A Usual Occupation Observation is a clinical statement about the type of work (paid or unpaid) done by a person for the longest amount of time during his or her life, not including voluntary work. It includes a set of self-reported, related components about the work a person performed for the longest amount of time during his or her life, regardless of the person's current job and regardless of whether or not the person performed this work for a continuous time. It also can be used in a minor's record for the Usual Work of people who share a home with the person (see optional related subject). Usual Work supports recognition of new and known chronic conditions which evolve over many years and may become evident after the person is no longer performing that type of work, e.g., some respiratory conditions and cancers. These data also are used by public health entities and medical researchers to investigate the relationship between conditions and exposures at work and illnesses, causes of death, or cancer.