D2.513 - Weed pollen exposure in Almaty: aerobiological monitoring and component-resolved IgE sensitization patterns

Weed pollens are an important cause of seasonal allergic disease in Almaty. In urban settings, pollen exposure may coincide with air pollution, potentially increasing the clinical impact of seasonal allergy. However, local aerobiological data remain limited. We combined aerobiological monitoring in 2025 with routine clinical IgE sensitization data from Almaty (2019-2025) to describe pollen exposure patterns and sensitization profiles by age and sex.

In 2025, airborne pollen was monitored in Almaty using a Hirst-type volumetric Burkard sampler (10 L/min) with microscopic identification and counting; concentrations were expressed as grains/m3. Routine anonymized component-resolved specific IgE results from Almaty (2019-2025) were summarized for the most frequently positive components, including nArt v 1 (mugwort), nAmb a 1 (ragweed), rPhl p 1/rPhl p 5b (timothy) and rBet v 1 (birch). Sex and age-group distributions were reported as counts and proportions.

During July-October 2025, total airborne pollen (all taxa combined) was dominated by Artemisia (35.4%), followed by Ambrosia (27.0%) and Chenopodiaceae (15.6%). In August 2025, intraday patterns for total airborne pollen showed a peak at 10:00-14:00 (40% of the daily total), a secondary rise at 14:00-18:00 (22%), and minimal levels overnight and early morning. The mugwort pollen season began on 02 July 2025 and ended on 08 November 2025; high levels (>51 grains/m3) were observed from 03 July, and the maximum daily concentration reached 3517 grains on 22 September 2025. In the clinical dataset, among pollen-sensitized cases, weeds accounted for 82%; within the weed group, mugwort contributed 44% and ragweed 37%. The numbers of positive results were nArt v 1 n=355 (male 174, female 181) and nAmb a 1 n=296 (male 173, female 123); timothy markers were positive in n=103 (male 67, female 36) and birch rBet v 1 in n=33 (male 22, female 11). Sensitization was most frequent in 7-14 years for mugwort, ragweed and birch, whereas timothy peaked at 14-18 years.

Almaty shows a prolonged weed pollen season with pronounced daytime peaks, and routine IgE data indicate a high burden of weed sensitization dominated by mugwort and ragweed. Local pollen surveillance is particularly relevant in urban environments where pollen exposure may coincide with air pollution. Integrating aerobiology with component-resolved diagnostics can inform local pollen calendars, patient alerts, and timing of preventive and symptomatic treatment, with a focus on peak months and peak hours. These aerobiological findings are based on the 2025 season and warrant multi-season monitoring to refine local pollen calendars.