A: The sealant material consists of a water-based solution (65% water) prior to application. The dried sealant material primarily contains two chemicals, vinyl acetate polymer (VAP) and 2-ethyl-1 hexanol (2E1H). The vast majority of what is left in the duct system is VAP, which has been used in water-based paints, adhesives, and hair spray. VAP has been used in chewing gum, and has no OSHA Exposure Limit. 2E1H is a common industrial solvent and is not considered toxic by OSHA. A review of the literature showed no ill effects after long-term exposure to concentrations of 200 ppm. The largest concentration of 2E1H measured in test houses was 1 ppb (200,000 times smaller), during Aeroseal injection. The sealant is UL-listed for smoke generation and flame spread (UL 723 0,0), and additional testing by UL showed no signs of mold growth or erosion.