Professor Strachan’s research career started in the mid-1980s when he studied the effect of indoor dampness and mould growth on asthma in childhood. In 1989 he published a short paper in the British Medical Journal which speculated that infections might protect against allergic diseases. This article has subsequently received more than 2800 citations and has been dubbed the “hygiene hypothesis”.

During the 1990s, Professor Strachan studied the effects of outdoor air pollution and indoor air quality on respiratory disorders, and the possibility that chronic infections might increase the risk of cardiovascular disease. He continued to research specific aspects of the “hygiene hypothesis” for allergic diseases.

During the 2000s, his research explored lifecourse influences on health in the British 1958 birth cohort, and he led the development of a nationally representative DNA collection, based on this cohort, for use in genetic epidemiology. This led to numerous international collaborations investigating combinations of genetic and environmental influences on disease, particularly respiratory and allergic conditions, and cardiovascular risk factors.