How to Disinfect Workplaces and Kill Coronavirus
According to a study in the peer reviewed medical journal The Lancet it was discovered that COVID-19 could sometimes last up to 7 days on hard surfaces such as plastic and stainless steel.
Many workplaces throughout Australia, and in particular those that have visitors or are open to the public should improve their cleaning regimes for the health and safety of everyone.
Good practice advice from Safe Work Australia is that daily cleaning with detergent and water is sufficient. This will kill most but not all germs on surfaces.
Ideally, once clean, surfaces should also be disinfected regularly. Where there is a confirmed or suspected case of COVID-19, all surfaces should be disinfected. A specialist clean may be conducted.
With all the extra cleaning activity throughout workplaces, it is recommended that cleaning practices are:
Safe and sustainable for the cleaners in terms of minimising exposure to cleaning agents through the use of safer agents which are less harmful and use of Personal Protective Equipment (PPE) if needed.
Safer for other persons in the workplace if they are exposed to those agents on wet sanitised surfaces.
Frequency and Strength
The diluted strength of various cleaning agents used, together with their frequency of application will depend on a risk assessment that factors in:
How much traffic/human contact the surface is being exposed to. The workplace should be cleaned daily and between shifts. If equipment is shared between workers, it should be cleaned between uses, where practicable.
Whether the environment is harbouring current known positive CV patients or people (symptomatic or asymptomatic). Where there is a confirmed or suspected case of COVID-19, all surfaces should be disinfected.
The vulnerability of the inhabitants or workers in that environment, for example if the people that occupy the spaces are older or are at a higher risk of contracting the disease due to existing medical conditions.
The prevalence of the virus in the general community at that time, which will fluctuate and likely see-saw over the coming months and years.
As a general rule you should always carefully follow the instructions on the label, and wear PPE gear such as gloves and respirator during preparation (dilution) and application of chemicals (especially harsh chemicals such as bleach).
While P2/P95 masks are in very low supply at the moment, lower grade cleaning masks are more readily available. Note that surgical masks will not provide any protection against chemical fumes or vapours. If possible, use a cleaning agent that does not require a respirator.
Pre-Cleaning
The correct method for disinfecting surfaces properly is to first ensure any residual dirt, dust and other foreign material is cleaned off first. This will remove much of the viral load by itself, especially if the cleaning product is also known to deactivate the virus.
Special attention should be given to frequently touched surfaces (e.g. tabletops, door handles, light switches, desks, toilets, taps, TV remotes, kitchen surfaces and cupboard handles).
We recommend using commonly available multi-purpose type cleaners containing either Lactic Acid or Citric Acid for the purposes of pre-cleaning surfaces.
Citric Acid as a Cleaner
One such multi-purpose cleaner that is still often available in most supermarkets is Coles Multi Purpose Cleaner containing Citric Acid 3.2% w/w.
This product contains identical chemicals to Pine O Clean Disinfectant Spray, which is also available at Coles and Woolworths. There are a myriad of similar products available throughout Australia, all containing Citric Acid in approximately the same concentrations as a ‘ready to use’ formula.
Lactic Acid as a Cleaner
Another widely available and inexpensive, safer disinfectant is Lactic Acid. Lactic Acid can also be found in many common household cleaning products, especially bathroom cleaners.
Lactic Acid and Citric Acid one of five common ‘Culinary acids’ or in other words, they are all used in cooking including Tartaric Acid, Malic Acid and Ascorbic Acid. Suffice to say, this means they are much safer and easier to handle than other chemical agents.
Disinfecting
If using disinfectant, follow TGA recommendations. Disinfectants containing ≥ 70% alcohol, quaternary ammonium compounds (such as benzalkonium chloride) or diluted household bleach (including products containing sodium hypochlorite) are suitable for use.
Benzalkonium Chloride as a Disinfectant
This chemical is commonly found in products labelled as ‘Disinfectant’. It is available in large purple lavender fragranced bottles from Coles for just $1.40, and can then be further diluted according to the label.
Benzalkonium Chloride as a quaternary ammonium compound is not a natural disinfectant, and it has been linked to various ailments including skin irritation and dermatitis. PPE such as gloves and masks should be worn if this product is being applied readily (for example disinfecting large surface areas).
One advantage of Benzalkonium Chloride is that it is a quaternary ammonium compound and not acidic. It has less potential to damage or break down soft furnishings or other surfaces. For this reason, it is actually commonly used in household laundry sanitisers.
Bleach as a Disinfectant
Bleach is largely regarded these days as taking a sledgehammer to crack a nut (or in other words, complete overkill). While bleach is an extremely powerful, quick-acting disinfectant, it is also damaging to most floor surfaces, and especially brutal to human skin.
That soapy feeling that imparts on your skin when bleach comes into contact is actually a saponification process (soap making process) as the caustic acid melts the outer barrier of natural oils on your skin.
When there are plenty of other viable disinfectants available, we do not recommend the use of chemical bleach in the workplace other than in special circumstances.
Bleach is also responsible for thousands of emergency department and ambulance call outs every year, due to accidental poisoning and exposure to vapours.
Alcohol as a Disinfectant
Spraying alcohol (solvent) based agents such as rubbing alcohol or isopropyl alcohol 60% or greater, is one of the fastest and effective ways to eliminate CV on hard surfaces.
As a solvent however, alcohol should not be used on painted or varnished surfaces such as walls or treated woods. It can generally be used however on granite benchtops at a concentration of 70%, but consult your manufacturer guidelines, and always test on a small area first.
Diluted alcohol (aka rubbing alcohol 70%) is also ideal for cleaning and disinfecting all glass surfaces and especially metal or stainless steel surfaces.
Alcohol is considered safe for human skin contact, including Isopropyl alcohol notwithstanding the tendency to dry out skin if overused at higher concentrations.
The problem of course, is that obtaining any alcohol based cleaners at the moment including pure isopropyl alcohol is almost impossible. One popular online retailer of solvents in Australia Sydney Solvents was selling a 5L container of 100% Isopropyl Alcohol for $27 including shipping in early March. As at mid April 2020, the same product is advertised at $53.50 but is very much out of stock. They are receiving so many enquiries and demand they are simply ignoring them!
A notice on their website on April 16th reads:
“At this stage, we will not have stock of the Isopropyl Alcohol (IPA) until late April. We are producing some Antibacterial Hand Sanitiser, however, most are committed to orders. If we have any extras, we will place them on the website where you will be able to purchase them. All availability of each product will be outlined on the website, no need to call the office.”
Summary
Avoid chemical bleaches and other harsh chemicals, instead consider using safer agents that contain lactic acid, citric acid or hydrogen peroxide. With all these agents (including Benzalkonium Chloride) to properly sanitise a surface requires it to be cleaned beforehand, and to then allow a saturation of the cleaning solution to penetrate the surface for a period of time (10 minutes or longer).
Before mixing any chemicals, read the article ‘The Dangers of Mixing Cleaning Chemicals’