A lean burn engine exhaust treatment articles comprising a low temperature lean NOx trap (LT-LNT) composition and methods for their use is disclosed. A lean burn engine exhaust gas treatment system including the lean burn engine exhaust treatment articles is also disclosed. The low temperature lean NOx trap (LT-LNT) compositions can comprise a washcoat layer on a carrier substrate, the washcoat layer including a platinum group metal component impregnated on a first support material comprising at least 50% alumina. The washcoat layer may further include a low temperature NOx storage material comprising a bulk particulate reducible metal oxide. Methods of monitoring the aging state of a lean burn oxidation catalyst in a lean burn engine catalyst system are also disclosed.