.05%, from about 0.1%, about 0.5%, from about 1%, from about 1.5%, from about 2%, up to about 10%, up to about 8%, up to about 6%, up to about 5%, up to about 4%, or up to about 3%. In an embodiment, lactic acid is included in an amount of about 2% by weight of the antimicrobial agent. Based on the weight of the antimicrobial agent, 1,2-hexanediol or other diols may be included in an amount from about 0.05%, from about 0.1%, from about 0.5%, from about 1%, from about 2%, from about 3%, from about 4%, up to about 15%, up to about 12%, up to about 10%, up to about 8%, up to about 7%, up to about 6%, or up to about 5%. In an embodiment, 1,2-hexanediol or other diols are included in an amount of about 4.25% by weight of the antimicrobial agent. It should be understood that concentrates may also be possible, such as providing lactic acid, other organic acids, and / or 1,2-hexanediol or other diol concentrations of up to about 70%, up to about 60%, up to about 50%, up to about 40%, up to about 30%, or up to about 20%, which, for example, will be diluted to the more dilute values mentioned above upon delivery.

[0056] In an embodiment, the concentration ratio of 1,2-hexanediol or other diols to lactic acid or other organic acids is from about 3:1 to about 1:3, or in an embodiment, it may be greater than 1:1, such as from about 1.2:1 to about 4:1, or from about 1.5:1 to about 3.5:1, or from about 1.5:1 to about 2.5:1 (e.g., about 2:1). In another embodiment, lactic acid may be dominant, such as where the ratio of lactic acid to diol is greater than 1, such as from about 1.1 to about 2:1, or from about 1:1 to about 1.5:1, or from about 1:1 to about 1.3:1 (e.g., about 1.1). Such concentrations, ratios, and the average airborne droplet size provided by the system of the present invention may be important, even critical, characteristics for achieving the air disinfection characteristics described herein.

[0057] In embodiments, two or more diols can be provided. Similarly, two or more organic acids can be provided. In another embodiment, only a single diol is provided (e.g., the diol consists of 1,2 - hexanediol). In embodiments, only a single organic acid is provided (e.g., the organic acid consists of lactic acid). Non - limiting examples of organic acids include maleic acid, methanesulfonic acid, benzoic acid, levulinic acid, glycolic acid, lactic acid, pyruvic acid, propionic acid, and / or acetic acid. Organic acids that exhibit a vapor pressure in the range of from 0.10 Pa to about 300 Pa or from 0.40 Pa to 200 Pa under standard conditions may be particularly desirable. Such examples include, but are not limited to, glycolic acid, lactic acid, and pyruvic acid.

[0058] In another aspect, the pH of the antimicrobial formulation is maintained low. A low pH can be important for lactic acid or other acids to achieve air disinfection efficacy. Lactic acid is most effective in its acid form compared to the conjugate base form (lactate). For example, the acid form of lactic acid is more volatile. At a pH of 2.2, at least 95% of the present lactic acid is in the acidic form (lactic acid has a pK a )). While lactic acid has higher efficacy at low pH, neutral pH formulations have better aesthetics and potentially lower toxicity. Thus, a pH that provides a balance between the microefficacy of lactic acid and the aesthetics and toxicity levels is desirable.

[0059] By way of example, the pH can be at least about 1, at least about 1.5, at least about 2, up to about 6.5, up to about 6, up to about 5, up to about 4, up to about 3, up to about 2, up to about 2.5, or up to about 2.4. In embodiments, the pH is maintained between about 2 and about 4, or between about 2 and about 3. The pH can be maintained by adding a buffer. In some embodiments, the buffer includes citric acid. It is important to note that citric acid is present as a buffer and not for any primary antimicrobial benefit. The citric acid buffer can be included in an amount of at least about 0.05%, at least about 0.1%, up to about 6%, up to about 5%, up to about 4%, up to about 3%, up to about 2%, up to about 1.5%, or up to about 1% by weight of the antimicrobial formulation.

