The first recognition of the profession of occupational hygienist was preceded by at least 200 years of developments in disease prevention practices in the workplace, many of which could readily be characterized as occupational hygiene. The nature and pace of adoption of these practices depended on the contemporary state of technology, science, medicine and social concern. At first it was a matter of individual initiative and did not depend on quantitative data, but by the second half of the 19th century techniques of measurement for both harmful effects and for exposure were being introduced and official bodies at both national and local level were active. People from a wide range of backgrounds made contributions to disease prevention at work and by 1920 most of the major concepts and practices of current occupational hygiene practice were in place, if only in rather limited settings.