UV Transmission of Summer Clothing in Switzerland and Germany

Clothing is regarded as an efficient tool for sun protection. Recently, we have learnt that the transmission of UV radiation (UVR) differs substantially between clothing materials. The protection afforded by a light-coloured cotton shirt is equivalent to a sun protection factor of approximately 10 [1]. UV protection by clothing depends on a large variety of factors, such as type of fibre, colour or moisture content [2]. In summer 1997, the Swiss Cancer League started to focus on these facts during the yearly sun protection campaign. A special education campaign under the title ‘How sunproof are your clothes?’ was initiated to gain public interest in 1997 and 1998. This campaign was also run by the health departments of 9 cities in the German federal state of Lower Saxony in summer 1998 and attracted significant attention in the media.During these campaigns the UV transmission of 1,604 items of clothing worn by passers-by was determined in 30 cities in Switzerland and 9 cities in Germany using a Labsphere® Transmittance Analyser UV-1000F (provided by Ciba Specialty Chemicals, Basel, Switzerland).With this portable instrument, a fabric is illuminated by a xenon flash inside an integrating sphere. The emission spectrum of the light source includes UVB and UVA and ranges from 250 to 450 nm.The fraction of light passing through the sample in a parallel beam is analysed spectrally by a diode array. Ultraviolet protection factors (UPF) were determined according to the Australian/New Zealand Standard as weighted UVR transmittance of Melbourne sunlight [3, 4].Figure 1 summarises the results by demonstrating the erythemally weighted UVR transmission in percent of the garments tested. These garments were mainly made of cotton, about 90% in Switzerland and 80% in Germany. Over 25% of the items did not fulfil the protective properties advocated by the Australian/New Zealand Standard (UPF <15). About one quarter each can be classified as providing ‘good protection’ (UPF 15–25), ‘very good protection’ (UPF 25–40) and ‘excellent protection’ (UPF >40) according to this standard. The data obtained during the three campaigns are comparable to measurements in Australia in 1994 [5].The results clearly show that a quarter of summer garments do not provide sufficient UV protection since fabrics with UPFs below 15 can easily let through UV doses higher than the minimal erythemal dose (MED) during outdoor activities around noon. For example, a UVR intensity of 0.5 W/m2 over 3 h will result in a dose higher than 1 MED for skin type II (damage threshold 0.25 kJ/m2). This irradiation intensity can be achieved in Germany during June/July or in the South of Spain and New York City from April through September, in Florida from February until November and in Townsville (Australia) all year round. This excess exposure to UV light due to insufficient protection by clothing might contribute to the skin cancer epidemic [6, 7]and to the induction of epithelial skin cancers and create health problems in patients suffering from photosensitive disorders such as lupus erythematosus, photo-allergies or chronic actinic dermatitis. UVR exposure could hence be simply reduced with special UV protective clothing [8]that normally guarantees a UPF of 30+, i.e. a weighted UVR transmission less than 3.3%. A label indicating the UPF rating might help to identify these products, especially for light-coloured and thin garments.The authors wish to thank the Swiss Cancer League and the German Health Departments that performed the UPF measurements during their skin cancer prevention activities.