Dirt is unclean matter, especially when in contact with a person's clothes, skin or possessions when they are said to become dirty. Common types of dirt include:

• dust — a general powder of organic or mineral matter
• filth — foul matter such as excrement
• grime — a black, ingrained dust such as soot or ash
• soil — the mix of clay, sand and humus which lies over the bedrock

Cleaning

When things are dirty they are usually cleaned with solutions like hard surface cleaner and other chemicals; much domestic activity is for this purpose — washing, sweeping and so forth.^[1]

In a commercial setting, a dirty appearance will give a bad impression of a place such as a restaurant. The dirt in such cases may be classified as temporary, permanent, or deliberate. Temporary dirt is streaks and detritus that may be removed by ordinary daily cleaning. Permanent dirt is ingrained stains or physical damage which require major renovation to remove. Deliberate dirt is that which results from design decisions such as decor in dirty yellow or grunge styling.^[2]

Disposal

As cities developed, arrangements were made for the disposal of dirt. In Britain, the Public Health Act 1875 required households to place their refuse into a container which could be moved so that its contents could be carted away. This was the first legal creation of the dustbin.^[3]

Health

Modern society is now thought to be excessively clean. Lack of contact with microorganisms in dirt when growing up is hypothesised to be the cause of the epidemic of allergies such as asthma.^[4] The human immune system requires activation and exercise in order to function properly and exposure to dirt may achieve this.^[5] For example, the presence of staphylococcus bacteria on the surface of the skin regulates the inflammation which results from injury.^[6]

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 about it, such as making and eating mud pies.^[7] The source of such thinking may be genetic, as the emotion of disgust is common and a location for it in the brain has been proposed.^[8]

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 landfill which was once the world's largest.^[9]

References

Further reading

• Terence McLaughlin (1971), Dirt: a social history as seen through the uses and abuses of dirt, Stein and Day, ISBN 978-0-8128-1412-5 
• Pamela Janet Wood (2005), Dirt: filth and decay in a new world arcadia, Auckland University Press, ISBN 978-1-86940-348-5 
• Ben Campkin, Rosie Cox (2007), Dirt: new geographies of cleanliness and contamination, I.B. Tauris, ISBN 978-1-84511-672-9 
• Virginia Smith et al. (2011), Dirt: The Filthy Reality of Everyday Life, Profile Books Limited, ISBN 978-1-84668-479-1 

External links

• Dirt season at the Wellcome Collection
• Dirt, a 2008 documentary film about dirt and impurity, National Film Board of Canada
• Dirt! The Movie, a 2009 documentary film that explores the relationship between humans and soil.