Scientific journal publication Evidence from firn air for recent decreases in non-methane hydrocarbons and a 20th century increase in nitrogen oxides in the northern hemisphere. Worton, D.R.; Sturges, W.T.; Reeves, C.E.; Newland, M.J.; Penkett, S.A.; Atlas, E.; Stroud, V.; Johnson, K.; Schmidbauer, N.; Solberg, S.; Schwander, J.; Barnola, J.-M. Publication details Journal: Atmospheric Environment, 54, 592–602, 2012 DOI: 10.1016/j.atmosenv.2012.02.084