( ( All ( these pollutants ) ) ( ( are ( ( called ( primary pollutants ) ) ( because ( they ( are ( ( emitted directly ) ( into ( the atmosphere ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PDT All) (DT these) (NNS pollutants)) (VP (VBP are) (VP (VBN called) (NP (JJ primary) (NNS pollutants)) (SBAR (IN because) (S (NP (PRP they)) (VP (VBP are) (VP (VBN emitted) (ADVP (RB directly)) (PP (IN into) (NP (DT the) (NN atmosphere))))))))) (. .)))
All these pollutants are called primary pollutants because they are emitted directly into the atmosphere.
(ROOT (S (NP (JJ Primary) (NNS pollutants)) (VP (VBP enter) (NP (DT the) (NN air)) (ADVP (RB directly))) (. .)))