Disinfecting Dwell Times

What is a Disinfectant Dwell Time and Why Does it Matter?

Disinfectants require a specific length of time on the hard surface to kill germs. This is referred to as the “Dwell Time” of a disinfectant. This is also referred to as “kill time” or “contact time”. Health Canada words it this way: “allow enough contact time for disinfectant to kill germs based on the product being used”. Dwell times range anywhere from 30 seconds to 10 minutes. And this is important to follow if you wish to get the maximum benefit of your disinfecting process. A simple spray from a hand spray bottle followed by an immediate wipe is not sufficient to kill bacteria or viruses.

How do you know what the dwell time is for the chemical you are using?
Please carefully read the manufacturers directions for use which you will find on the label of the product you are using. The directions will tell you what the dwell times are for sanitizing and for disinfecting. In many cases, the label will tell you to apply your disinfectant to a surface that has already been cleaned. Some products will both clean and disinfect but the key is to clean the surface of grime and coatings that can prevent the disinfectant from getting directly onto the surface.

Cleaning vs Sanitizing vs Disinfecting
Merriam-Webster defines the differences as follows:
Cleaning is done with water, a cleaning product, and scrubbing. Cleaning does not kill bacteria, viruses, or fungi, which are generally referred to as “germs.” Cleaning products are used to remove germs, dirt, and other organic material by washing them down the drain. Sanitizing and disinfecting products are chemicals that work by killing germs. These chemicals are also called antimicrobial pesticides...Disinfectants kill more germs than sanitizers. In most cases, a cleaning product is used first. Then the surface is either sanitized or disinfected when it is necessary.

The U.S. Centers for Disease Control defines these terms below:
Cleaning removes germs, dirt and impurities from surfaces or objects. Cleaning works by using soap (or detergent) and water to physically remove germs from surfaces. This process does not necessarily kill germs, but by removing them, it lowers their numbers and decreases the risk of spreading infection. Coronaviruses, specifically, are encased by a layer that is highly susceptible to the properties of soap. This means that washing hands/surfaces properly with soap is actually ideal.
Sanitizing lowers the number of germs on surfaces or objects to a safe level, as judged by public health standards or requirements. This process works by either cleaning or disinfecting surfaces or objects to lower the risk of spreading infection.
Disinfecting kills germs (bacteria, virus and mold) on surfaces or objects. Disinfecting works by using chemicals to kill germs on surfaces or objects. This process does not necessarily clean dirty surfaces or remove germs, but by killing germs on a surface after cleaning, it can further lower the risk of spreading infection. Objects usually must be cleaned for proper disinfection to take place.

Sanitizers are used on food contact surfaces at low concentrations for a one minute contact time, while disinfectants are used at higher concentrations on non-food surfaces for a ten minute contact time. Sanitizers only claim to kill those bacteria that cause foodborne illness, while disinfectants will claim to kill a collection of bacteria, fungi and viruses. Sanitizers are found in food service, while disinfectants are found in hotels, motels, nursing homes

To disinfect properly requires carefully following the instructions on your product which will in one way or another refer to or imply the "Four Cs”:
Chemistry: The type of chemical that is being used for destroying or inactivating the germ.
Concentration: The level at which that chemical is diluted in solution of water.
Contact time: The amount of time it takes for the disinfectant to sit on a surface before a certain pathogen is inactivated. For example, bleach can take 30 seconds to render a surface free of active E. coli or three minutes for C. difficile spores.
Coverage: The amount of surface area that the disinfectant covers after it’s applied. Ideally this is 100 per cent.

Proper dilution is another particularly important aspect to focus on while using your chemical. Some products are shipped at full strength and require no dilution while others require dilution. It is not good enough to estimate, “eyeball” or “wing” your dilution rates; you must be precise. Dilution rates will be different for Sanitizing vs Disinfecting; disinfecting will require a higher concentration and longer dwell time. You will find dilution rates such as 1:184 or 1:256. You can use measuring tools like measuring cups or syphon measuring tools. If you have concerns about staff following the precise measurements, you can also use Dilution Control Systems. Please contact TheSanitizerStore.ca if you would like to use a dilution control system as we can get these for you at affordable prices.

As an example, for a dilution of 1:256 – you will need 256 parts water for every one-part chemical. So, then based on this dilution rate, for one litre of water you would add 4 mils of chemical and for 20 litres of water you would add 78 mils of chemical. For safety reasons, always add chemical to water, never add water to chemical. This will prevent splashing of the chemical if you were to add water to the chemical.

What is the Most Effective Process to Achieve Ideal Chemical Dwell Times?
Use a disinfectant sprayer. The sprayers we sell on here at TheSanitizerStore.ca provide you the best method of applying your disinfectant. Here is why:

  • Stable stream of spray flows out of the sprayers – more efficient in spraying and more accurate and consistent than hand or pump sprayers
  • Both sprayer manufacturers we carry have three different nozzle or tip sizes to give you the ability to spray to the density you require for your chemical achieve the appropriate dwell time.
  • The Graco SaniSprayers have a variable speed control giving you complete control over the volume of chemical you are spraying.
  • The PAX Electrostatic Sprayers are well suited for offices or spaces where lighter volumes are preferred while the Graco SaniSprayers are perfect for hard surfaces in any environment giving you the ability to achieve proper dwell time consistently every time.
  • The sprayers are effortless to use thus avoiding the fatigue your staff experience using manual methods, and therefore contributing to the accuracy of your spray to achieve the correct dwell times for your chemical

Work with TheSanitizerStore,ca and we will help you choose which device, nozzle or tip, and chemical you need to achieve your disinfecting goals. Dwell times will vary depending on the target surface and the humidity in your establishments.  We have done and can do tests for you on the sprayers to be sure you are purchasing the correct unit for your business.

Here is a Link to Health Canada Cleaning and Disinfecting Guidelines:

Please Click Here to See and Download Health Canada's "Cleaning & Disinfecting Public Spaces"

Please Click Here to See and Download "Creating a Healthy Environment"
This is created for you by our supplier, Avmor

Please Click Here for a link to the Government of Alberta’s Relaunch Guidance Documents

TheSanitizerStore.ca has diligently gathered this information for your use and to the best of our knowledge is correct. The data and information for this though is constantly shifting, especially in the case of Covid-19. This information should not override the information, protocols or regulations of the federal, provincial or municipal agencies or governments.  Please always refer to your local Public Health Authorities.

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