Given the hypothesis that particulate air pollution is associated with systolic blood pressure, the effect of daily concentrations of air pollution on blood pressure was assessed in 2612 elderly subjects in the urban area of Bordeaux, France. Blood pressure was measured by a digital monitor. Particle concentrations (PM10) were obtained from the AIRAQ association that operates a local monitoring network of the air quality. To represent the ambient urban air pollution, stations had to be sufficiently correlated (i.e., correlation >0.70) and to have sufficiently similar mean levels of pollution. Linear regression was used to model the association between concentrations of particles (PM10) and systolic blood pressure. We observed associations between the fifth lag hour and systolic blood pressure for an increase of 10 microg/m3 of PM10 (beta = -1.12, 95% confidence interval: [-1.90; -0.30]). Despite contradictory results, fine particles must be considered nowadays as a major component of atmospheric air pollution in which everything must be put into practice in terms of public health actions in order to protect the general population and particularly the elderly group.