Background: Ambient air pollution is likely a risk factor for asthma, and recent evidence suggests the possible relevance of road traffic noise. Objectives: We examined the associations of long-term exposure to air pollution and road traffic noise with adult-asthma incidence. Methods: We followed 28,731 female nurses (age > 44 years) from the Danish Nurse Cohort, recruited in 1993 and 1999, for first hospital contact for asthma from 1977 until 2015. We estimated residential annual mean concentrations of particulate matter with diameter