The invention concerns the use of test strips with a flat, preferably oblong foil which carries a matrix containing a photoactive chromogenic substance to pre-determine the duration of stay in the sun that is possible without sunburn, a test system for this determination containing test strips and a...http://www.google.de/patents/US5589398?utm_source=gb-gplus-sharePatent US5589398 - Use of test strips to determine the UV intensity or to pre-determine the duration of stay in the sun without sunburn
