Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty. Common types of dirt include: * Debris: scattered pieces of waste or remains * Dust: a general powder of

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

or mineral matter * Filth: foul matter such as excrement * Grime: a black, ingrained dust such as soot *

Soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...

: the mix of

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay pa ...

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class ...

, and humus which lies on top of bedrock. The term 'soil' may be used to refer to unwanted substances or dirt that are deposited onto surfaces such as clothing.

Exhibitions and studies

A season of artworks and exhibits on the theme of dirt was sponsored by the Wellcome Trust in 2011. The centrepiece was an exhibition at the Wellcome Collection showing pictures and histories of notable dirt such as the great dust heaps at Euston and King's Cross in the 19th century and the

Fresh Kills Fresh Kills (from the Middle Dutch word '' kille'', meaning "riverbed" or "water channel") is a stream and freshwater estuary in the western portion of the New York City borough of Staten Island. It is the site of the Fresh Kills Landfill, fo ...

landfill which was once the world's largest landfill.

Cleaning

When things are dirty, they are usually cleaned with solutions like hard surface cleaner and other chemical solutions; much domestic activity is for this purpose—washing, sweeping, and so forth. In a commercial setting, a dirty appearance gives a bad impression. An example of such a place is a restaurant. The dirt in such cases may be classified as temporary, permanent, and deliberate. Temporary dirt is streaks and detritus that may be removed by ordinary daily cleaning. Permanent dirt is ingrained stains or physical damage to an object, which requires major renovation to remove. Deliberate dirt is that which results from design decisions such as decor in dirty orange or grunge styling.

Disposal

As cities developed, arrangements were made for the disposal of trash through the use of waste management services. In the United Kingdom, the Public Health Act 1875 required households to place their refuse into a container that could be moved so that it could be carted away. This was the first legal creation of the dustbin.

Health

Modern society is now thought to be more hygienic. Lack of contact with

microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in old ...

s in dirt when growing up is hypothesised to be the cause of the epidemic of allergies such as

asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...

. The human

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

requires activation and exercise in order to function properly and exposure to dirt may achieve this. For example, the presence of staphylococcus bacteria on the surface of the skin regulates the inflammation which results from injury. Even when no visible dirt is present, contamination by microorganisms, especially

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a g ...

s, can still cause an object or location to be considered dirty. For example, computer keyboards are especially dirty as they contain on average 70 times more microbes than a lavatory seat. People and animals may eat dirt. This is thought to be caused by mineral deficiency and so the condition is commonly seen in pregnant women.

Neurosis

People may become obsessed by dirt and engage in fantasies and

compulsive behaviour Compulsive behavior is defined as performing an action persistently and repetitively. Compulsive behaviors could be an attempt to make obsessions go away. The act is usually a small, restricted and repetitive behavior, yet not disturbing in a pa ...

about it, such as making and consuming mud pies and pastries. The source of such thinking may be genetic, as the emotion of disgust is common and the location for this activity in the brain has been proposed.

References

External links

*
Dirt season at the Wellcome Collection
{{Authority control Hygiene Waste