[0060] B. Solvent In embodiments, the formulation can be free or substantially free of additional solvents other than the diol. That is, in other embodiments, solvents such as diol ether solvents can be present. Exemplary diol ether solvents include, but are not limited to, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol phenyl ether, propylene glycol n-propyl ether, propylene glycol monobutyl ether, propylene glycol tert-butyl ether, diethylene glycol monoethyl ether or diethylene glycol monopropyl ether or diethylene glycol monobutyl ether, dipropylene glycol methyl ether or tripropylene glycol methyl ether or dipropylene glycol ethyl ether or tripropylene glycol ethyl ether or dipropylene glycol propyl ether or tripropylene glycol propyl ether or dipropylene glycol butyl ether or tripropylene glycol butyl ether, acetates and / or propionates of the diol ethers. By weight of the formulation, it can contain from about 0.1%, from about 0.25%, up to about 5%, up to about 4%, up to about 3%, up to about 2% or up to about 1% of the diol ether or other solvents. Other solvents, surfactants and various other adjuvants that are commonly included in disinfectant formulations or bactericidal formulations can be optionally present. Although some embodiments can include lower alcohol solvents (e.g., C1-C4 monohydric alcohols), the amount of such volatile solvents can be limited to, for example, less than about 50%, less than about 40%, less than about 30%, less than about 20%, less than about 10%, less than about 5%, less than about 3%, less than about 2%, less than about 1%, less than about 0.5% or less than about 0.3% by weight. In some embodiments, the composition can be free or substantially free of such lower monohydric alcohols or other highly volatile solvents.

[0061] In embodiments, the antimicrobial formulation can be free or substantially free of diols other than hexylene glycol or even diol ethers. Examples of such diols include, but are not limited to, propylene glycol, dipropylene glycol, triethylene glycol and hexylene glycol. In embodiments, the composition can similarly be free or substantially free of resorcinol.

[0062] C. Surfactants In embodiments, the antimicrobial formulation can contain one or more surfactants (e.g., especially anionic surfactants and / or nonionic surfactants). In some embodiments, one or more surfactants can be included in an amount of at least about 0.025%, at least about 0.05%, at least about 0.1%, at least about 0.2%, at least about 0.3%, at least about 0.4%, at least about 0.5%, up to about 10%, up to about 3%, up to about 2% or up to about 1% by weight of the antimicrobial formulation.

[0063] Those skilled in the art will understand that, as needed, any one of a variety of surfactants (e.g., anionic surfactants, cationic surfactants, nonionic surfactants, zwitterionic surfactants, and / or amphoteric surfactants) can be included in the formulation. When included, the surfactant can be present in an amount from about 0.05%, from about 0.1%, up to about 10%, up to about 5%, up to about 4%, up to about 3%, up to about 2%, or up to about 1% by weight of the formulation. A variety of surfactants and other optional adjuvants are disclosed in U.S. Patent No. 3,929,678 to Laughlin and Heuring; U.S. Patent No. 4,259,217 to Murphy; U.S. Patent No. 5,776,872 to Giret et al.; U.S. Patent No. 5,883,059 to Furman et al.; U.S. Patent No. 5,883,062 to Addison et al.; U.S. Patent No. 5,906,973 to Ouzounis et al.; U.S. Patent No. 4,565,647 to Llenado, and U.S. Publication No. 2013 / 0028990. The above patents and applications are hereby incorporated by reference in their entirety.

[0064] Examples of nonionic surfactants include, but are not limited to, alcohol ethoxylates, alcohol propoxylates, other alcohol alkoxylates, including fatty (e.g., C6, C8, C 10 or C 12 or higher) alcohols or other components that have been alkoxylated to include both ethoxy and propoxy groups (EO-PO surfactants), alkyl phosphine oxides, alkyl glucosides and alkyl pentosides, alkyl glycerides, alkyl ethoxylates, and all types of alkyl ethoxylates and alkylphenol ethoxylates, polyalkoxylated (e.g., ethoxylated or propoxylated) C6-C 12 linear or branched alkylphenols, C6-C 22 linear or branched aliphatic primary or secondary alcohols, and C2-C8 linear or branched aliphatic diols. Block or random copolymers of C2-C6 linear or branched alkylene oxides can also be suitable nonionic surfactants. Capped nonionic surfactants in which the terminal hydroxyl group has been replaced with; halides; C1-C8 linear, branched, or cyclic aliphatic ethers; C1-C8 linear, branched, or cyclic aliphatic esters; phenyl ethers, benzyl ethers, or C1-C4 alkylaryl ethers; or phenyl esters, benzyl esters, or C1-C4 alkylaryl esters can also be used. Sorbitan esters and ethoxylated sorbitan esters can also be useful nonionic surfactants. Other suitable nonionic surfactants can include monoalkoxylated amides or polyalkoxylated amides of the formula R¹CONR²R³ and amines of the formula R¹NR²R³, where R¹ is C5-C 31a straight-chain or branched-chain alkyl group, and R 2 and R 3 are C1-C4 alkyl, C1-C4 hydroxyalkyl, or alkoxylated with 1-3 moles of straight-chain or branched-chain alkylene oxide. Biosoft 91-6 (Stepan Co.) is an example of an alkyl ethoxylate (or alcohol ethoxylate) having an average ethoxylation degree of 6 moles and a C9 to C 11 methylene chain length. An example of an alcohol ethoxylate is ECOSURF EH-9, which is more specifically the ethylene oxide-propylene oxide copolymer mono(2-ethylhexyl) ether available from Sigma-Aldrich.

