Climate change effect on Betula (birch) and Quercus (oak) pollen seasons in the United States

Volunteerism Addressing Environmental Disparities in Allergy (VAEDIA): The presidential initiative to combat environmental injustice in allergy and immunology-a Work Group Report of the AAAAI VAEDIA task force

Many vulnerable people lose their health or lives each year as a result of unhealthy environmental conditions that perpetuate medical conditions within the scope of allergy and immunology specialists' expertise. While detrimental environmental factors impact all humans globally, the effect is disproportionately more profound in impoverished neighborhoods. Environmental injustice is the inequitable exposure of disadvantaged populations to environmental hazards. Professional medical organizations such as the American Academy of Allergy, Asthma & Immunology (AAAAI) are well positioned to engage and encourage community outreach volunteer programs to combat environmental justice. Here we discuss how environmental injustices and climate change impacts allergic diseases among vulnerable populations. We discuss pathways allergists/immunologists can use to contribute to addressing environmental determinants by providing volunteer clinical service, education, and advocacy. Furthermore, allergists/immunologists can play a role in building trust within these communities, partnering with other patient advocacy nonprofit stakeholders, and engaging with local, state, national, and international nongovernmental organizations, faith-based organizations, and governments. The AAAAI's Volunteerism Addressing Environmental Disparities in Allergy (VAEDIA) is the presidential task force aiming to promote volunteer initiatives by creating platforms for discussion and collaboration and by funding community-based projects to address environmental injustice.

Long-term trends and influence of climate and land-use changes on pollen profiles of a Mediterranean oak forest

Climate change is disrupting phenology and interaction patterns of natural ecosystems, but also human activities that modify land-uses have a direct impact, especially on species distribution and loss of biodiversity. The objective of this study is to evaluate the impact of climate and land-use changes on phenology and airborne pollen spectrum in a Mediterranean natural area, dominated by Quercus Forest and 'dehesa', in the South of the Iberian Peninsula. 61 different pollen types were identified over a 23-year period (1998-2020), mainly from trees and shrubs, such as Quercus, Olea, Pinus or Pistacia, and from herbaceous plants, such as Poaceae, Plantago, Urticaceae or Rumex. A comparison of pollen data from the first years of the study (1998-2002) up recent years (2016-2020), showed a substantial decrease in the relative abundance of pollen from autochthonous species associated with natural areas, such as Quercus or Plantago. However, the relative abundance of the pollen from cultivated ones such as Olea and Pinus, which is used for reforestation has increased. Regarding flowering phenology trends, our analyses revealed variations between -1.5 and 1.5 days per year. Taxa showing an advance phenology were Olea, Poaceae and Urticaceae, whereas Quercus, Pinus, Plantago, Pistacia or Cyperaceae experienced delayed pollination. Meteorological trends in the area generally resulted in an increase in both minimum and maximum temperatures, along with a decrease in precipitations. Changes in pollen concentration and phenology were correlated with changes in air temperatures and precipitation, although the positive or negative influence varied for each pollen type. The results suggest that climate change together with those motivated by land cover changes lead by human activities are having an impact on the phenology and pollen concentration, with the related consequences on pollination and therefore biodiversity more concerning in threatened areas as the Mediterranean Basin.

Phenological response to climate variation in a northern red oak plantation: Links to survival and productivity

In a changing climate, the future survival and productivity of species rely on individual populations to respond to shifting environmental conditions. Many tree species, including northern red oak (Quercus rubra), exhibit phenotypic plasticity, the ability to respond to changes in environmental conditions at within-generation time scales, through varying traits such as leaf phenology. Phenotypic plasticity of phenology may vary among populations within a species' range, and it is unclear if the range of plasticity is adequate to promote fitness. Here, we used a 58-year-old common garden to test whether northern red oak populations differed in phenological sensitivity to changes in temperature and whether differences in phenological sensitivity were associated with differences in productivity and survival (proxies of fitness). We recorded 8 years of spring leaf emergence and autumn leaf coloration and loss in 28 distinct populations from across the species' full range. Across the 28 populations, spring leaf out consistently advanced in warmer years, but fall phenology was less responsive to changes in temperature. Southern, warm-adapted populations had larger shifts in phenology in response to springtime warming but had lower long-term survival. Moreover, higher phenological sensitivity to spring warming was not strongly linked to increased productivity. Instead, fitness was more closely linked to latitudinal gradients. Although springtime phenological sensitivity to climate change is common across northern red oak populations, responses of productivity and survival, which could determine longer-term trajectories of species abundance, are more variable across the species' range.

