Hay fever has been described as a "post industrial \nrevolution epidemic,"' and successive morbidity \nsurveys from British general practice suggest that its \nprevalence has continued to i…
Hay fever has been described as a "post industrial \nrevolution epidemic,"' and successive morbidity \nsurveys from British general practice suggest that its \nprevalence has continued to increase over the past 30 \nyears.) Other evidence suggests a recent increase in the \nprevalence of asthma2 and childhood eczema.3 This \npaper suggests a possible explanation for these trends \nover time.