 It is responsible for the photodegradation of many materials but can be put to constructive use in preparative organic chemistry and photodynamic therapy.Trace amounts of singlet oxygen are found in the upper atmosphere and also in polluted urban atmospheres where it contributes to the formation of lung-damaging nitrogen dioxide.It often appears and coexists confounded in environments that also generate ozone, such as pine forests with photodegradation of turpentine.