Comparison of two personal ultraviolet index monitors for sun awareness in South Africa

Exposure to solar ultraviolet (UV) radiation is known to have both adverse and beneficial consequences for human health. Sunburn and skin cancer are probably the most well-known acute and chronic adverse health impacts. These themes have recently been discussed in the media for the general public; consequently interest in sun protection is growing. The promotion of the use of practical personal strategies to reduce adverse health risks, such as healthy sun behaviour, sun protection mechanisms and solar ultraviolet radiation awareness tools, is increasing. One such tool is the personal UV index (UVI) monitor, promoted commercially as a viable tool for sun awareness; however, such instruments have not been scientifically evaluated in a South African context. Here, two different types of personal UVI monitors, commercially available in South Africa, were compared with a research-grade UVB biometer for a continuous 7-h period on 02 March 2012 in Pretoria. One of the two personal UVI monitors showed reasonable agreement with the UVB biometer, whereas the other monitor overestimated UVI by up to 4 UVI units. When comparing two identical products manufactured by the same company, one monitor overestimated UVI twofold, suggesting inter-instrument variability may be a concern. Commercially available, personal UVI monitors should be used with caution as a public health tool for sun awareness in South Africa.