Asthma is the commonest chronic disease affecting both children and adults, and it is getting commoner. About 7 per cent of the populations of the Western world have been diagnosed by doctors as suffering from asthma. It is not a trivial condition and its dangers must never be underestimated. In Britain alone, more than 5 million people have asthma and 1,500 people die from it every year. Many of these deaths could be prevented, and experts are concerned at the lack of knowledge of the subject among suffers and their families. Failure to understand the principles of treatment and to recognize the danger signs can lead to under-treatment and dangerous delay in seeking medical help when this is urgently needed.