A conflict between industrialization and worker health developed in the painting industry during the early 1900s with the introduction of the spray machine. This technological innovation allowed the application of paint at greater speed and lower cost than hand painting and increased the rate at which painters were exposed to lead and other toxins contained in paint. By the mid-1920s, the spray machine was being used by painters for a wide variety of work. Although workers had expressed growing concern over the safety of the spray gun since World War I, painters and union leaders began to formally organize opposition to the device in 1924. At the core of their resistance was the belief that the spray machine was indeed hazardous to the health of workers. The first official recognition of the hazard of spray painting came in 1924, when the Wisconsin Industrial Commission investigated the spray machine and established guidelines for the regulation of its use within the state. The commission recommended a variety of regulations setting restrictions on the type of spray equipment that could be used, established mandatory use of ventilation and safety devices, and outlined limits on the number of hours per day painters could use the machines.