Ultraviolet exposure patterns of Irish and Danish gardeners during work and leisure

Skin cancer, caused by solar ultraviolet (UV) radiation, is a growing problem in Europe. Reliable data on occupational exposure of outdoor workers are needed to develop protective strategies.

To compare UV radiation exposure patterns between outdoor workers in two European populations.

Fifty-three gardeners, 31 Irish and 22 Danish (age range 24-69 years) wore personal UV dosimeters, measuring time-stamped UV doses continuously during a 4-month summer period. The current and historical sun exposure pattern was recorded by means of a diary and questionnaire. Assessment of pigmentation, naevi, freckles and solar lentigines was performed. The relationship between UV dose and sun exposure pattern was analysed.

Regarding work days, the Irish had a significantly lower percentage of ambient UV exposure than the Danes, 4.5% vs. 8.1%; a lower UV dose per day, 0.97 standard erythema dose (SED) vs. 1.6 SED; a lower UV dose between 12.00 and 15.00 h, 0.43 SED vs. 0.75 SED; and fewer hours with positive dosimeter measurements, 3.2 h vs. 4.8 h (all values are medians, P < 0.01). Regarding days off work, the same patterns emerged for both UV doses and exposure hours. The Irish had significantly fewer days off than the Danes, median 21 days vs. 49 days, and fewer days with risk behaviour (sunbathing/exposing upper body), median 0 days vs. 8 days (P < 0.01).

The lower UV exposure received by the Irish gardeners may have been due to indoor breaks during peak ambient UV. Other contributing factors may include differences in natural shade between the parks. Our data suggest that consideration of such factors in scheduling of outdoor work can significantly reduce the occupational UV exposure.