Germplasm Resources of Oaks (Quercus L.) in China: Utilization and Prospects

Oaks exhibit unique biological characteristics and high adaptability to complex climatic and soil conditions. They are widely distributed across various regions, spanning 40 degrees latitude and 75 degrees longitude. The total area of oak forest in China is 16.72 million hm². There are 60 lineages of Quercus in China, including 49 species, seven varieties, and four subgenera. Archaeological data indicate that oaks were already widely distributed in ancient times, and they are dominant trees in vast regions of China's forests. In addition, the acorn was an important food for ancestral humans, and it has accompanied human civilization since the early Paleolithic. Diverse oak species are widely distributed and have great functional value, such as for greening, carbon sequestration, industrial and medicinal uses, and insect rearing. Long-term deforestation, fire, diseases, and pests have led to a continuous decline in oak resources. This study discusses the Quercus species and their distribution in China, ecological adaptation, and the threats facing the propagation and growth of oaks in a changing world. This will give us a better understanding of Quercus resources, and provide guidance on how to protect and better utilize germplasm resources in China. The breeding of new varieties, pest control, and chemical and molecular research also need to be strengthened in future studies.

Pollen Allergy in a Changing Planetary Environment

Airborne pollens are one of the common causative and triggering agents of respiratory allergy in a changing planetary environment. A growing number of people worldwide are contracting allergic diseases caused by pollens. The seasonal variations in pollens have occurred everywhere and the sensitization rate to pollens has increased in children as well as in adults. Moreover, allergenic plants, such as ragweed and Japanese hop, grow in soil damaged by human’s activities and deforestation with air pollution. It is impossible to avoid plants that cause allergies, because pollens can travel many kilometers in the breeze or wind. Hence, it is essential to survey and forecast pollens for the management of pollen allergy. Weather conditions may alter pollen concentrations. A number of studies have shown that increases in CO₂ concentration and atmospheric temperature raise pollen concentration. Hence most of the studies on the impact of climate change on aeroallergens must include the amount and allergenicity of pollens. It is yet unknown whether complex interactions with pollens, meteorological variables, and air pollutants in the changing environment. Considering the effect of climate change on the long-term trends in pollen levels and emerging viral infection, it is crucial to forecast and eliminate the associated risk for human health in future and take appropriate measures to reduce it.

Targeting immunodominant Bet v 1 epitopes with monoclonal antibodies prevents the birch allergic response

BACKGROUND

Blocking the major cat allergen, Fel d 1, with mAbs was effective in preventing an acute cat allergic response.

OBJECTIVES

This study sought to extend the allergen-specific antibody approach and demonstrate that a combination of mAbs targeting Bet v 1, the immunodominant and most abundant allergenic protein in birch pollen, can prevent the birch allergic response.

METHODS

Bet v 1-specific mAbs, REGN5713, REGN5714, and REGN5715, were isolated using the VelocImmune platform. Surface plasmon resonance, x-ray crystallography, and cryo-electron microscopy determined binding kinetics and structural data. Inhibition of IgE-binding, basophil activation, and mast cell degranulation were assessed via blocking ELISA, flow cytometry, and the passive cutaneous anaphylaxis mouse model.

RESULTS

REGN5713, REGN5714, and REGN5715 bind with high affinity and noncompetitively to Bet v 1. A cocktail of all 3 antibodies, REGN5713/14/15, blocks IgE binding to Bet v 1 and inhibits Bet v 1- and birch pollen extract-induced basophil activation ex vivo and mast cell degranulation in vivo. Crystal structures of the complex of Bet v 1 with immunoglobulin antigen-binding fragments of REGN5713 or REGN5715 show distinct interaction sites on Bet v 1. Cryo-electron microscopy reveals a planar and roughly symmetrical complex formed by REGN5713/14/15 bound to Bet v 1.

CONCLUSIONS

These data confirm the immunodominance of Bet v 1 in birch allergy and demonstrate blockade of the birch allergic response with REGN5713/14/15. Structural analyses show simultaneous binding of REGN5713, REGN5714, and REGN5715 with substantial areas of Bet v 1 exposed, suggesting that targeting specific epitopes is sufficient to block the allergic response.

