What is dirt made of

On the trail of dirt

What is dust actually made of? What exactly is the difference between cleaning and plastering? And what is the most effective way of getting your four walls clean? We take a very close look and reveal the secret of a sparkling clean apartment.

Pretty dusty

Who does not know that? The house shines freshly cleaned from the attic to the basement, windows and doors remain closed after being ventilated - but a little later, a very fine layer of dust settles on the furniture, houseplants and the floor. Unfortunately, mopping, sweeping or vacuuming often only help temporarily, because wherever people live, dust is inevitably raised. But where does dust actually come from and what is it made of?

The zoom through the electron microscope reveals that dust is a “colorful mixture” of particles of different sizes that mix and connect with one another. From dead skin and carpet fibers to pollen and pet hair to fine dust, everything is included - a "found food" for uninvited guests such as dust lice, house dust mites, bacteria and mold spores. Depending on the particle size and weight, the dust is carried into every corner by the circulating air or wafts around permanently without settling.

The composition of house dust differs depending on the room, the location of the house and the number and way of life of the residents. We carry a large part of the pollution into our rooms with our shoes. That is why gratings, coconut and textile mats or rubber profiles are worthwhile as "dirt trapping zones". Placed in front of the entrances, they catch a large part of the dirt that would otherwise end up in the hallway or other living spaces. Ventilation also causes soot, fungal spores or pollen to get into the house.

Types of dirt

To put it simply, soiling is divided into three types:

  • Coarse dirt, for example scraps of paper, autumn leaves
  • Fine dirt, for example sand, dust, earth
  • Liquid dirt, for example water, oil, solvents

Dirt can also have different contaminating properties:

  • It lies loosely on a surfacesuch as sand or dust
  • It is fixed on a surfacesuch as glue residue, protein, fat
  • It damages the surface mechanically, such as sand, pebbles
  • It consists of microorganismssuch as bacteria, viruses or fungi


Not just cleaning, but maintaining

Anyone who deals with contamination cannot avoid “cleaning up”. Cleaning is defined as "the removal of a foreign substance that is undesirable on a surface". Every cleaning process aims to remove contamination using the most efficient cleaning method possible. In the household, this primarily includes sweeping, vacuuming, brushing, dry and wet mopping.

Just like dirt, cleanliness is also divided into different types:

  • Visually clean - Dirt can no longer be seen on a surface with the naked eye
  • Bacteriologically clean - a surface is free from living microorganisms
  • Physically clean - Even with a magnifying glass or microscope, no more dirt is visible on a surface
  • Chemically clean - a surface is free of oxygen compounds and chemical substances

But why do we put so much time and effort into the thorough cleaning of our living space - in Germany an average of 3.17 hours per week, as an international cleaning study by Kärcher shows? Because not only is a clean home important to us, but also maintaining its value, i.e. looking after our property. In addition, reasons such as aesthetics, safety and image make us resort to vacuum cleaners, steam cleaners, cordless brooms & Co.

Interview with Martin Lutz

In an interview, Martin Lutz, Managing Director of the Research and Testing Institute for Facility Management GmbH, reveals where the biggest sources of pollution are hidden in your own four walls.

Mr. Lutz, how do you define dirt?

I always describe dirt as “matter in the wrong place” and I like to give the following example: jam on bread and butter is matter in the right place, jam on the floor is matter in the wrong place. Whether an environment is perceived as dirty or not always depends on subjective perception, especially in private surroundings. So it is difficult to define dirt in general terms.

Are there typical types of dirt that can be found in every living space?

Loose fine dirt can be found in every apartment, primarily dust, lint and hair.

How do you remove this loose fine dirt most effectively?

First of all, one should be clear about the difference between cleaning and cleaning. When you clean, you are aware of what you are doing and choose the cleaning method based on the degree of pollution. When you clean, you only clean for the eyes. A good example is dusting. Here many instinctively reach for a damp cloth. House dust can be removed much more effectively with a dry microfiber cloth or a feather duster, because the electrostatic properties of the cleaning textiles can be used and dust can thus bind much better. So you should ask yourself the question: "Are you still cleaning or are you already cleaning?"

How has the dirt in our living spaces changed over time?

In the past, dirt often came from within, for example from soot particles from ovens with open flames. Nowadays we carry a lot more outside dirt into our houses and apartments.

The composition of the dirt has of course also changed as a result of environmental influences. There is also a big difference when it comes to the surface materials used. In the past, surfaces were often "broken clean". For example, floors were actually covered with wiping wax, which is often seen with old parquet floors.

Nowadays, the original condition of a surface should be preserved for as long as possible. Maintaining value through targeted cleaning in combination with care has become much more important to people. A lot has also changed with regard to the range of cleaning agents. The market is now littered with products with fantasy names that make it difficult to see what they were actually developed for. It seems that the good old all-purpose cleaner has had its day ...

In which rooms is there the most dirt?

As mentioned before, dirt is a very subjective matter. When it comes to dust, experience shows that the hallway is the dirtiest area because we carry a lot of “dirt” into the house with our shoes. A doormat should therefore not be missing in front of any entrance.

But there is also pollution that is hygienically questionable, i.e. when a surface is contaminated with living microorganisms. In many households, the handle bar on the refrigerator is often more contaminated than the toilet seat. People go shopping, grab things like the handle of the shopping cart and at home immediately put the groceries in the fridge without washing their hands first. All areas that are in frequent skin or hand contact should be cleaned regularly. These include front door and car handles as well as devices with touch displays such as cell phones and tablets.

Which cleaning trends will find their way into our four walls in the future?

Cleaning will always adapt to the surfaces, not the other way around. Our living spaces should not only be clean, but should also be kept in their original state for as long as possible - maintaining value through effective cleaning methods and care products will therefore play an increasingly important role.

It is also becoming more and more important to consumers that as little chemicals as possible are used, either through more environmentally friendly means or through ever better devices with which dirt can be removed in a manner that is gentle on the surface. There is only one thing I can "predict" with certainty: One hundred percent cleanliness and self-cleaning surfaces are initially just dreams.

Cleaning checklist

Cleaning effectively means choosing the right cleaning method in combination with the right cleaning agent - our checklist will help you to be very specific when cleaning your house next time. Before you start cleaning, ask yourself the following questions:

What type of pollution is there?

Is it water-soluble dirt such as road dirt or oil / grease-containing dirt such as food grease?

Which surface is found to be cleaned?

  • What surface material is the object to be cleaned made of and what is it sensitive to?
  • Which accessories (e.g. brush / cloth) are suitable for the surface?
  • How big is the object / surface to be cleaned?
  • Is the surface texture smooth, rough or porous?

Which cleaning method is useful?

Coarse and fine dirt can be collected with a broom. Brooms with soft bristles are suitable for indoor use and sensitive floors, hard bristles are best used outdoors. The dirt must be picked up with a hand brush and dustpan. Since dust is always thrown up when sweeping, it is often useful to wipe it with a damp cloth. Tip: Use a cordless broom to remove dust mice, crumbs, etc., particularly quickly and reliably.

The vacuum cleaner can be used to thoroughly remove dirt such as hair, lint or sand from floors, carpets, carpets and non-slip surfaces.

Hard floor coverings can easily be freed of loosely lying dirt such as lint, dust and hair by slightly damp or dry wiping, also known as dust-binding wiping. Professional cleaning systems, active fiber mop covers or dust-binding cloths that are electrostatically charged are ideal for removing loose dirt from the surface.