To prevent illness from a biological hazard, we need to prevent workers from being exposed in the first place. This includes proper cleaning and sanitizing. It’s important to make the distinction between the terms cleaning, disinfecting and sanitizing.
The U.S. Centers for Disease Control defines them as follows:
- 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.
- 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.
- 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 takes time
The process of disinfecting is very precise. It is directly related to the four “C’s”, listed below. The four C’s will be precisely described in the usage instructions on all disinfecting products:
- 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.
According to Health Canada, chemical disinfectants that are effective against viruses (like the coronavirus) are also suitable for decontamination of SARS-CoV-2 virus. These include:
- sodium hypochlorite solution (bleach 5.25%) diluted 1:100
- Alcohol-based disinfectant (60-80 percent ethanol or 60-75 percent isopropanol)
- 0.5 per cent hydrogen peroxide, and
- Quaternary ammonium compounds, and phenolic compounds (common in many household cleaners, see ingredients on package)
A full listing of Health Canada-approved hard-surface disinfectants and hand sanitizers for COVID-19 can be found here.
IMPORTANT: Under WHMIS regulations, employers must provide information and training on the hazards, safe handling, use, storage and disposal of any new or existing chemical or hazardous product in the workplace. Refer to supplier label and the safety data sheet for additional information. More information on WHMIS can be found here.
Cleaning Hard (Non-porous) Surfaces (For a list of hard-surface disinfectants for use against coronavirus (COVID-19), see Health Canada’s website):
- If surfaces are dirty, they should be cleaned using a detergent or soap and water prior to disinfection.
- For disinfection, most common EPA-registered household disinfectants should be effective.
- Follow the manufacturer’s instructions for all cleaning and disinfection products for concentration, application method and contact time, etc.
- Additionally, diluted household bleach solutions (at least 1000ppm sodium hypochlorite) can be used if appropriate for the surface. Follow manufacturer’s instructions for application, ensuring a contact time of at least 1 minute, and allowing proper ventilation during and after application. It should be noted that children are a vulnerable population and even small amounts of cleaning products in the air may irritate airways in children with asthma so children should not be present when cleaning is occurring and they should not be allowed onto the bus until all appreciable odors have completely dissipated. Workers assigned to perform the cleaning function should similarly be evaluated for respiratory conditions that may put them at risk when performing this task. Check to ensure the product is not past its expiration date. Never mix household bleach with ammonia or any other cleanser.
Cleaning Soft (Porous) Surfaces:
- For soft (porous) surfaces such as carpeted floor, rugs, and drapes, remove visible contamination if present and clean with appropriate cleaners indicated for use on these surfaces.
- After cleaning , if the items can be laundered, launder items in accordance with the manufacturer’s instructions using the warmest appropriate water setting for the items and then dry items completely.
Cleaning Electronics / Vehicle Equipment:
- For electronics if used, remove visible contamination if present.
- Follow the manufacturer’s instructions for all cleaning and disinfection products.
- Consider the use of wipeable covers for electronics.
- If no manufacturer guidance is available, consider the use of alcohol-based wipes or sprays containing at least at least 60% ethanol or 70% isopropanol to disinfect touch screens.
- Dry surfaces thoroughly to avoid pooling of liquids.