The method was used to confirm the structural repeat unit in natural rubber as isoprene. It is also a serious problem, known as "ozone cracking" where traces of the gas in an atmosphere will cut double bonds in susceptible elastomers, including natural rubber, polybutadiene, Styrene-butadiene and Nitrile rubber. Ozone cracking creates small cracks at right angles to the load in the surfaces exposed to the gas, the cracks growing steadily as attack continues.