UV sunlight and health

Exposure to UV sunlight has positive and negative effects on human health. A small amount of UV exposure throughout the year is critical for producing vitamin D, which is difficult to acquire in our diets. Vitamin D helps the body absorb calcium to support bone growth, and low vitamin D levels are related to several adverse health outcomes, such as rickets (Thacher & Clarke, 2011). Vitamin D may also help the body produce serotonin, a compound that contributes to feelings of happiness and well-being (Spedding, 2014; Lesch et al, 1996).

Conversely, and more importantly for New Zealand, too much exposure to UV sunlight leads to skin damage (including melanoma, a form of skin cancer) and cataracts. It also affects plant growth and decomposition. Australasia has the world’s highest rates of melanoma (Ferlay et al, 2014; Ministry of Health, 2016; Whiteman et al, 2016), the most serious type of skin cancer. The age-standardised rate of melanoma for males in New Zealand increased from 1996 to 2013, but there was no discernible trend in the melanoma rate for females in New Zealand over the same period (see figure 18). This difference is likely due to both behavioural and genetic factors (Dunford et al, 2017; Geller et al, 2006).

Melanoma rates are partly linked to our relatively high UV levels, but other factors also contribute to our high incidence of melanoma. New Zealanders with fair skin are particularly prone to skin damage and our general outdoor lifestyle can also lead to more exposure to the sun. Furthermore, our comparatively cool summer temperatures encourage overexposure.

Figure 18

Note: 2014–2015 data are provisional and subject to change.

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