The chest disease asthma is becoming more common. It can lead to life-threatening breathing difficulties when the airways constrict and the lung tissue overproduces mucus; this is usually an allergic reaction that can be worsened by air pollution. But our understanding of what's going on in an asthmatic lung is still quite limited. But now for the first time, scientists at the Sanger Institute near Cambridge have used a new technique to document and examine every cell in lung samples from both healthy and asthmatic patients, to discover what's changing when a person develops asthma. Chris... Like this podcast? Please help us by supporting the Naked Scientists