The Wellcome Trust supports diverse research into dirt, including looking at the links between excessive cleanliness and allergies, discovering the most effective ways to encourage hand washing, delving into the psychology of disgust or developing new techniques to tackle ever more virulent microbes.

Find out more about the science of dirt in this section, written by Penny Bailey.

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  Have we gone too far in our war on dirt?

  Our discovery over the last century or so of the microorganisms that cause disease has driven us to develop an arsenal of weapons against them. But have we gone too far?

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  Do we all feel the same way about dirt?

  Does dirt have different meanings for people from different cultures?

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  Is dirt the inevitable price of city life?

  A historical look at the effects of urbanisation.

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  Friend or foe? We need water and air to live, but both can carry - and disperse - dirt

  Water-borne diseases and pollution are the negative sides to water and air.