Australian Golfers get enough vit D in late afternoon 2009 
Photodermatol Photoimmunol Photomed. 2009 Dec;25(6):317-24.
Measurements of the upper body ultraviolet exposure to golfers: non-melanoma skin cancer risk, and the potential benefits of exposure to sunlight.
Downs NJ, Schouten PW, Parisi AV, Turner J.
Faculty of Sciences, University of Southern Queensland, Toowoomba, Qld., Australia. downsn@usq.edu.au
BACKGROUND: Geographically, Queensland presents an extreme ultraviolet exposure climate to members of the public engaged in outdoor recreational activity. The risk of developing a skin cancer or an eye disease as a result of incidental exposure to naturally occurring ultraviolet radiation in the outdoor environment is proportionately high in a Queensland population compared with fair-skinned population groups residing in comparable Northern Hemisphere latitudes. In contrast to these risks, elderly members of this high growth population group have been reported to be vitamin D deficient. The risks and potential benefits of exposure to sunlight in southern Queensland are assessed in this study with respect to recreational golfing. This sport is a popular recreational activity for the Queensland population and must be played during daylight hours. 
METHODS: The erythemal and vitamin D effective ultraviolet exposure measured to the forearm, upper back and vertex are presented for individuals playing golf under various atmospheric conditions in a 7-month period extending from summer to winter. 
RESULTS: Mean summertime exposures were measured in the 2008 study period as be 1.4, 2.2 and 3.2 standard erythema doses (SED) at forearm, upper back and vertex sites, respectively, compared with respective wintertime forearm, upper back and vertex exposures of 0.2, 0.3 and 0.5 SED, where summertime exposures were recorded in the mean solar zenith angle (SZA) ranges of 56-59 degrees and wintertime exposures were recorded in the mean SZA range 74-83 degrees. Vitamin D(3) effective exposures were determined to vary from between 225, 325 and 475 J/m(2) during summer and 48, 59 and 88 J/m(2) during winter for the respective forearm, upper back and vertex body sites measured in the above mean SZA ranges. 
CONCLUSION: Exposures to ambient ultraviolet during winter on the golf course between 15:00 and 17:30 hours could be beneficial for office workers for the production of vitamin D. Optimizing exposure periods to late afternoon in the winter months and taking adequate sun protection measures in the summer months are important strategies that golfers can utilize for long-term preventative health.

PMID: 19906167 [PubMed - indexed for MEDLINE]