:::*According to a study by the University of Helsinki, coniferous forests--that is to say, those composed of trees such as pines--release nitrogen oxides into the atmosphere that combine with other pollutants to form smog. [http://www.findarticles.com/p/articles/mi_m1571/is_9_19/ai_100111682] | :::*According to a study by the University of Helsinki, coniferous forests--that is to say, those composed of trees such as pines--release nitrogen oxides into the atmosphere that combine with other pollutants to form smog. [http://www.findarticles.com/p/articles/mi_m1571/is_9_19/ai_100111682] |