➡️Contact Time

Contact time is critical! Disinfectant products and methods need time to have their effect. This will vary depending on the product or method selected. For example, 70% isopropyl alcohol can destroy Mycobacterium tuberculosis in 5 minutes, whereas 3% phenol requires 2-3 hours.

Poor application or evaporation during high temperatures will impact sufficient contact times. Surfaces must remain wet (for chemical disinfectants) or exposed (for physical methods) for the full contact time. Some chemicals may have residual activity (i.e., QAC) while others may evaporate quickly (i.e., alcohols), especially with high temperatures.

➡️Disinfectant Concentration

Use of the proper concentration of a disinfectant is important to achieve the best results for each situation. Some products will have different dilutions depending on the desired use of the product (i.e., -static versus –cidal action; sanitizing vs. disinfection action).

While using higher concentrations can be more efficacious, routine use may be limited by the degree of risk to personnel, surfaces or equipment, and cost of the chemical.

However, over-dilution of a product will cause the disinfectant to be ineffective against the targeted microorganism(s). The product label will list the best concentration to use for each situation.

➡️Expense. Economic considerations are always important when selecting a disinfectant. Disinfection is generally a cost-effective means of reducing pathogenic organisms. Disinfectants vary in cost, contact time and dilution. Costs should always be calculated as per gallon of use/dilution (per liter of use /dilution) rather than the cost of concentration.

➡️Human Factor – Ease of use another important consideration is ease of use. How easy or hard is the product to apply? Does the product have an offensive odor? Is a long surface contact time, and possible reapplication required?

➡️ENVIRONMENTAL CONSIDERATIONS

Environmental conditions can have a profound effect on disinfection success.

This includes factors such as the organic load, the type of surface, temperature, water hardness, pH or the presence of other chemicals.

The presence of organic matter (e.g., soil, manure, body fluids, bedding) is one of the most important environmental factors to influence disinfection activity! Organic matter provides a physical barrier that protects microorganisms from contact with the disinfectant. Additionally, debris and organic material can neutralize many disinfectants (e.g., chlorine, QACs), reducing the level of active ingredient available to attack microorganisms.

Ultraviolet light applications, including direct sunlight, have limited penetration below the surface of organic matter. Some disinfectants, such as phenols or glutaraldehyde, are less affected by organic matter, and may need to be considered when the complete removal of organic debris is difficult.

➡️Surface Type

 Surfaces in animal settings can be quite diverse. They may include various metals, glass, rubber, plastic, concrete, wood, or fabric or woven material (e.g., clothes, nets, and ropes). The type of material or complexity of an item can factor into disinfection efficacy.

Surfaces that are porous, cracked, or pitted (e.g., wood, concrete) or that have complex structure, such as hinges, bends, or crevices can be challenging to disinfect effectively.

Some chemical disinfectants can be incompatible with or corrosive to certain materials or surface types. Some products have been developed for use on porous surfaces, but generally require much longer contact times or higher concentrations.

Alternative or supplemental disinfection methods, such as gaseous or vaporous sterilant products or physical disinfection methods (e.g., drying, ultraviolet light) should be used for treating porous surfaces.

➡️Temperature

Temperature is another important environmental factor that can affect disinfectant efficacy. Considerations should include both the ambient temperature as well as that of the disinfectant solution. The exposure temperature is particularly important if you are disinfecting outdoors (e.g., vehicles). Most chemical disinfectants work best at temperatures above 68o F (20 oC).

Lower temperatures can reduce disinfectant efficacy or solutions may freeze in these conditions.

Conversely, while elevated temperatures can aid in microorganism destruction, it can also accelerate the decomposition or evaporation of a disinfectant.

➡️pH

A pH extreme can be detrimental to microorganisms; however environments that are very acidic or very alkaline can alter the effectiveness of some disinfectants. pH changes in the environment may be caused by organic material, water composition (e.g., water hardness ions), or from other chemical products used. These conditions may change the degree of ionization or dissociation of the active ingredient of a chemical disinfectant or the stability of a solution. Examples include phenolics, hypochlorite, and iodine compounds.