Transform OC to POM
CONV_OC_POMAn object of class numeric of length 1.
Kanakidou, M., Seinfeld, J.H., Pandis, S.N., Barnes, I., Dentener, F.J., Facchini, M.C., Dingenen, R.V., Ervens, B., Nenes, A.N.C.J.S.E., Nielsen, C.J. and Swietlicki, E., 2005. Organic aerosol and global climate modelling: a review. Atmospheric Chemistry and Physics, 5(4), pp.1053-1123.