Interactions among Cupressaceae pollen, air pollutants and meteorology in the urban and suburban areas of Beijing, China

Atmospheric pollutants alter the physicochemical properties of pollen allergens, and raise a high risk of co-exposure to more aeroallergens in the allergic population. It is necessary to reveal the relationships between them and the impacts of meteorology on them both. Herein, synchronous data of aerobiology, pollution and meteorology at the same location are used to investigate the correlation between Cupressaceae pollen (major allergen in Norther China) and atmospheric pollutants, and their association with meteorological factors at different timescales in the urban and suburban areas of Beijing, China. In this research, the correlation between allergenic pollen, air pollutants and meteorological factors may display distinct patterns at daily and hourly timescales. Daily concentration of Cupressaceae pollen was positively correlated with PM_2.5 and O₃. Hourly pollen concentration exhibited positive correlation with NO_x and PM_2.5 during high-pollen episodes. Increasing temperature and decreasing relative humidity after sunrise facilitate pollination, causing hourly pollen peak. Temperature exhibited a strong positive correlation with daily and hourly O₃ concentrations. Highly humid conditions largely decreased allergenic pollen and O₃ concentrations but increased NO_x and PM_2.5 concentrations. In the urban area, local winds considerably impacting on hourly pollen peaks were associated with high levels of NO_x and PM_2.5. Concentration weighted trajectory (CWT) results indicated that allergenic pollen and O₃ may have some common potential source areas. This research will help us to get a better understanding of the linkage between allergenic pollen and air pollutants, and their dynamics under varying meteorological conditions, and provide effective support on addressing respiratory allergies on the risk of co-exposure for allergenic pollen and air pollutants in the urban and suburban areas of Beijing city.