( ( Their ( primary concern ) ) ( focused ( on ( air ( pollution ( -LRB- 36 ) ) ) ) ) )
(ROOT (S (NP (PRP$ Their) (JJ primary) (NN concern)) (VP (VBN focused) (PP (IN on) (NP (NP (NN air)) (NP (NNP pollution) (-LRB- -LRB-) (NNP 36)))))))
Their primary concern focused on air pollution (36
(ROOT (S (NP (JJ Primary) (NNS pollutants)) (VP (VBP enter) (NP (DT the) (NN air)) (ADVP (RB directly))) (. .)))