One-Year pollen and spore calendars of Saudi Arabia: Al-Khobar, Abha and Hofuf Syed M. Hasnain 1, *, Khatija Fatima 2 , Abdulrahman Al-Frayh 2 and Sultan T. Al-Sedairy 1 1 Department of Biological and Medical Research (MBC-O3), King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh, 11211, Saudi Arabia 2 College of Medicine, King Saud University, Riyadh, Saudi Arabia (*Author for correspondence: E-mail: hasnain@kfshrc.edu.sa) (Received 14 June 2004; accepted 17 May 2005) Key words: allergens, airborne pollen and spores, Saudi Arabia Abstract Airborne Pollen grains and Spores of three different cities viz., Al-Khobar (1987–1988), Abha (1991–1992) and Hofuf (1992–1993) in Saudi Arabia were studied using Burkard Volumetric Seven-Day Spore Trap. The data were analyzed in relation to their allergenic capability and one-year pollen and spore calendars were designed to correlate the patients’ symptoms as well as for selection of appropriate allergen extracts for diagnosis and treatment of allergic diseases. Amongst pollen group, Amaranthus viridis, Plantago spp., Chenopodium album, Ricinus communis, Rumex vesicarius, Juniperus spp., Parkinsonia aculeata, Prosopis spp., and Phoenix dactylifera were some of the frequent types. Amongst the fungal spores group Clados- porium, Smuts spores, Colored basidiospores, Alternaria, Ulocladium and Drechslera were the dominant types. 1. Introduction Airborne bio-particles are a major cause of respiratory diseases in humans, causing allergies, asthma and pathogenic infections of respiratory tract. Airborne bio-particles include pollen grains from wind-pollinated plants, viruses, bacteria, spores of fungi, mosses, ferns, fungi hyphal frag- ments, algae and other plant fragments. Biologi- cal pollutants and the concentration of airborne allergens vary according to location, altitude, time of the day, season of the year and fluctuate with climatic conditions (e.g. rain, temperature, humidity and wind velocity etc.) (Al-Doory et al., 1980). Therefore, regional influences are more important in the elicitation of allergic symptoms. An allergen calendar compiled for each region of a country can be used in allergy clinics and hospitals for symptoms correlation and subsequent selection of allergens panel for diag- nosis and treatment. This also serves primary goal towards the prevention and control of envi- ronmental allergens. These calendars can be pre- pared by sampling one or more locations for at least 12-month period. Yearly variations in air- borne allergens of a region can be displayed by allowing the sampler to run for a longer period (i.e. two or more years) at one location. Aerobiological and clinical studies are gener- ally conducted simultaneously to establish the prevalence and possible contribution of allergens of outdoor and indoor origin in the etiology of allergic disorders, particularly bronchial asthma. In this regard some studies have already been conducted in Saudi Arabia (Sorenson et al.,1985 ; Al-Frayh et al., 1992, 1995, 2000, 2001; Hasnain et al., 1999a, b, 2004a, b; Al-Suwaine et al., 2001) and its neighboring countries: Kuwait Aerobiologia (2005) 21: 241–247 Ó Springer 2005 DOI 10.1007/s10453-005-9000-0