Fig. 2From: Early-life exposure to three size-fractionated ultrafine and fine atmospheric particulates in Beijing exacerbates asthma development in mature miceThe proportion of PAH with different numbers of benzene rings in F1Â (a) and F2Â (b). The proportion of PAHs with two to six benzene rings was determined; the proportions of BAP, IND and DBA with five benzene rings, which may be associated with more severe toxicity, are also listed separately at the sideBack to article page