The new finding declared epidermal growth factor receptor (EGFR) pathway was activated in lung cancer cells through short-term exposure to PM2.5 for 24 hours while long-term exposure in 90 days could enhance the transmembrane serine protease 2-IL18 (TMPRSS2-IL18) pathway that promotes tumor progression in lung cancer 26. Here, PRSS2 is linked to lung cancer.