Safety of fiber cement board

Fire resistance

fiber cement cladding is a non-combustible material which is widely used in high bushfire prone areas 

While the best possible reaction to Fire Classifications are A1 (construction applications) and A1Fl (flooring applications) respectively, both of which mean "non-combustible" according to European standard EN 13501-1: 2007, as classified by a notified laboratory in Europe, some fiber cement boards only come with Fire Classification of A2 (limited combustibility) or even lower classifications, if they are tested at all.

Safety

As mentioned previously, long-term exposure to silica dust generated by cutting fiber cement siding during installation can lead to silicosis and other lung diseases among workers.Researchers at the US National Institute for Occupational Safety and Health (NIOSH) confirmed these findings, showing that many of the silica dust particles are in the respirable fraction, able to penetrate the deepest parts of the lung Laboratory tests performed by cutting fiber cement siding within an isolated chamber showed that by connecting a regular shop vacuum to a circular saw, exposures to silica dust produced by the cutting can be reduced by 80-90%.Later, NIOSH completed four field surveys where construction workers cut fiber cement siding. Results showed that exposure to silica dust was controlled below the NIOSH Recommended Exposure Limit (REL) for respirable crystalline silica (0.05 mg/m3) when a regular shop vacuum was used.

selected from: https://en.wikipedia.org/wiki/Fiber_cement_siding#Usage