In this study, asbestos in air during dismantlement and removal of slate roof tiles and asbestos that could linger in mask filter and safety wear were investigated. In addition, a wetting agent and its physical properties for water were studied, while the possibility of prevention of drift was assessed based on the properties. According to the analysis of 100 air samples, asbestos concentrations ranged from 0.001 to 0.007 f/cc and the average was 0.002 f/cc. The concentrations of asbestos in all the samples were below 0.01 f/cc, emission limit for asbestos-removal facilities. The use of a wetting agent and the use of water were compared to analyze asbestos concentration in air during asbestos removal. According to the analysis, asbestos concentration was 0.002 f/cc on average with wetting agents and the concentration was 0.003 f/cc when water was used. The surface tension of wetting agents showed 28.9 to 42.1 mN/m range and the average was 34.9 mN/ m. The surface tension of tap water showed 72.2 mN/m. Water-absorption time was from 16 seconds to 300 seconds for wetting agents and the agents showed a significant difference with one another. Surface area on the roof tiles was measured by instillation of its spread. For wetting agents, the range was from 31.2 to 64.7 cm2, with the average of 40.6 cm2 and all wetting agents showed larger areas than tap water. Drying rate was measured for the assessment of wetting. According to the measurement, the rate ranged from 0.094 to 0.144 min−1 and 0.110 min−1 was the average. It was found that the drying rate of tap water was bigger than those of all the wetting agents, but some wetting agents did not show a big difference.