“…4 Action spectra were thus determined already in the early research using artificial light sources and different types of filter. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Although wavelengths between 300 and 800 nm and even longer 12,19 have been reported, the action spectrum for most patients is between 300 and 500 nm. In 1942, Rajka 10 reported that solar urticaria could be passively transferred to normal volunteers by an intradermal injection of serum from a person with solar urticaria.…”