An aerobiological survey of allergens in al Khobar, Saudi Arabia.

A nationwide aerobiologic study is in progress in Saudi Arabia using Burkard 7-day volumetric spore traps to determine the major airborne allergens and their seasonal patterns. Eights months readings have been completed at Al-Khobar, an important coastal city on the Arabian Gulf. Pollen levels showed a double season. An autumnal peak reached its maximum in October rising sharply from the low summer values before falling during the short winter then rising again in springtime. Both local and imported flora were represented with chenopodiaceae, grasses and Ambrosia as the most common botanical groups, identification of the most significant individual species is still in progress. Fungal spores also show distinctive seasonal patterns. In descending rank order from the most common genera were Cladosporium, Ustilago, Alternaria, with Chaetomium and Ulocladium as consistent but minor components. Basiodiospores and Ascospores represented less than 10% of the total spore population, indicative of the dry nature of the climate. Desert dust added an important irritant to the Saudi atmosphere but a major contaminating factor to the aerobiological material being analysed.