( ( As ( a result ) ) ( , ( ( harmful pollutants ) ( ( are ( released ( into ( the air ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN As) (NP (DT a) (NN result))) (, ,) (NP (JJ harmful) (NNS pollutants)) (VP (VBP are) (VP (VBN released) (PP (IN into) (NP (DT the) (NN air))))) (. .)))
As  a result, harmful pollutants are released into the air.
(ROOT (S (NP (NP (NNP Ash)) (SBAR (WHNP (WDT that)) (S (VP (VBZ enters) (NP (DT the) (NN air)) (PP (ADVP (RB naturally)) (IN as) (NP (NP (DT a) (NN result)) (PP (IN of) (NP (DT a) (NN volcano) (NN eruption))))))))) (VP (VBZ is) (VP (VBN classified) (PP (IN as) (NP (DT a) (JJ primary) (NN pollutant))))) (. .)))