Diversity of Pollen Grains and Their Allergenic Potential at the Roshn Waterfront, Jeddah Corniche, Saudi Arabia

Jeddah, a prominent coastal city along the Red Sea in Saudi Arabia, has experienced significant urban growth, particularly around the Roshn Waterfront, a vital area for recreation and green spaces. Urban green spaces are known to boost biodiversity and enhance public health, but they may also pose allergenic risks due to the presence of airborne pollen. This study explores the variety of ornamental plants found at the Roshn Waterfront and examines the allergenic properties associated with their pollen. We identified 23 different plant species from 14 families along a 4-kilometre stretch from AlNawras Square to Atallah Happy Land Park. Each specimen was carefully classified, and pollen grains were collected from their flowers for detailed analysis. Pollen samples were treated with potassium hydroxide, stained with safranin-glycerin, and examined under a microscope. The pollen traits were documented in terms of size, shape, type of apertures, and surface ornamentation to ensure consistent results. For statistical analysis, a chi-square test was conducted to explore the relationship between exine texture and allergenic potential, and Principal Component Analysis (PCA) was used to illustrate the connections between pollen characteristics and allergy risks. The results showed that 60% of the pollen grains were spheroidal, 26% were prolate, and 87% were categorised as tricolpate. Regarding surface texture, 56% of the grains had a psilate exine, while 17% were echinate, and 13% displayed a reticulate structure. A significant link was established between surface features and allergenic potential (χ2 = 46. 46.00, p < 0. 001), indicating that pollen grains with echinate exines posed a high risk of causing allergies. The PCA analysis categorised the plant types into low, moderate, and high allergenic risk, highlighting species like Sphagneticola trilobata (L.) Pruski, Ipomoea pes-caprae (L.)R.Br., and Hibiscus rosa-sinensis L. are particularly concerning due to their spiny pollen structure. In conclusion, this research emphasizes that the physical characteristics of pollen, especially exine ornamentation and size, significantly affect allergenic responses and should be key considerations in urban gardening plans.