EXPLAINED Series: chemical treatments

Bacteria. There’s the good, there’s the bad, but either way, there’s a lot. Just one square inch of skin might have more than 600,000 bacteria on it, and while most are harmless, some can cause disease and illness. These disease-causing organisms are called pathogens, and can be dangerous or even deadly.

Disinfectants are chemical agents that, when applied, can destroy these bacteria and viruses. Each disinfectant works through the “active ingredient” in its disinfectant formula which ultimately disrupts or damages the targeted pathogen’s cell structure.

Because of the multitude of pathogens out there and the fact they can live on any number of different surfaces, it’s imperative that whatever it is you’re looking to disinfect, be it a commercial site, or home environment, you are aware of:

  1. What disinfectant is most suitable for your situation
  2. In what way it should be applied

There are certainly a lot of disinfectants out in the market to choose from, and this can feel overwhelming, especially as you’re dealing with the health, hygiene and safety of those around you. In this article we’ll take you through some of the more common chemical disinfectants available, explaining what they are made up of, as well as the pros and cons plus circumstances in which they should be used. In addition we’ll go into how best to apply these solutions so that they can be used successfully and safely.

It is our aim that by the time you finish reading this, you will be able to make a more informed choice about which chemical disinfectant is right for you.



Chlorine-based disinfectants are one of the most commonly used disinfectants today. They have helped improve the lives of billions across the globe, and are also used in a number of different circumstances over a diverse range of scenarios such as water-treatment, healthcare, and food prep.

In terms of its specific uses as a disinfectant there are three areas where chlorine is particularly effective:

The first is within water-treatment, with chlorine helping to keep drinking-water safe to consume and swimming pools safe to swim in. This is especially relevant in developing countries as chlorine-based disinfectants treat waterborne diseases such as cholera, dysentery, typhoid and hepatitis A.

Secondly, chlorine is a good option for household disinfectants, since they are great at tackling germs which have settled on kitchen-counter/bathroom surfaces that can make people sick, and are effective in disinfecting clothes (as well as whitening/brightening them). These products will have a lower concentration of chlorine, usually around 5-6%, or 7.5% at the stronger end of the spectrum. If you are intending to use a chlorine-based disinfectant within a household setting, it’s important to make sure that it is less concentrated rather than more, since an especially concentrated formula as that can be too harsh on surfaces, potentially damaging them.

Chlorine-based disinfectants are also commonly used in the food-industry, protecting restauranteurs, customers, and factory workers from bacteria and viruses that they might be more exposed to in a commercial setting. E. Coli and salmonella are just two examples of bacteria that can be found on food-preparation surfaces and that chlorine will deal with effectively.

Whilst these examples demonstrate that chlorine-based disinfectants are extremely good at killing an array of germs, there are some aspects of this chemical that one should be aware of:

  • Amongst all of its bacteria-killing properties, chlorine, when handled improperly, can be a lethal and harmful substance. Always be sure to use chlorine-based disinfectants in a well-ventilated space, since the resulting vapors can be fatal if inhaled. If you do need to disinfect in an enclosed space (i.e. somewhere you will be cleaning low to the ground), be particularly careful, since chlorine-gas is heavier than oxygen and will sink to the floor.
  • Further to this, do not mix any chlorine-based solution with other household cleaners, as this can create substances dangerous to human health. For example, mixing chlorine with any ammonia-based product will create ammonium chloride, severely affecting your throat, eyes and lungs.
  • Finally, always read the manufacturer’s directions and take the proper safety precautions such as using gloves and goggles. Chlorine is an irritant on the skin, so can cause skin problems if applied incorrectly.

Hydrogen Peroxide

Hydrogen peroxide’s use as a disinfectant is more nuanced than that of chlorine, mostly due to its unstable chemical makeup. Hydrogen peroxide is essentially a water molecule plus an extra oxygen atom, and this additional atom breaks apart easily, giving it its unstable properties. This is why H2O2 is such a useful chemical disinfectant, since it is an incredibly reactive molecule that is very good at breaking down biological substances.

Hydrogen-peroxide-based disinfectants are particularly effective when it comes to sterilizing equipment, particularly heat-sensitive materials that can’t be decontaminated in a pressure chamber like an autoclave. It sees a lot of use in hospitals and for disinfecting medical equipment, but can be also used in other commercial indsutries.

In companions to chlorine, it is often seen as the safer alternative because it constituent parts are essentially water and oxygen. Indeed at a 3% concentration, hydrogen peroxide can be used in your mouthwash from the dentist, highlighting how it can have a relatively benign nature.

On the other side it can be slightly less effective than other chemical disinfectants out there if used in the wrong conditions. It directly kills pathogens yes, however, should the intended-surface not be cleaned properly and have other foreign materials on it such as soil or dirt, then H2O2 will break up quickly rather than breaking down its intended pathogen-targets. If hydrogen peroxide is to be used on a particular surface, then a thorough surface-clean must be part of the process to achieve effective disinfection.

Ecological PH Neutral Options

Between chlorine beach and hydrogen peroxide, their place on the pH scale ranges from acidic to alkaline, which dictates their use and effectiveness as a chemical disinfectant. Alkaline solutions are better at dissolving baked-on proteins and fats, so will be formulated into oven cleaners, whilst toilet cleaners will usually be acidic as they are better at dissolving lime scale and rust.

