VISIBLE AND ULTRAVIOLET-B OCULAR-AMBIENT EXPOSURE RATIOS FOR A GENERAL-POPULATION

Purpose. To estimate the numerical value of the ocular-ambient exposur e ratio (OAER) (ratio of the facial exposure to that on a horizontal p lane) as a function of wavelength band, season, and job category and t o establish the effect of various modifiers, such as geography and the use of hats, for use in general population studies. Methods. Two hund red sixty-four persons within several job categories representing the jobs in our Salisbury, Maryland, population were instrumented with ult raviolet-B (UVB) and visible band sensors for 1 complete day. Studies were done over all four seasons, both xith and without hats. Results. OAERs in the UVB wavelength band generally are higher than in the visi ble (13% versus 6%), display no significant variation with job categor y, show a seasonal effect (highest in the winter-spring [18%], lowest in the summer [10%], and intermediate in the fall [14%]), and are redu ced 34% by the use of hats. In the visible wavelength band, OAERs are affected weakly by job function, although this variation is not signif icant, display a seasonal effect with three seasons as in the UVB, and are not affected significantly by the use of hats. In neither the UVB nor the visible portions of the spectrum did the authors find an effe ct on the OAER due to photophobia or eye color. Conclusions. With the authors' exposure model, the authors have at their disposal a valuable tool for exploring the relation between UVB, UVA, and visible radiati on and a number of age-related eye diseases.