What is air? You don't think about air or even perceive it unless it has changed from its usual state. Air, that most ubiquitous of the four elements, was long the most inexplicable enigma, peopled by gods and their messengers, venerated as the abode of spirits or demons. Nowadays air has been 'deconsecrated' and almost entirely demystified by science. Its availability is crucial; it envelops us and our planet allows us to breathe and is anything but something to be taken for granted. The book addresses the question of what air is and approaches answering it from two angles. First, through a scientific explanation of its chemical and physical elements, their properties and the effect they have on our immediate environment. In parallel, air is traced as a phenomenon dealt with in art, architecture and design, all of which perceive, represent and creatively use air as a medium in entirely different ways. The focus is on the twentieth century to the present day. The juxtaposition of art, architecture, design and science generates an exciting dialogue on air. An imaginative experiment intended to stimulate all those who are seriously concerned about air as an element vital to our survival.