[0065] Alkyl polysaccharide nonionic surfactants are disclosed in Llenado's U.S. Patent 4,565,647, which have a straight-chain or branched-chain alkyl group, an alkylphenyl group, a hydroxyalkyl group, or a hydroxyalkylphenyl group containing from about 6 to about 30 carbon atoms and a polysaccharide hydrophilic group containing from about 1.3 to about 10 sugar units such as a polyglycoside hydrophilic group. Suitable sugars can include, but are not limited to, glucosides, galactosides, lactosides, and fructosides. The alkyl polyglycoside can have the following formula: R 2 O(C n H 2n O) t (glycosyl) x , where R 2 is selected from the group consisting of alkyl, alkylphenyl, hydroxyalkyl, hydroxyalkylphenyl, and mixtures thereof, where the alkyl group contains from about 10 to about 18 carbon atoms; n is 2 or 3; t is from 0 to about 10, and x is from about 1.3 to about 10.

[0066] Fatty acid sugar esters and alkoxylated fatty acid sugar esters can also be suitable for use in the present invention. Examples include, but are not limited to, sucrose esters such as sucrose cocoate and sorbitan esters such as polyoxyethylene (20) sorbitan monooleate and polyoxyethylene (20) sorbitan monolaurate.

[0067] Phosphate ester surfactants can also be suitable. These include monoesters, diesters, and triesters of phosphoric acid with C4-C 18 alkyl, aryl, alkylaryl, alkyl ether, aryl ether, and alkylaryl ether alcohols (e.g., sodium dioctyl phosphate).

[0068] Amphoteric surfactants can be suitable. Since amphoteric surfactants include both positive and negative functional groups, they can also be classified as nonionic surfactants. Many such amphoteric surfactants contain nitrogen. Examples include amine oxides, sarcosinates, taurates, and betaines. Examples include C8-C 18Alkyl dimethylamine oxides (such as octyl dimethylamine oxide, lauryl dimethylamine oxide (also known as lauramine oxide), and cetyl dimethylamine oxide), C4-C 16 Dialkyl methylamine oxides (such as didecyl methylamine oxide), C8-C 18 Alkyl morpholine oxides (such as lauryl morpholine oxide), tetraalkyl diamine dioxides (such as tetramethylhexane diamine dioxide, lauryl trimethylpropane diamine dioxide), C8-C 18 Alkyl betaines (such as decyl betaine and cetyl betaine), C8-C 18 Acyl sarcosinates (such as sodium lauroyl sarcosinate), C8-C 18 Acyl C1-C6 alkyl taurates (such as sodium cocoyl methyl taurate), C8-C 18 Alkyliminodipropionates (such as sodium lauryliminodipropionate) and combinations thereof. Lauryl dimethylamine oxide (Ammonyx LO), myristyl dimethylamine oxide (Ammonyx MO), decylamine oxide (Ammonyx DO) are examples of suitable zwitterionic surfactants and are available from Stepan Co.

[0069] Non-limiting examples of anionic surfactants include alkyl sulfates (such as C8-C 18 linear or branched alkyl sulfates such as sodium lauryl sulfate (SLS) and sodium tetradecyl sulfate), linear alkylbenzene sulfonic acids or sulfonates (HLAS), alkyl sulfonates (such as C6-C 18 linear or branched alkyl sulfonates such as sodium octane sulfonate and secondary alkane sulfonates), alkyl ethoxysulfates, fatty acids and fatty acid salts (such as C6-C 16 fatty acid soaps such as sodium laurate) and alkyl amino acid derivatives. Other examples can include sulfate derivatives of the following: alkyl ethoxylate propoxylates, alkyl ethoxylate sulfates, alpha-olefin sulfonates, C6-C 16 acyl hydroxyethyl sulfonates (such as sodium cocoyl hydroxyethyl sulfonate), C6-C 18 alkyl, aryl or alkylaryl ether sulfates, C6-C 18 alkyl, aryl or alkylaryl ether methyl sulfonates, C6-C 18 alkyl, aryl or alkylaryl ether carboxylates, sulfonated alkyl diphenyl oxides (such as sodium dodecyl diphenyl oxide disulfonate) and the like.

[0070] More specific examples of nonionic surfactants and / or zwitterionic surfactants include lauryldimethylamine oxide (Ammonyx LO) (also known as lauramine oxide), myristyldimethylamine oxide (Ammonyx MO), decyldimethylamine oxide (Ammonyx DO), other amine oxides, any betaine, linear alcohol ethoxylates, secondary alcohol ethoxylates, alcohol propoxylates, alkyl polyglucosides, and combinations thereof.

