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

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, 0·9 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=0·52, p=0·034) as were annual cumulative increases in Tmin (r=0·61, p=0·010). Similar results were observed for pollen season duration, but only for cumulative degree days (higher than the freezing point [0°C or 32°F]) for Tmax (r=0·53, p=0·030) and Tmin (r=0·48, p=0·05). Additionally, temporal increases in frost-free days per year were significantly correlated with increases in both pollen load (r=0·62, p=0·008) and pollen season duration (r=0·68, p=0·003) 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-one that could be exacerbated as temperatures continue to increase. FUNDING: None.

Patient satisfaction with beclomethasone dipropionate nasal aerosol device with integrated dose counter during daily use.

Some patients with allergic rhinitis (AR) may prefer a "dry" intranasal corticosteroid aerosol to avoid certain sensory perceptions such as the "wet feeling in the nose" and the "dripping down the throat" associated with aqueous nasal sprays. A nonaqueous hydrofluoroalkane-propelled beclomethasone dipropionate (BDP) nasal aerosol with an established efficacy and safety profile was approved to treat the nasal symptoms associated with AR in adult and adolescent patients. This study was designed to evaluate ease of use and patient satisfaction with the BDP nasal aerosol device in patients with perennial AR (PAR). In this phase 3, randomized, double-blind, parallel-group, placebo-controlled study, eligible patients (≥12 years of age) with PAR were randomly assigned to receive BDP nasal aerosol at 320 micrograms/day or placebo for 6 weeks. At the end of the treatment period, patients assessed device ease of use and satisfaction with the device using a questionnaire with a 5-point representative scale (not at all, not very, neither nor, somewhat, very [certain/easy/satisfactory]). Nearly all patients (89.7%) reported that the BDP nasal aerosol device with integrated dose counter was "very easy" or "somewhat easy" to use. The majority of patients (87.5%) also indicated that it was "very easy" or "somewhat easy" to tell when the device was empty, compared with only 42.3% who were "very certain" or "somewhat certain" of being able to tell when previously used aqueous nasal spray devices were empty. Overall, patient satisfaction with the BDP nasal aerosol device was high: 65.7% responded that they were "very satisfied" or "somewhat satisfied" and only 3.6% were "not satisfied at all" or "not very satisfied." These results indicate that the majority of patients considered the BDP nasal aerosol device easy to use and reported a high degree of satisfaction with the device compared with other nasal sprays they had used in the past.

Recent warming by latitude associated with increased length of ragweed pollen season in central North America.

A fundamental aspect of climate change is the potential shifts in flowering phenology and pollen initiation associated with milder winters and warmer seasonal air temperature. Earlier floral anthesis has been suggested, in turn, to have a role in human disease by increasing time of exposure to pollen that causes allergic rhinitis and related asthma. However, earlier floral initiation does not necessarily alter the temporal duration of the pollen season, and, to date, no consistent continental trend in pollen season length has been demonstrated. Here we report that duration of the ragweed (Ambrosia spp.) pollen season has been increasing in recent decades as a function of latitude in North America. Latitudinal effects on increasing season length were associated primarily with a delay in first frost of the fall season and lengthening of the frost free period. Overall, these data indicate a significant increase in the length of the ragweed pollen season by as much as 13-27 d at latitudes above ~44°N since 1995. This is consistent with recent Intergovernmental Panel on Climate Change projections regarding enhanced warming as a function of latitude. If similar warming trends accompany long-term climate change, greater exposure times to seasonal allergens may occur with subsequent effects on public health.