Each has varying potential impact on human health from crocidolite, with greatest impact, to chrysotile, with the lowest impact. Asbestos was very widely used throughout building construction, and daily life, from 1900 to the mid 1970's. An EPA national survey on asbestos, estimates that there are 1.2 billion square feet of friable spray-on asbestos alone in buildings across the country. There are a wide variety of diseases that are directly, or indirectly, associated with exposure to asbestos. These are principally related to inhaling, or ingesting, asbestos fibers or dust.
Most diseases appear many years after exposure.
Many of these diseases are terminal. These steps are arrayed roughly by cost and degree of effectiveness. The second approach is warning staff and users of possible asbestos exposure and actions to mitigate the hazards. These include respirators and exposure suits for maintenance workers, teaching safe handling practices, and installing signs and warnings. Routine air monitoring is also recommended to ensure air quality is within acceptable limits.