For a good part of the previous century, asbestos was frequently used in too many construction, industrial, and commercial applications to count. It was standard procedure to install in machine rooms, factories, and other similar area during construction, mostly over bare cement or wood flooring. It was also sometimes sprayed directly on the floors of these rooms, where high temperatures necessitated some kind of insulation.
Asbestos was used on machine room floors on a regular basis during the boom of the asbestos industry that started after World War II. Tiles made of asbestos were the most popular insulating material up until the 1970s because the price was so low and it was easy to get. In fact, any factory or building that has a machine room and was built before 1980 probably has asbestos tiles in the flooring, which could easily have released its dangerous fibers into the air over time.
Unfortunately, the public was largely unaware of the dangers of asbestos until the 1970s. But as factory and construction workers began to become ill from asbestos, many employers still kept the information to themselves and machine room floors remained full of dangerous asbestos. Some may still contain asbestos. Thousands of workers died from mesothelioma and other related diseases before the public was made aware of the dangers.