[0071] D. Additional adjuvants The formulation may optionally include one or more additional adjuvants and / or be used in combination with one or more additional adjuvants. Adjuvants include, but are not limited to, fragrances or perfumes, waxes, dyes and / or colorants, solubilizing materials, stabilizers, thickeners, defoamers, hydrotropes, buffers, builders, detergents and / or mineral oils, enzymes, cloud point modifiers, and / or preservatives, and / or chaotropic agents. In one embodiment, when used, buffers and pH regulators include, but are not limited to, organic acids, inorganic acids, alkali metal salts and alkaline earth metal salts of citrates, silicates, metasilicates, polysilicates, borates, carbonates, carbamates, phosphates, polyphosphates, pyrophosphates, triphosphates, tetraphosphates, ammonia, hydroxides, monoethanolamine, monopropanolamine, diethanolamine, dipropanolamine, triethanolamine, and / or 2-amino-2-methyl-1-propanol.

[0072] Buffers can be low molecular weight organic or inorganic materials for maintaining the desired pH. For buffers that can be used, see McCutcheon's EMULSIFIERS AND DETERGENTS, North American Edition, 1997, McCutcheon Division, MC Publishing Company, which is incorporated herein by reference. In yet another embodiment and / or alternative embodiment, when used, solubilizing materials can include, but are not limited to, hydrotropes (e.g., water-soluble salts of low molecular weight organic acids such as sodium and / or potassium xylene sulfonates).

[0073] In still another embodiment and / or alternative embodiment, when used, thickeners include, but are not limited to, polyacrylic acid, xanthan gum, calcium carbonate, alumina, alginate, guar gum, methyl, ethyl, clay, and / or propyl hydroxycellulose. In yet another embodiment and / or alternative embodiment, when used, defoamers include, but are not limited to, silicone, amino silicone, silicone blends, and / or silicone / hydrocarbon blends. In still further embodiments and / or alternative embodiments, when used, preservatives include, but are not limited to, mildewstat or bacteriostat, methyl paraben, ethyl paraben, and propyl paraben, short-chain organic acids (such as acetic acid, lactic acid, and / or glycolic acid), biguanide compounds (such as Dantagard and / or Glydant), and / or short-chain alcohols (such as ethanol and / or IPA). In one aspect of this embodiment, the mildewstat or bacteriostat includes, but is not limited to, mildewstat (including non-isothiazolone compounds) including the following: Kathon GC, 5-chloro-2-methyl-4-isothiazolin-3-one, Kathon ICP, 2-methyl-4-isothiazolin-3-one and blends thereof, and Kathon 886, 5-chloro-2-methyl-4-isothiazolin-3-one, all of which are available from Rohm and Haas Company; Bronopol, 2-bromo-2-nitropropane-1,3-diol, from Boots Company Ltd.; Proxel CRL, propyl paraben, from ICI PLC; Nipasol M, sodium o-phenylphenate, from Nipa Laboratories Ltd.; Dowicide A, 1,2-benzisothiazolin-3-one, from Dow Chemical Co.; and Irgasan DP 200, 2,4,4'-trichloro-2-hydroxy diphenyl ether, from Ciba-Geigy A.G.

[0074] The fragrance can be included in an amount of at least about 0.025%, at least about 0.05%, up to about 1%, up to about 0.5%, or up to about 0.1% by weight of the antimicrobial formulation. Advantageously, low levels of 1,2-hexanediol (4.25%) are shown to dissolve 0.05% of the fragrance without the need for any additional solvent to dissolve the fragrance. This allows the antimicrobial formulation to be free of ethanol and other lower monohydric alcohols (commonly used as solvents), and the elimination of such ethanol and other lower monohydric alcohols helps to reduce or eliminate volatile organic compounds.

[0075] In embodiments, the formulation can comprise a majority of water, such as at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, or at least about 90% water. Such water can be present in a free, unbound form.

[0076] In embodiments, the formulation has a relatively low viscosity, such as a viscosity similar to that of water, to facilitate dispensing and formation of small airborne droplets. For example, the formulation can have a viscosity of up to about 1000 cps, up to about 500 cps, or up to about 100 cps, such as from about 1 cps to about 100 cps.

[0077] In some aspects, the antimicrobial formulation can exhibit at least a 2-log reduction or at least a 3-log reduction against airborne target microorganisms. The target microorganisms can be any of Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, phi6, MS2, or any of a variety of other pathogenic or surrogate microorganisms. The antimicrobial formulation can exhibit such a log reduction against airborne target microorganisms within a given exposure time range, such as within 60 minutes, within 30 minutes, within 15 minutes, within 10 minutes, or within 5 minutes.

