ement Asbestos sheet roofs are among the cheapest Goshala roofing alternative.  Are they safe ?

(Based on The Western Australian Advisory Committee on Hazardous Substances. 1990. Asbestos cement.)

Asbestos cement sheeting is not 100% asbestos. It is a cement sheet reinforced with typically 10-15% asbestos. The size of asbestos fibers affects their risk to human health. Fibers that can reach the smallest airways of the lungs (respirable fibers) pose the greatest risk. Larger fibers are removed by the body in various ways.

If left undisturbed, asbestos cement sheeting is considered to pose a negligible risk to your health because the asbestos fibers are bound in the cement.

Cracked or Damaged Sheeting: At the time asbestos cement sheeting is cracked or damaged, some respirable asbestos fibers can be released into the air. However, the number of released fibers is likely to be very low. This is because the material is not 100% asbestos, asbestos fibers in the sheeting are predominantly large and the asbestos is bound into the cement. Even if you are close to the material when it cracks or is damaged, it poses a very low health risk. The health risk reduces if you are further away. (More than one meter separation in the open can be considered safe)

After it is damaged/ chipped/cracked, asbestos cement sheeting does not continue to release significant asbestos fibers into the air. This is because the asbestos continues to be bound in the cement. To protect exposed edges from ongoing damage or fibre release, they can be painted or sealed.

Weathered Roofs: Over time, asbestos cement roofs will deteriorate. T he cement slowly breaks down and asbestos fibers are washed and blown away. Even if an asbestos cement roof is in poor condition, it is not likely to pose an increased risk to your health. Any released fibers rapidly disperse into the air and their concentration (the number of fibers in an amount of air) reduces within a short distance from the roof. Air testing near the ground has shown the concentration of fibers is very low, the same as if the asbestos cement roof was not there. Asbestos cement roofs can be left in place until they are no longer water tight. However, they can pose an increased risk to your health when they are disturbed or being worked on, especially with power tools or water blasters, or when the roof gutters are being cleaned. Precautions need to be taken at such times.