The South’s leading supplier of hygiene and cleaning solutions

Want to order online?  Click here to register for an eShop account ***

Click to learn about our sustainability position ***

Want to make sure your cleaning and hygiene standards are sufficient for today’s world?  Click here for more details ***


DB Blog #42 – “Kills 99.99% of bacteria”

Tags :
Posted By :
Comments : Off

What does this really mean?

Understandably, nowadays there is a greater emphasis on how much bacteria a sanitising product can kill which is clearly relayed on its packaging.  Quite often we are presented with anything ranging from 99.9% through to 99.999% in a bid to provide us with the confidence that the product in question is fit for the task – but what do these figures actually mean?

So my understanding is this – the percentage figures are referred to as ‘log kills’.  Scientists use a logarithmic scale, to show  the percentage of bacteria killed.  When disinfecting a surface, the efficacy of a product is measured by its ‘log reduction’ – the number of pathogen cells left remaining following disinfection.  The term ‘log reduction’ shows a 10-fold reduction (or one decimal point), which means that with every step, the number of live bacteria on the sanitised surface is reduced by 90%.  Still scratching your head?  Me too!

For example: 

So, if there was one million bacteria on a surface, how much bacteria would remain if cleaned with a sanitising product with different levels of log reduction promise?

Log Reduction Table 

In other words, if you were using a cleaning product that had 99% kill effectiveness as opposed to 99.99% you would be leaving behind 100 times more bacteria on the table.  This might not sound much but in the current climate, every cell pathogen left behind presents a risk.

It goes without saying therefore that choosing a product with a greater log kill is most definitely more effective.  Quite simply, if used appropriately it will help reduce the risk of an outbreak and cross contamination.

Remember though – the percentage log kill will refer to whatever it has been tested against.  It won’t be a blanket kill rate.  Always check the packaging and the microbiology information for your chosen product.

One more thing:

As mentioned in other posts, COVID-19 is part of the Coronavirus family of viruses (as such Coronavirus is its closest surrogate virus).  Currently no single product is known to specifically kill COVID-19.  If you are looking for a product that’s effective against the Coronavirus family of viruses, you would be looking for one that is accredited to EN14476 (giving reference to the strain) and we would suggest you try and aim for a product with as high a log reduction as possible.  Why not talk to us for more information.

Hope this helps!

Yours, DB