From risky play to dirty play: why young children need ‘dirty’ nature play in their lives

Risky play, which describes exciting forms of free play that involve some uncertainty of outcome and a possibility of physical injury, is increasingly recognised as vital to children’s physical, emotional, and cognitive development. However, an equally important but often overlooked form of engagement is ‘dirty play’: the unstructured, tactile interaction with soil, mud, plants and the microbial life that inhabits them. This article explores the developmental, immunological and ecological value of such interactions, which are frequently dismissed or sanitised due to modern hygiene norms and societal perceptions of ‘dirt’ as dangerous or undesirable. We synthesise evidence from microbiome science, environmental psychology and early childhood education to argue that microbially rich natural environments play a crucial role in shaping healthy immune systems, preventing inflammatory and allergic diseases, and nurturing curiosity, sensory development and nature connectedness. Integrating ‘dirty play’ into early childhood settings supports children's health and could cultivate ecological empathy, encouraging deeper, lifelong relationships with the natural world.