[0078] III. Exemplary Air Disinfection Delivery In aspects of the present invention, the antimicrobial formulation described above is delivered as a mist to the air to be disinfected. To effectively deliver the antimicrobial formulation, a number of technical parameters are considered, such as temperature, relative humidity, flow rate, particle size, density, vapor pressure, and other potential parameters. For example, in lower-cost delivery methods, smaller particle sizes are typically associated with relatively lower flow rates. Because of this, there is a need to balance particle size and flow rate to achieve the desired efficacy. Advantageously, the systems, methods, and formulations of the present invention do not require expensive delivery equipment to achieve disinfection or sterilization. For example, existing systems typically require the use of expensive thermal fogging devices to be effective. While such devices can of course be used to deliver the formulations of the present invention, this is not necessary, and disinfection or sterilization of a given airspace can be achieved with simple and inexpensive delivery tools, such as by a trigger sprayer, a trigger spray device, etc.

[0079] A variety of devices can be used to deliver antimicrobial agents. For example, some embodiments can use a pump sprayer, a fine mist sprayer, a nebulizer, an evaporator, a cold fogger, a hot fogger, an ultrasonic dispensing device, an electrostatic sprayer, an insertable dispensing device, or a combination thereof. Different devices can provide different particle size ranges of the delivered antimicrobial agent. Some devices, such as aerosol sprayers and pump sprayers, are low-cost and easy to use. Other devices, such as foggers (especially hot foggers), can have better performance (smaller average particle size), however they are generally large, expensive, and may require training or professional use.

[0080] In an embodiment, the total number of moles of lactic acid or other organic acid delivered to the air and optionally delivered 1,2 - hexanediol can be within a desired range. The total number of moles per cubic meter can be at least about 0.05 mmol / m 3 、at least about 0.075 mmol / m 3 、at least about 0.1 mmol / m 3 、at least about 0.2 mmol / m 3 、at least about 0.3 mmol / m 3 、at least about 0.4 mmol / m 3 、at least about 0.5 mmol / m 3 、up to about 5 mmol / m 3 、up to about 4 mmol / m 3 、up to about 3 mmol / m 3 、up to about 2.5 mmol / m 3 、up to about 2 mmol / m 3 or up to about 1 mmol / m 3 。The mass ratio or molar concentration ratio of 1,2 - hexanediol or other diol to lactic acid or other organic acid can be within the ranges mentioned herein (e.g., about 3:1 to about 1:3, greater than 1:1, about 1.2:1 to about 4:1, or about 1.5:1 to about 3.5:1 or about 1.5:1 to about 2.5:1). In an embodiment, lactic acid can be dominant, for example where the ratio of lactic acid to diol is greater than 1, such as from about 1.1 to about 2:1, or from about 1:1 to about 1.5:1, or from about 1:1 to about 1.3:1 (e.g., about 1.1:1). The provided concentration values are calculated theoretically based on the assumption that all chemicals are completely evaporated into a gaseous form. Such values will generally be overestimated relative to empirically measured values.

[0081] Some embodiments may employ a stepwise delivery method (e.g., delivering any diol followed by an organic acid, or vice versa). For example, the first step may include delivering 1,2 - hexanediol or other diols, while the second step may include delivering lactic acid or other organic acids. Advantages of such a stepwise delivery method may include improved efficacy in cases where the target microorganism is an enveloped virus.

[0082] IV. Examples The antimicrobial preparation comprises one or more organic acids and optionally one or more diols. To determine viable organic acids, a number of organic acids were screened. In an embodiment, viable organic acids may have: (1) a vapor pressure of at least 0.02 Pa and less than 1000 Pa, less than 500 Pa, less than 300 Pa, less than 200 Pa, less than 100 Pa, less than 50 Pa, or less than 20 Pa under standard conditions (e.g., 20 °C and 1 atmosphere); (2) be soluble in water (e.g., at least 10 g / 100g water); and / or (3) have an ECHA general population inhalation threshold greater than 10 mg / m 3 (or similar criteria), i.e., be substantially harmless to humans. The results of the screened organic acids are shown in Table 1, where lactic acid was identified as meeting the desired guidelines.

