Combined adjuvant effects of ambient vapor-phase organic components and particulate matter potently promote allergic sensitization and Th2-skewing cytokine and chemokine milieux in mice: The importance of mechanistic multi-pollutant research

•Vapor- and particle-phase air pollutants each enhance allergic sensitization.•Concurrent exposure to vapor and particles results in aggravated adjuvant effects.•Combined adjuvant effects of vapor and particles induces more robust allergic lung inflammation.•Co-exposure to vapor and particles creates a Th2-skewing milieu in the lungs of sensitized mice.