Enrichment pathways of genes of S. cerevisiae which were significantly correlated with VOCs in response to PM exposure from 31 major Chinese cities. “(1)” and “(2)” represent monomer and dimer ions in the IMS, respectively. Some VOCs were labeled as Area # which means the GC-IMS library does not have an existing compound that matches the corresponding retention index and drift time. Their retention index and drift time were presented in Table S6.