[0083] Table 1

[0084] 1 = Acceptable 2 = Possible 3 = Unacceptable In addition to the organic acids tested, a number of glycols, alcohols, diols, and other candidates were screened for pairing with the organic acids. Viable candidates may also have: 1) the vapor pressure characteristics as mentioned above; 2) be soluble in water; and / or 3) have an ECHA general population inhalation threshold greater than 10 mg / m 3 . Additionally, when actually deployed together, viable candidates should exhibit antimicrobial synergy with lactic acid or other selected organic acids. The results of the candidate screening are shown in Table 2, where 1,2 - hexanediol (HDO) was identified as meeting the desired guidelines and was shown to have synergy with lactic acid. In particular, synergistic results were observed for the combination of 1,2 - hexanediol and lactic acid, especially when the mass ratio or molar concentration ratio of 1,2 - hexanediol to lactic acid could be in the range of 3:1 to 1:3. Further evidence of synergy is shown in Figure 10 .

[0085] Although a variety of diols were screened, the data did not show any significant synergism provided when the diol was present. Thus, although the diol may optionally be present, in embodiments, the formulations of the present invention may be without or substantially without such diol components (particularly propylene glycol and diols including ether groups). The same may be true for the various other candidate materials mentioned in Table 2.

[0086] Table 2

[0087] A promising combination of lactic acid (LA) as an organic acid and 1,2 - hexanediol (HDO) as a diol was identified to be included in the antimicrobial formulation. A variety of experiments were conducted to determine the potency of different factors of the antimicrobial formulation, and the potency will now be discussed in more detail.

[0088] Figure 1 and Figure 2 The figure shows the log reduction of the antimicrobial formulation containing 2% lactic acid and 4.25% HDO relative to the baseline (untreated) control against different target microorganisms. Figure 1 The log reduction against Staphylococcus aureus within a 40 - minute exposure time is shown. The antimicrobial formulation was delivered at different concentrations in a chamber based on the number of presses from a trigger spray device (e.g., available from FLAIROSOL). Figure 1 The figure shows that as the dose increases (by more presses), the log reduction against Staphylococcus aureus is greater. After 40 minutes, the antimicrobial formulation provided approximately 3 log reduction with 15 presses, providing a delivered formulation concentration of 0.682 g / m 3 and a delivered formulation concentration of 1 g / m 3 with 22 presses, achieved 3 log reduction in approximately 10 minutes. Although 2% lactic acid and 4.25% HDO is one example, many other examples are of course possible, and some of these examples may perform even better. For example, another formulation may contain approximately 3% lactic acid and approximately 2.5% HDO. Within an HDO:LA ratio of approximately 3:1 to approximately 1:3, many examples are possible.

[0089] Figure 2 The log reduction against MS2 within a 40 - minute exposure time relative to the baseline (untreated) control is shown. The antimicrobial formulation was delivered at different concentrations based on the number of presses from the same type of trigger sprayer as used in Figure 1 above. Figure 2 It is also shown that at approximately 15 presses (0.682 g / m 3) a certain degree of efficacy plateau or diminishing returns at that time, because after about 20 minutes, it is not much different from 22 pressing instances (1 g / m 3 )

[0090] Figure 3 The figure shows a three-axis graph, where one axis plots the total moles of the delivered lactic acid / HDO antimicrobial agent, another axis plots the mole fraction of HDO in the delivered agent, and the third axis plots the normalized log reduction of the agent delivered per g / m 3 to the treated airspace. In Figure 3 , the target microorganism is phi 6. In this example, the antimicrobial agent is delivered by a trigger sprayer of a similar type as in the previous example, and a 10-minute exposure time is provided. Figure 3 Specifically shown is how the achieved log reduction varies with the total moles (mmol / m 3 ) of the delivered antimicrobial agent and the mole fraction of HDO relative to all HDO+LA in the agent, and there is a synergistic combination. Three levels are shown: low-level concentration (0.254 mmol / m 3 ), medium-level concentration (0.580 mmol / m 3 ), and high-level concentration (1.164 mmol / m 3 ). At the low-level concentration, the efficacy level is driven by the fraction of lactic acid in the antimicrobial agent. At the medium-level concentration, significant efficacy is observed over a wide molar ratio range of HDO to lactic acid (e.g., in the range of 1:3 to 3:1). Since the molecular weights of lactic acid and HDO are similar to each other (90 g / mol vs. 118 g / mol), the molar ratio and mass ratio of the two components are also similar to each other. At the high-level concentration, the efficacy of the antimicrobial agent is improved at shorter exposure times but reaches an efficacy plateau or diminishing returns point at longer exposure times, especially when the agent contains 25% to 75% HDO.

[0091] Figure 4 The figure shows data of the log reduction of phi 6 relative to the percentage of HDO (HDO / HDO+LA) at different molar concentrations of the total active ingredient (HDO+LA). Figure 4 Such data within a 60-minute exposure time are shown. An efficacy plateau or diminishing returns begins around 25% to 75% HDO in the antimicrobial agent, demonstrating that a specific HDO+LA ratio provides synergy.

