In News & Views, The Built Environment

In Asia, it’s long been tradition to remove your shoes before entering the home. This custom, which is still practised today, is attributed to traditional homes being raised off the ground – meaning you remove your shoes in the entry before stepping up from ground level into the house.

This is in contrast to the Western world, where it is not unusual to wipe your feet, enter the home and keep your shoes on.

The obvious benefit of removing shoes before entering the home is to avoiding treading dirt and mud into that luxury carpet, but have you ever considered how many bacteria we have on our footwear and the benefit of leaving these at the front door?

A study investigating the microbes living on footwear found that the average shoe had 421,000 colonies of bacteria living on it. Some of these were pathogens such as Klebsiella pneumoniae and E. coli, indicating ‘frequent contact with faecal material’ outdoors. The study also found the contaminating bacteria could be transferred into your home by your keeping your shoes on.

As these harmful pathogens have been found to survive in carpets for many weeks at a time, this could be a potential health hazard – especially if you believe in the ‘five second rule’!

Does the amount of bacteria on our shoes reflect where we have been?

We swabbed some of the team’s shoes to find out if the amount of bacteria on our shoes correlates with where we have been.

For our mini experiment, we took 8 candidates and looked at how each commuted to work, with categories of car, bus or walk. Then, we analysed their shoes: was the tread low, medium or deep?

We also observed the location of where each team member worked: whether it was in the laboratory, office or warehouse or out on the road, or a mixture of these areas.

Finally, we considered the location of their home and whether it was in the city, the suburbs or the countryside.

The results:

  • On average, there were 15% more microbes on the shoes of those that walked and caught the bus to work (27 colonies) in comparison to driving (31 colonies).
  • Shoes with medium or deep tread (93 colonies) had 359% more microbial growth when compared to those with a low tread (20 colonies)
  • The highest growth for working location was the laboratory and office (67 colonies), the lowest being those travelling (13 colonies).
  • The team members that lived in the countryside had 177% more colonies on their shoes (74 colonies) in comparison to those living in the city and the suburbs (27 colonies)
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