Seasonal variation in the allergenic potency of airborne grass pollen in Bratislava (Slovakia) urban environment

The Phl p 5 allergen of the plant species Phleum pratense is considered one of the most crucial grass pollen allergenic molecules inducing respiratory allergies. 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 during two consecutive years, 2019-2020. These 2 years differed in terms of air pollution, as COVID-19 lockdown in spring 2020 considerably improved air quality in the study area. Air samples were collected using a Hirst-type sampler for pollen detection and the cyclone sampler for aeroallergen detection. In 2020, we observed 80.3% higher seasonal pollen integral, probably associated with the longer pollen season duration, however, 43.6% lower mean daily pollen potency than in 2019. The mean daily pollen value was 37.5% higher in 2020 than in the previous year, while the mean daily allergen value was 14.9% lower in 2020. To evaluate the relationship between the amount of pollen or allergen in the air and selected meteorological factors and air pollution parameters, we used multiple regression analysis. Regarding weather factors, precipitation and relative humidity were significantly associated with pollen and/or allergen concentration, though these associations were negative. Atmospheric pollutants, especially CO, NO2 and O-3 were significantly associated with pollen and/or allergen levels. The associations with CO and O-3 were positive, while the association with NO2 was negative. Our results indicate that for grasses, an air pollutant that has a significant positive relationship to the ratio of allergen/pollen is nitrogen dioxide.

Automated summary

Phl p 5 allergen from Phleum pratense, a crucial grass pollen allergenic molecule, was studied for seasonal variation in air concentration in Bratislava during 2019-2020, with notable air quality improvements in 2020 due to COVID-19 lockdown measures. The study found higher seasonal pollen levels but lower pollen potency in 2020 compared to 2019, with meteorological factors like precipitation and relative humidity negatively influencing pollen and allergen concentration. Pollutants like CO, NO2, and O-3 were also significantly associated with pollen and allergen levels, with nitrogen dioxide showing a significant positive relationship with the allergen/pollen ratio for grasses.