Aerobiology and pollen allergy in Islamabad

ABSTRACT

Pollen allergies affect a significant proportion of Islamabad residents. Many patients with pollen allergy are hospitalised in Islamabad in spring [February to April], fall seasons [July to September], and after monsoons. To determine the type and concentration of airborne pollens causing allergic diseases in the susceptible patients in Islamabad. The study was conducted from January 2005 to December 2006 and 'Burkard Volumetric Spore Trap' provided by the World Allergy Organization was used. This spore trap was placed in the F-10 area of Islamabad and samples were collected on weekly basis during the whole study period. To obtain the sample, the spore trap drum was loaded with a strip of sticky tape every week. The sampled sticky tape was then collected each week at a specified time and replaced with a fresh strip of, sticky tape, which was then collected next week. This cycle continued for whole study period. From each sample seven permanent slides were made and mounted with gelevitol mounting media. The slides were then examined microscopically, A total of 702 individuals irrespective of age or gender were included in the study. Skin prick tests were performed for pollens using allergen extracts of Hollister-Steir, USA and the results were recorded. The two flowering seasons in Islamabad i.e., spring and fall caused maximum pollen allergies. The Broussonetia papyrifera [paper mulberry] tree in spring, and the Cannabis saliva [bhang] weed in the fall season, produced the highest seasonal pollen counts. In the spring season of 2005, Broussonetia papyrifera produced the highest pollen count, [73%] of the total pollen count, with a maximum count of 1390 pollen/cu meter of air/hour on 20th of March, while in 2006, it accounted for 75% of the total pollen count, with a maximum count of 1430 pollen/cu meter of air/hour on 10th of March. In fall season of 2005, Cannabis saliva produced maximum pollen counts of 85 pollens/cu meter of air/hr on 18th of August, while in 2006, it achieved maximum counts of only 40 pollens/cu meter of air/hr on 27th of August. Skin prick tests demonstrated that out of 702 individuals selected irrespectivc of age or gender, 338 [48%] exhibited positive results in response to Broussonetia papyrifera pollen extracts, 207 [29%] were positive to grass pollen extracts, and 137 [20%] were positive to Cannabis sativa pollen extracts. The Broussonetia papyrifera has the highest pollen count in the spring, [February to April], and is the main cause of allergic diseases like allergic rhinitis and asthma among the residents of Islamabad, while the Cannabis sativa pollen count peaks in the fall season, causing allergic symptoms from July to September. Skin prick tests confirmed the findings. Regular awareness campaigns for seasonal pollen allergy should be launched before the beginning of the seasons