The flourishing business with siliceous earth, however, is overclouded by one peculiar flaw: silicosis, the occupational disease. This "dust lung" affection will be recognized and diagnosed in the years between 1920 and 1930. As soon as the causes of the illness have been identified, Franz and Felix Hoffmann, together with their inventive foreman Bayerle, start looking for solutions. The results are bags made out of silk tissue which are pulled over the head, and are furnished with fresh air from a compressor. In all likelihood, this is the very first fresh air mask in the world. At this time, no work protection regulations do exist to specify such protective measures, and all the same the mask will continually be improved. In fact, the investment into employees has always been regarded with Hoffmann as an investment into the future. Another important step towards the future is made in 1935. With an important local property owner, the foundation "Studienseminar Neuburg", a contract is signed for 50 years of exploiting rights of siliceous earth deposits to be found in the area.