4 research outputs found

    Temperature-related changes in airborne allergenic pollen abundance and seasonality across the northern hemisphere : a retrospective data analysis

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    BACKGROUND: Ongoing climate change might, through rising temperatures, alter allergenic pollen biology across the northern hemisphere. We aimed to analyse trends in pollen seasonality and pollen load and to establish whether there are specific climate-related links to any observed changes. METHODS: For this retrospective data analysis, we did an extensive search for global datasets with 20 years or more of airborne pollen data that consistently recorded pollen season indices (eg, duration and intensity). 17 locations across three continents with long-term (approximately 26 years on average) quantitative records of seasonal concentrations of multiple pollen (aeroallergen) taxa met the selection criteria. These datasets were analysed in the context of recent annual changes in maximum temperature (T) and minimum temperature (T) associated with anthropogenic climate change. Seasonal regressions (slopes) of variation in pollen load and pollen season duration over time were compared to T, cumulative degree day T, T, cumulative degree day T, and frost-free days among all 17 locations to ascertain significant correlations. FINDINGS: 12 (71%) of the 17 locations showed significant increases in seasonal cumulative pollen or annual pollen load. Similarly, 11 (65%) of the 17 locations showed a significant increase in pollen season duration over time, increasing, on average, 0路9 days per year. Across the northern hemisphere locations analysed, annual cumulative increases in T over time were significantly associated with percentage increases in seasonal pollen load (r=0路52, p=0路034) as were annual cumulative increases in T (r=0路61, p=0路010). Similar results were observed for pollen season duration, but only for cumulative degree days (higher than the freezing point [0掳C or 32掳F]) for T (r=0路53, p=0路030) and T (r=0路48, p=0路05). Additionally, temporal increases in frost-free days per year were significantly correlated with increases in both pollen load (r=0路62, p=0路008) and pollen season duration (r=0路68, p=0路003) when averaged for all 17 locations. INTERPRETATION: Our findings reveal that the ongoing increase in temperature extremes (T and T) might already be contributing to extended seasonal duration and increased pollen load for multiple aeroallergenic pollen taxa in diverse locations across the northern hemisphere. This study, done across multiple continents, highlights an important link between ongoing global warming and public health-one that could be exacerbated as temperatures continue to increase. FUNDING: None

    Temperature-related changes in airborne allergenic pollen abundance and seasonality across the northern hemisphere: a retrospective data analysis

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    Summary: Background: Ongoing climate change might, through rising temperatures, alter allergenic pollen biology across the northern hemisphere. We aimed to analyse trends in pollen seasonality and pollen load and to establish whether there are specific climate-related links to any observed changes. Methods: For this retrospective data analysis, we did an extensive search for global datasets with 20 years or more of airborne pollen data that consistently recorded pollen season indices (eg, duration and intensity). 17 locations across three continents with long-term (approximately 26 years on average) quantitative records of seasonal concentrations of multiple pollen (aeroallergen) taxa met the selection criteria. These datasets were analysed in the context of recent annual changes in maximum temperature (Tmax) and minimum temperature (Tmin) associated with anthropogenic climate change. Seasonal regressions (slopes) of variation in pollen load and pollen season duration over time were compared to Tmax, cumulative degree day Tmax, Tmin, cumulative degree day Tmin, and frost-free days among all 17 locations to ascertain significant correlations. Findings: 12 (71%) of the 17 locations showed significant increases in seasonal cumulative pollen or annual pollen load. Similarly, 11 (65%) of the 17 locations showed a significant increase in pollen season duration over time, increasing, on average, 0路9 days per year. Across the northern hemisphere locations analysed, annual cumulative increases in Tmax over time were significantly associated with percentage increases in seasonal pollen load (r=0路52, p=0路034) as were annual cumulative increases in Tmin (r=0路61, p=0路010). Similar results were observed for pollen season duration, but only for cumulative degree days (higher than the freezing point [0掳C or 32掳F]) for Tmax (r=0路53, p=0路030) and Tmin (r=0路48, p=0路05). Additionally, temporal increases in frost-free days per year were significantly correlated with increases in both pollen load (r=0路62, p=0路008) and pollen season duration (r=0路68, p=0路003) when averaged for all 17 locations. Interpretation: Our findings reveal that the ongoing increase in temperature extremes (Tmin and Tmax) might already be contributing to extended seasonal duration and increased pollen load for multiple aeroallergenic pollen taxa in diverse locations across the northern hemisphere. This study, done across multiple continents, highlights an important link between ongoing global warming and public health鈥攐ne that could be exacerbated as temperatures continue to increase. Funding: None
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