Fig. 1From: Early-life exposure to three size-fractionated ultrafine and fine atmospheric particulates in Beijing exacerbates asthma development in mature miceCharacteristics of PM. Scanning electron micrographs (a) and transmission electron microscopy (b) were used to characterize the external morphology and internal features of the fractions of collected particulate matter. c Typical TEM images and relevant EDX spectra of elemental mapping results of F1Back to article page