It’s no surprise that plants can set off your allergies in the summer, but not all the plants are contributing to your inconvenience. Vokou and colleagues studied six urban green spaces in Thessaloniki, Greece, to see if the plants growing there matched the pollen found in the air. They counted all the trees and shrubs in each park and measured airborne pollen at breathing height, and found what you see is not what you breathe. The findings could help parks be designed to reduce allergy risks for visitors.
The researchers found that while some abundant park plants produced little airborne pollen, other types of pollen showed up in high concentrations despite having no parent plants nearby. Even parks close to each other had very different pollen patterns. However, in larger parks of around 40 hectares, and in spaces enclosed by tall buildings, the pollen in the air more closely matched the plants growing there.
The research team visited each green space weekly throughout 2020. Using portable vacuum-like samplers held at chest height, they collected air samples for 20 minutes during each visit. All six parks were sampled within two hours of each other to ensure fair comparisons. Back in the laboratory, they used microscopes to identify and count different types of pollen grains in each sample. They also did a thorough plant census, noting not just the species of every tree and shrub, but also whether plants that were pollen-producing males or not.
Climate scientists predict that pollen allergies will become more frequent and severe over the next twenty years, with climate change leading to higher pollen counts and longer pollen seasons. Previously, researchers thought they could assess allergy risks in parks just by surveying the plants growing there. This new study shows that approach isn’t enough – parks need actual pollen monitoring to understand exposure risks for visitors. With roughly one in four people affected by pollen allergies, this knowledge could help city planners create greener, healthier urban spaces.
Vokou, D., Charalampopoulos, A., Lazarina, M., Tsingani-Papanikolaou, O., Leontidou, K., Paschalidou, D., Damialis, A., & Hanlidou, E. 2024. Plants on the ground, pollen in the air: how much do they match? Aerobiologia. https://doi.org/10.1007/s10453-024-09838-6 ($)
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