ABSTRACT
Aims: The study was conducted to investigate the frequently encountered allergenic pollen grains in the environment of Riyadh, Saudi Arabia as well as to determine their seasonal and annual growth pattern in the region. Study Design: Volumetric air sampling of two City sites with qualitative and quantitative comparison of data on seasonal and diurnal concentrations of weed pollen aeroallergens. Place and Duration of Study: The work was conducted in the capital City of Riyadh, Saudi Arabia and the sampling was conducted for a continuous 12 month period from January to December 2012. Methodology: Using two Burkard 7-Day Volumetric Air Sampler, airborne pollen grain for two sites in Riyadh City (City Center site in the middle of City) and Riyadh airport site (40 km away from the city) was studied. The data were collected for at least 12 months period in both sites. Results: The pollen grains from grasses, weeds and trees were identified. However, the weeds pollen dominated the pollen flora by a ratio of 70% followed by trees 20%, and grasses 10%. The major weeds pollen identified were: Amaranthus viridis, Artemisia monosperma, Atriplex nummularia, Chenopodium murale, Plantago boissieri, Ricinus communis, Rumex vesicarius and Salsola imbricata. Riyadh City Center site constituted higher percentage of total weeds (69%) compared to Riyadh airport site (31%). Conclusion: Seasonal periodicities of major allergens, reveal a trend that would help allergists and allergic patients for diagnosis and prevention.