Development of a model to calculate asbestos fiber from damaged asbestos slates depending on the degree of damage

• Damaged slates emit asbestos fiber between 0.051 f/cc and 0.338 f/cc.
• This figure exceeds the indoor air quality standard established by up to 33.8 times.
• Damaged slates generate asbestos fiber of 0.159 f/cc per unit area of damaged slate.
• Emission of asbestos was 0.127 f/cc (Good), 0.157 f/cc (Normal), and 0.221 f/cc (Bad).

It is very important to quantify asbestos fiber emitted due to disasters and formulate measures to prevent scattering as to maintain, dismantle and remove asbestos slates effectively in normal times. The researchers developed a model to estimate the amount of asbestos fiber generated depending on the damage of slates, focusing on natural damages. The researchers collected used slates from typical buildings and classified them into 3 grades depending on the severity of damage. The researchers free-dropped slates from the roof height of a typical building, and sampled the air surrounding it. With the air sampled for each of the 3 grades of damage, the researchers counted the asbestos fibers by using the Scanning Electron Microscopy/Phase Contrast Microscopy. By conducting a regression analysis with SPSS 20.0 based on data acquired, the researchers deduced a formula. The linear regression analysis showed that ‘damaged slate generates asbestos fiber per unit area = 0.077 + 0.159 × area of slate (coefficient of determination: 70.1%)’. Generation of asbestos fiber per unit area was 0.127 f/cc (Good), 0.157 f/cc (Normal), and 0.221 f/cc (Bad). The estimation model offered in this study can quantify the amount of asbestos fiber based on the building area by estimating the amount of asbestos fiber scattered due to the slate's severity of damage. This estimation model is expected to contribute to the quantification of asbestos generated due to disasters, including earthquakes, by building and by area, which were not been possible before due to the lack of relevant studies.