Of course there are drawbacks to these alkaline/acidic pH’s. Yes they are great at breaking down molecules and killing germs, but they can be corrosive to the skin and damaging to surfaces. Not only that, but if indisposed of improperly, can have a negative impact on the surrounding environment such as contaminating groundwater, or affecting marine life.

Fortunately there are more ecologically friendly alternatives these days in the form of pH neutral options that are gentler on surfaces, less dangerous to humans, and less harmful to the environment. The pH scale ranges from one to fourteen, with the mid-point “seven” being neutral, anything less than seven being acidic, and anything over seven being alkaline.  

PH neutral disinfectants such as buckeye E23 and Simplegreen are formulated to be non-toxic, biodegradable and environmentally friendly. Their use can be broader and less specific than those of either acidic or alkaline-based disinfectants, and are used in hospital, healthcare and industrial settings.

An advantage of a neutral pH cleaner is that as it doesn’t have the more corrosive properties of an acid or alkaline-based solution, no rinsing post-application is required, and the solution won’t harm or dull floor finished. These disinfectants therefore tend to be a safe cleaner for most hard surfaces, and its lower risk-factors make it ideal for use in many institutional or commercial settings such as schools, hospitals, and public bathrooms.

There are questions on how effective pH neutral disinfectants can be in comparison to their harsher counterparts but developments in this area are always being made. Indeed many manufacturers are constantly looking to create more eco-friendly disinfectants which minimize any adverse effects on the planet, and are just as effective at eliminating disease, germs and bacteria as chlorine and hydrogen-peroxide.

How to Apply Chemical Disinfectants Properly So That They Can Be Highly Effective

It doesn’t matter what kind of chemical makeup a disinfectant formula has if it’s not applied properly. Applying chemical disinfectants in the right manner is integral to their effectiveness in removing harmful bacteria from your environment. Here are seven key application tips to ensure your disinfectant performs as well as it can do.

  1. Keep Your Solution Clear

When cleaning large surface areas, it’s necessary to have a large bucket of disinfectant solution from which to mop the floors with. However, as the floor is cleaned, the mop itself will pick up dirt and bacteria, which will be transferred back to the bucket of solution as you progress. Eventually there will be enough dirt transferred to not only contaminate your solution and make it less effective, but also end up transferring germs back to the surfaces you are cleaning and even re-spreading it to other rooms. Be sure to switch out your mop-head as often as you can (typical healthcare practices recommend once every two to three medium-sized rooms), and maintain a clear solution replacing it with a fresh batch when possible.

  1. Target the Key Areas

Key areas are the hot spots which provide ideal conditions for bacteria to thrive, and also include surfaces where they are most likely to spread to others (for example lift buttons, handrails and bathroom door handles). If you fail to target the right areas, all your disinfecting efforts could be for none. Don’t forget the less obvious places too such as hand dryers, paper towel dispensers and the handles of kitchen & bathroom taps.

  1. Clear Out Visible Dirt

As much as we’d like them to, chemical disinfectants can’t do all the work. Be sure to clear as much surface dirt as possible so that your disinfectant can get straight to the bacteria it’s designed to destroy. You’ll use less disinfectant, and with far more effective results.

  1. Use the Correct Disinfectant

Different disinfectants have different purposes, and work better with some bacteria over others. Be sure to read the label and directions of your disinfectant before you apply it, taking care to note hazard warnings, first aid directions and the targeted-bacteria.

  1. Get Your Ratios Right

Your guidelines will also mention the concentration and dilution ratios at which your disinfectant will perform optimally. It is important to stick to the exact measurements given since if your solution is too diluted it might not get rid of the bacteria; too concentrated and it might be especially hazardous.

  1. Timing is Everything

Your chemical disinfectant needs time to work its magic, so let the solution settle according to the manufacturer’s instructions as this will vary from product to product. For example, Clorox’s Disinfecting Bleach advises leaving the solution for five minutes before wiping off, whereas Kirkland’s disinfecting wipes say three minutes. This duration is known as “contact time”, describing how long a surface should remain wet with the disinfectant for optimum effectiveness. Rinsing the surface before the recommended time will impair the disinfect’s ability to kill as much bacteria as advertised. It’s also important to note that in certain situations (for example when disinfecting items that come into contact with mouths or food) you could be directed to rinse the item with warm water after the allotted contact time is up, and allow the surface to air-dry. 

  1. Don’t Mix and Match

Perhaps the most important point to note on this list. Firstly, mixing one disinfectant with another substance could render it useless since its germ-killing properties could be made redundant. Secondly however, the resulting product might be incredibly dangerous to both yourself and others. Don’t run the risk.


Throughout this article we’ve drawn attention to the potential risks of chemical disinfectants, however, they can still be used safely around children and pets with proper use. Directions will be clear, so a read of the guidelines will give you suitable instruction. Safety labels for example will state “keep children and pets clear from area until surface has dried”, but nonetheless, it’s important to keep your cleaning products in a place that your children and pets cannot access.

If you are particularly worried about the acidic or alkaline content of your disinfectant, then (as mentioned above) pH neutral and non-toxic disinfectants are available. Indeed even when it comes to artwork and electronics, there are a range of products on the market designed to disinfect without causing any damage, such as Thymol or pre-moistened disinfecting wipes.



With the array of disinfectant products available today, there is a disinfectant out there to meet your needs. Choosing the correct product for your purposes and then understanding the right way to use it will ensure you have a disinfectant that can be used both effectually and safely.

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