Associations of Blood Pressure With Geographical Latitude, Solar Radiation, and Ambient Temperature: Results From the Chilean Health Survey, 2009–2010: Table 1.

Mean blood pressure and the prevalence of hypertension vary widely throughout the world (1). Geographical latitude has been cited as a possible explanation for this variance (2– 5), with increasing distance from the equator being associated with higher blood pressures. However, these statements are often not referenced (3) or refer to data from a post-hoc analysis of the International Study of Sodium, Potassium, and Blood Pressure (INTERSALT) (2, 4), which was published as a hypothesis paper in which the authors did not adequately report the methodology so as to allow others to assess the validity of the results (6). In other studies in which similar findings were reported, the differences observed were either explained by factors such as salt intake (7) or were confounded by other significant differences in characteristics such as renal function, diabetes prevalence, lifestyle, and diet (8–12). Ambient temperature and number of daylight hours have also been reported to affect blood pressure and the prevalence of hypertension (13–15)