ABSTRACT
Background: Grass pollen is one of the most important allergen sources inducing respiratory allergies and Phl p 5 allergen of timothy pollen is considered one of the major parts of the allergenic activity of grass pollen. In this study, we evaluated seasonal variation in the concentration of both grass pollen and Phl p 5 allergens as well as the ratio allergen/pollen (pollen potency) in the air of Bratislava, Slovakia during two consecutive years, 2019-2020. These two years differed in terms of air pollution, as COVID-19 lockdown in 2020 improved air quality in a very emphatic manner in the study area. Therefore, the goal of this research was also to determine how environmental factors affect airborne pollen and aeroallergen levels and pollen potency. Method: Pollen sampling was performed using a Hirst-type sampler, while a cyclone sampler was used for the aeroallergen capturing. Allergenic molecules were quantified by ELISA assay. Results: In 2020, the year characterised by a less polluted atmosphere due to COVID-19 lockdown, we observed significantly higher Seasonal Poaceae Pollen Integral, the mean daily pollen value and even peak pollen value, while the mean daily pollen potency, the mean daily allergen concentration and peak allergen value were significantly lower than in 2019. Raised pollen concentrations were accompanied by increased ozone and carbon monoxide levels in 2020, whereas increased rainfall or relative humidity led to the reduction of pollen in the atmosphere. In 2020, the aeroallergen levels were associated mainly with pollen, but nitrogen dioxide in the air could increase the number of allergens per pollen. In contrast, the aeroallergen levels were associated with carbon monoxide in 2019. Conclusion: Based on our results it is evident that air pollutants can influence grass plants to produce pollen with altered allergenic content.