On the Use of Generalized Additive Models in Time-Series Studies of Air Pollution and Health.
( ( On ( ( the Use ) ( of Generalized ) ) ) ( Additive ( ( Models ( in ( ( Time-Series Studies ) ( of ( Air ( ( Pollution and ) Health ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN On) (NP (NP (DT the) (NN Use)) (PP (IN of) (NP (NNP Generalized))))) (NP (NNP Additive)) (VP (VBZ Models) (PP (IN in) (NP (NP (NNP Time-Series) (NNPS Studies)) (PP (IN of) (NP (NNP Air) (NNP Pollution) (CC and) (NNP Health)))))) (. .)))
Pollution does not occur in the air. 
( Pollution ( ( ( does not ) ( occur ( in ( the air ) ) ) ) . ) )
(ROOT (S (NP (NNP Pollution)) (VP (VBZ does) (RB not) (VP (VB occur) (PP (IN in) (NP (DT the) (NN air))))) (. .)))