Objective Aeroallergen sampling is carried out by different devices and variable methods. The purpose of our study was to detect the common air pollens of Zanjan city.

Methods We provided a model 20 Rotorod sampler which is a small, portable device that is most often used for field research. Airborne pollen grains and particles larger than 3m in diameter could be captured at high efficiencies by that. Most patients who have been referred to allergy clinics had signs and symptoms especially at early morning and evening, thus we regulate our intermittent sampling strategy at the same times. We used duty cycle regulator. Therefore, our sampler has worked at 6.008.00 AM and 5.007.00 PM, concomitant with sunrise and sunset times. The sampler was installed near to meteorology devices in an aluminum cover and 150cm above the ground. Each transited and storage vial holds up 2612 collector rods and we collected rods weekly. After 6weeks we completed one vial for transport to laboratory for sample assessment. Each pair of rods has shown the one week pollen and 2 completed vials also could identify season airborne pollen.

Results The airborne pollens collected from June to October 2006 were studied mulberry, walnut, pillow, cottonwood and cedar tree family, grass and weeds pigweed and amaranth were common pollens of Zanjan and the concentration of them were 3226 per cubic meter of air.

Conclusions The pattern pollination in Zanjan was similar to other studies of the world but the pollination of grass was later in respect to similar temperate regions. This may be a factor for increasing the sensitivity of patients to this allergen.