BackgroundPollen allergens are one of the main contributors to the development and/or aggravation of allergic rhinitis, allergic conjunctivitis, and asthma.ObjectiveAn examination of the airborne pollen in residential areas should be conducted to aid the diagnosis and treatment of allergic diseases.MethodsAirborne pollen samples were collected from 2 sites in Incheon and 2 in Seoul from 2015 to 2016.ResultsThe highest monthly concentration of airborne pollen was observed in May and September each year. Pollen from 32 families and 50 genera was identified over the 2 years; of these, Pinus spp. showed the highest pollen concentration (41.6%), followed by Quercus spp. (25.3%), and Humulus spp. (15.3%), the latter of which had the highest concentration among weed pollen. The total pollen concentration was significantly higher in Incheon than in Seoul (p = 0.001 in 2015, p < 0.001 in 2016) and higher in 2016 than in 2015. The concentrations of pollen from weed species (Cupressaceae, Humulus spp., Artemisia spp., Ambrosia spp., and Chenopodiaceae) and grass species (Gramineae) were significantly higher (p < 0.001) than those from tree species. Pollen was distributed from February to November. The first pollen identified in both regions in each year was Alnus spp. Overall, the total concentration of Quercus spp., Betula spp., Humulus spp., Artemisia spp., Ambrosia spp., and Chenopodiaceae pollen increased significantly over the 2 years.ConclusionRegion-specific differences exist in the pollen of major allergenic plants. Continuous monitoring of pollen is thus essential for management of pollen-related allergic disorders in each region.