[0092] Figure 5The figure shows data of the log reduction of phi 6 relative to the molar ratio of lactic acid and 1,2 - hexanediol. The log reduction is normalized relative to an untreated baseline. The concentration of 1,2 - hexanediol is kept constant at 3.5%, while the amount of lactic acid is varied to give the desired molar ratio. Multiple exposure times (5 minutes, 15 minutes, and 30 minutes) are tested and the log reduction is determined. A particularly beneficial ratio of a specific synergy is observed near a 1.1 molar ratio of lactic acid to 1,2 - hexanediol ( Figure 5 the dashed oval in

[0093] Figure 6 ). This molar ratio illustrates the synergy between lactic acid and 1,2 - hexanediol, as well as the unexpected result of a peak in log reduction based on this specific ratio.

[0094] Figure 7 The figure shows various step - wise delivery methods of a two - part formulation including lactic acid and HDO, with the normalized log reduction of phi 6 relative to the exposure time. As tested, step - release #1 includes releasing HDO, followed by releasing lactic acid after 2 minutes. This example shows a 3 - log reduction, making it an effective delivery method. The step - wise release delivery can be accomplished in various ways. In some embodiments, lactic acid and HDO can be kept in two separate delivery chambers or delivery devices, where the user first releases one active ingredient, and then subsequently releases the second active ingredient after a given time period (e.g., within 60 minutes, within 30 minutes, within 10 minutes, within 5 minutes, such as within 1 - 5 minutes or within 2 - 3 minutes). In an embodiment, a programmable delivery device (e.g., an insertable programmable dispensing device) can be programmed to provide step - wise release.

[0095] Figure 8The figure shows the log reduction of a prototype formulation delivered at different particle sizes at exposure times of 10 minutes, 30 minutes, and 60 minutes against Staphylococcus aureus. Prototype #1 formulation (2% lactic acid, 4.25% 1,2 - hexanediol) was delivered using multiple spray devices that produced different particle sizes. A 107 m 3 chamber was used for the experiment, and the chamber was dosed with 0.5 g / m 3 of the formulation. The log reduction was normalized relative to an untreated baseline. The median particle size (Dv50) of each spray was measured using laser diffraction. Laser diffraction measured the droplet size at the center of the spray from 6 inches away. As is readily apparent from Figure 8 the figure, smaller particle sizes provided a greater log reduction.

[0096] Figure 9 The figure shows the antimicrobial efficacy of the prototype #1 formulation (2% lactic acid, 4.25% 1,2 - hexanediol) against both Staphylococcus aureus and Klebsiella pneumoniae on a soft surface (e.g., clothing or other fabric). In the case of a 5 - minute exposure time, the formulation was delivered to a 100% cotton surface. The exemplary antimicrobial formulation exhibited a 5.76 log reduction against Staphylococcus aureus and a 6.68 log reduction against Klebsiella pneumoniae.

[0097] Figure 10 The log reduction of multiple formulations against airborne phi 6 was plotted. The multiple formulations included a formulation containing 2% lactic acid alone, a formulation containing 4.2% 1,2 - hexanediol alone, and a formulation containing both 4.2% 1,2 - hexanediol and 2% lactic acid. The formulation containing both the organic acid and the diol showed synergistic results, showing greatly improved log reduction values at all times between 10 minutes and 60 minutes. For example, while lactic acid or 1,2 - hexanediol alone achieved only about a 1 log reduction, in the best case, the combination of the two achieved about a 4.5 log reduction after 10 minutes, several orders of magnitude better than either component alone. Similar results were shown at contact times of 30 minutes and 60 minutes, where the improvement was substantial compared to using either component alone.

[0098] Figure 11 The log reduction of such organic acids against airborne phi 6 was plotted for multiple vapor pressure tests of multiple organic acids. As Figure 10 the data shown in 3It is carried out in an air chamber, where Dv50 is about 70 µm. For each test, 2 g of the formulation containing 222.2 mmol of organic acid was delivered. For the untreated baseline, the log reduction shown at a 15-minute contact time was plotted. Glycolic acid, lactic acid, and pyruvic acid showed good results (greater than 3 log reduction), even without including diols such as 1,2-hexanediol. As mentioned herein, since the ECHA inhalation threshold limit value of glycolic acid is 2.6 mg / m 3 , glycolic acid may be less preferred compared to lactic acid or pyruvic acid. As Figure 11 shown, various organic acids show at least 3 log reduction in vapor pressure from 0.10 Pa to 300 Pa, from 0.10 Pa to 200 Pa, from 0.40 Pa to 300 Pa, from 0.40 Pa to 200 Pa, from 0.41 Pa to 172 Pa, or from 10 Pa to 172 Pa.

