Developing measures of material or psychosocial labour conditions, however, is a somewhat different matter. Also, in contrast to the research on class inequalities in health, the major focus of research on gender differences in ill health has been the aetiological significance of the psychosocial conditions of domestic labour. In contrast, however, women experience a great deal more non-life threatening illness than men and research on gender inequalities in health has focused primarily on this morbidity differential. Research on gender inequalities in health has also paid some attention to mortality patterns. Hours of work, either formal or domestic, may have a different relationship to measures of health which include limitation of activity, than to measures such as symptom checklists. For instance, the experience of pollution, damp, noise, overcrowded and unsafe conditions, are readily seen to be equally applicable to both the domestic and the formal labour sectors.