The spectrum of environmental health hazards has changed over recent centuries, most markedly in the Western world. In the eighteenth century the dominant, familiar hazards were malnutrition, occasional famine and infectious diseases. Later that century, food shortages receded as agriculture began to modernise. The urban crowding and squalor due to early industrialisation in the nineteenth century ensured the continued dominance of infectious diseases. Subsequently, however, in the twentieth century, the spectrum of environmental hazards changed; the expansion of industry, the synthesis of organic chemicals, the intensification of agriculture and the advent of motorised transport increased the levels of local pollution in air, water, soil and food. Meanwhile in low- and middle-income countries recent economic development has supplemented the persistent environmental problems of diarrhoeal disease, malnutrition, and vector-borne infections with the newer health hazards of industrialsation.