[0099] In an embodiment, the selected organic acid has a water solubility of at least about 10 g, at least about 20 g, at least about 24 g, at least about 24.99 g, such as from about 10 g to about 100 g or about 10 g to about 50 g of organic acid per 100 g of water under standard conditions (room temperature and 1 atm). By way of example, lactic acid meets such requirements, glycolic acid has a solubility of about 30 g / 100g of water, and pyruvic acid has a solubility of about 100 g / 100 g of water.

[0100] Without departing from the spirit and scope of the present invention, those of ordinary skill in the art can make various modifications to the present invention to adapt it to various uses and conditions. Therefore, these changes and modifications are properly, reasonably, and intended to be within the full scope of equivalents of the appended claims.

Claims

1. A system for air disinfection, comprising: a. An antimicrobial preparation, the antimicrobial preparation comprising: (i) One or more organic acids; (ii) Optionally, one or more diols; and (a) wherein the organic acid has a vapor pressure in the range of 0.10 Pa to about 300 Pa at room temperature and standard pressure; And b. A device for generating atomized droplets of the antimicrobial agent, wherein the average particle size is less than about 200 μm, such that the agent provides at least a 3-log reduction of airborne Staphylococcus aureus ( Staphylococcus aureus ) or another airborne target microorganism within 60 minutes or less.

2. The system according to claim 1, wherein the device for generating the atomized droplets of the antimicrobial preparation provides an average particle size of less than about 150 µm.

3. The system according to claim 1, wherein the one or more organic acids include lactic acid.

4. The system according to claim 1, wherein the preparation comprises the one or more diols.

5. The system according to claim 1, wherein the preparation comprises the one or more diols, wherein the one or more diols include 1,2 - hexanediol.

6. The system according to claim 3, wherein the lactic acid is included in the preparation in an amount from about 0.1% to about 10%.

7. The system according to claim 3, wherein the lactic acid is included in the preparation in an amount from about 2% to about 4%.

8. The system according to claim 5, wherein the 1,2 - hexanediol is included in the preparation in an amount from about 0.5% to about 10%.

9. The system according to claim 3, wherein the preparation comprises the one or more diols, wherein the one or more diols include 1,2 - hexanediol, and the concentration ratio of 1,2 - hexanediol to lactic acid in the preparation is from about 3:1 to about 1:

3.

10. The system according to claim 1, wherein the pH of the preparation is from about 2 to about 6.

11. The system according to claim 1, further comprising a buffer.

12. The system according to claim 11, wherein the buffer includes citric acid.

13. The system according to claim 12, wherein the citric acid is included in the preparation in an amount from about 0.1% to about 5%.

14. The system according to claim 1, wherein the system provides at least a 3 - log reduction of airborne viruses within 60 minutes or less.

15. The system according to claim 1, wherein the device includes at least one of the following: a pump - type sprayer, a fine - mist sprayer, an atomizer, an evaporator, a cold - fog machine, a hot - fog machine, an ultrasonic dispensing device, or an electrostatic sprayer.

16. A system for air disinfection, comprising: a. An antimicrobial preparation, the antimicrobial preparation comprising: (i) One or more organic acids; (ii) One or more diols; and wherein the organic acid and the diol have a vapor pressure of at least 0.02 Pa at room temperature and standard pressure; And b. A device for generating atomized droplets of the antimicrobial preparation, wherein the average particle size is less than about 200 μm, such that the preparation provides at least a 3-log reduction in airborne Staphylococcus aureus or another airborne target microorganism within 60 minutes or less.

17. A system for air disinfection, comprising: a. An antimicrobial preparation, the antimicrobial preparation comprising: (i) At least one of lactic acid or citric acid in an amount of 0.1% to 5% by weight; (ii) 1,2 - hexanediol in an amount of 0.5% to 10% by weight; (iii) At least one of a fragrance or a surfactant; wherein the preparation comprises at least 80% water by weight; wherein the pH of the preparation is from about 2 to about 4; and b. A device for generating atomized droplets of the antimicrobial preparation, wherein the average particle size of such droplets is less than about 150 μm; wherein the system provides at least a 3-log reduction in airborne Staphylococcus aureus within 60 minutes or less.

18. The system according to claim 17, wherein the device comprises at least one of the following: a pump sprayer, a mist sprayer, an atomizer, an evaporator, a cold fog machine, a hot fog machine, an ultrasonic dispensing device, or an electrostatic sprayer.

19. The system according to claim 17, wherein the preparation provides at least a 3-log reduction in airborne viruses within 60 minutes or less.

20. The system according to claim 17, wherein the preparation comprises the fragrance.

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