Monitoring and perception of allergenic pollen in urban park environments

Urban green spaces are highly important for the health and well-being of urban residents, especially under conditions of ongoing climate change and urbanisation. However, vegetation in urban parks may also present a risk to human health through the presence of allergenic plants and release of allergy-inducing pollen. Using the city of Leipzig as a case study, we monitored pollen abundance in two inner city parks and on the roof of a central university hospital during the pollen season in 2021. We also conducted a questionnaire survey with 186 city residents. Questions related to their allergic symptoms, perceived physical and mental health impairment, potential behavioural adaptations due to expected pollen exposure, and suggestions for urban planning. We found nine plant genera with particularly high concentrations of pollen across the monitoring sites, including especially Alnus and Betula. While a high proportion of trees planted in one of the parks were Betula, potentially explaining the high concentrations we monitored, the high pollen load for Alnus could not be explained by the local presence of Alnus trees at either park. A majority of respondents (61%) indicated they suffered from pollen-related allergic symptoms, with Betula pollen most often mentioned as a main cause of their health impairment. Of respondents with symptoms, 82% indicated they did not change their park visitation patterns due to expected pollen exposure. However, nearly two-thirds of the respondents took allergy medication at least once per week. Participants’ recommendations for urban planning included considering allergies when selecting species for planting, improving urban air quality, and advancing public pollen information and warning systems. We conclude that particularly allergenic trees, such as Betula, should be avoided in densely populated urban areas, because of the potential for a large number of residents to experience allergy symptoms. However, such species should not be completely avoided, as plant diversity is still a crucial element of ecosystem resilience in the face of climate change and urbanisation. Combining objective and subjective data on the burden of allergenic pollen, as was done in our study, can help derive such targeted policy recommendations.