Fig. 6.

Chemical composition varied among nPM batches collected from the same site at different times (Methods, Table 1). A) Water soluble organic carbons (WSOC); B) Alkali and alkaline-earth metals; C) Non-metals; and D) Post transition metals; E) Transition metals; F) endotoxin [32]; G) Normalized interquartile range of components and metal categories in nPM batches, showing magnitude of variation in different components. H) Hierarchical clustering of biological responses and chemical components of nPM batches, showing the degree of correlation. The dissimilarity matrix was calculated from Pearson correlation; clustering used average linkage method, which calculates the mean distance between elements of each cluster for further merging and degree of correlation.