Analysis of airborne pollen in Lebanon

Abstract

RATIONALE: Pollens are an important cause of respiratory allergies. Data regarding them is scarce in the Middle East and has never been assessed in Lebanon. A national aerobiology project was launched to develop a pollen calendar and set basis for future studies in the field of allergy. METHODS: Pollen sampling was performed with four volumetric Hirst samplers (VPPS, Lanzoni) located in the North, the South, the Bekaa Valley and Beirut the capital. Pollen identification and counting was gathered from all the sites in order to put together a pollen calendar for the whole year. RESULTS: A total of 81169 pollen grains/m3 were collected during the period extending from January to December 2008. The pollen of 36 plant species/genera/family were identified. The peak pollen concentration was in March. Arboreal plants constituted 83.5% of the total pollen grains, non-arboreal plants accounted for 9.7% and grasses 2.5%. The highest airborne presence was for the Cupressaceae (55.4%) followed by the Oleaceae (7.6%), Fagaceae (4.4%) and Salicaceae (4.1%). Among allergenically significant weeds, the most notable was Urticaceae (3.7%). It was present at high concentration eleven out of twelve months of the year. Poaceae constitutes one percent of the total pollen concentration. Its high season starts in March and ends in September. CONCLUSIONS: This is the first aerobiologic pollen data recorded in Lebanon at the national level. The results show that the Lebanese are exposed to high concentration of allergenic pollen throughout the year.