Background: There is limited information on risk factors for eczema in adults. Recent evidence suggests that air pollution may be associated with increased incidence of eczema in adults. We aimed to assess this possible association. Methods: Ambient air pollution exposures (distance from a major road, nitrogen dioxide [NO2], fine particulate matter with an aerodynamic diameter ≤2.5 µm [PM2.5]) were assessed for the residential address of Tasmanian Longitudinal Health Study participants at ages 43 and 53 years. Eczema incidence (onset after age 43 years), prevalence (at 53 years) and persistence were assessed from surveys, while sensitisation was assessed using skin prick tests. The presence or absence of eczema and sensitisation was classified into four groups: no atopy or eczema, atopy alone, non-atopic eczema, and atopic eczema. Adjusted logistic and multinomial regression models were fitted to estimate associations between ambient air pollution and eczema, and interaction by sex was assessed. Results: Of 3153 participants in both follow ups, 2369 had valid skin prick tests. For males, a 2.3 ppb increase in baseline NO2 was associated with increased risk of prevalent eczema (OR=1.15 [95%CI 0.98-1.36]), both non-atopic (OR=1.39 [1.02-1.90]) and atopic eczema (OR=1.26 [1.00-1.59]). These associations were not seen in females (P for interaction=0.08, <0.01). For both sexes, a 1.6 µg/m3 increase in PM2.5 exposure at follow-up was associated with increased odds of aeroallergen sensitisation (OR=1.15 [1.03-1.30]). Conclusion: Increased exposure to residential ambient air pollutants was associated with an increased risk of eczema, only in males, and aeroallergen sensitisation in both genders.