Aerobiological modeling I: A review of predictive models

The present work is the first of two reviews on applied modeling in the field of aerobiology. The aerobiological predictive models for pollen and fungal spores, usually defined as predictive statistical models, will, amongst other objectives, forecast airborne particles' concentration or dynamical behavior of the particles. These models can be classified into Observation Based Models (OBM), Phenological Based Models (PHM), or OTher Models (OTM). The aim of this review is to show, analyze and discuss the different predictive models used in pollen and spore aerobiological studies. The analysis was performed on published electronic scientific articles from 1998 to 2016 related to the type of model, the taxa and the modelled parameters. From a total of 503 studies, 55.5% used OBM (44.8% on pollen and 10.7% on fungal spores), 38.5% PHM (all on pollen) and 6% OTM (5.4% on pollen and 0.6% on fungal spores). OBM have been used with high frequency to forecast concentration. The most frequent model of OBM was linear regression (18.5% out of 503) on pollen and artificial neural networks (4.6%) on fungal spores. In the PHM, the principal use was to characterize the main pollen season (flowering season) based on the model of growth degree days. Finally, OTM have been used to estimate concentrations at unmonitored areas. Olea (14,5%) on pollen and Alternaria (4,8%) on fungal spores were the taxa most frequently modelled. Daily concentration was the most modelled parameter by OBM (25.2%) and season start day by PHM (35.6%). The PHM approaches include greater model diversity and use fewer independent variables than OBM. In addition, PHM show to be easier to apply than OBM; however, the wide range of criteria to define the parameters to use in PHM (e.g.: pollination start day) makes that each model is used with a lesser frequency than other models.

A systematic review of the effects of temperature and precipitation on pollen concentrations and season timing, and implications for human health

Climate and weather directly impact plant phenology, affecting airborne pollen. The objective of this systematic review is to examine the impacts of meteorological variables on airborne pollen concentrations and pollen season timing. Using PRISMA methodology, we reviewed literature that assessed whether there was a relationship between local temperature and precipitation and measured airborne pollen. The search strategy included terms related to pollen, trends or measurements, and season timing. For inclusion, studies must have conducted a correlation analysis of at least 5 years of airborne pollen data to local meteorological data and report quantitative results. Data from peer-reviewed articles were extracted on the correlations between seven pollen indicators (main pollen season start date, end date, peak date, and length, annual pollen integral, average daily pollen concentration, and peak pollen concentration), and two meteorological variables (temperature and precipitation). Ninety-three articles were included in the analysis out of 9,679 articles screened. Overall, warmer temperatures correlated with earlier and longer pollen seasons and higher pollen concentrations. Precipitation had varying effects on pollen concentration and pollen season timing indicators. Increased precipitation may have a short-term effect causing low pollen concentrations potentially due to "wash out" effect. Long-term effects of precipitation varied for trees and weeds and had a positive correlation with grass pollen levels. With increases in temperature due to climate change, pollen seasons for some taxa in some regions may start earlier, last longer, and be more intense, which may be associated with adverse health impacts, as pollen exposure has well-known health effects in sensitized individuals.

Analysis of changes in Betula pollen season start including the cycle of pollen concentration in atmospheric air

Birch belongs to the most important allergenic taxa in Europe, therefore information on the start dates of the pollen season is very important for allergists and their patients as well as for climatologists. The study examined changes in the start of the birch pollen season as well as determined the trend of these changes. Pollen monitoring was performed in Lublin (eastern Poland) in the period 2001-2019 using the volumetric method. The Makra-test was used to detect periods with significantly higher or lower average of the onset than the average for the whole dataset. Two significant falls in the average of the pollen season start were found in 2007 and 2014. Besides, taking into account the 2-3-year rhythm of high and low concentrations of birch pollen in the atmospheric air, linear trends were fitted for the subsets of high and low abundance seasons. Significant changes in Betula pollen season start dates were only determined for the highly abundance seasons, while the results for seasons with a low concentration did not allow rejecting the hypothesis about the lack of a linear trend in the changes in the studied parameter. Moreover, a significant polynomial relationship was found between the beginning of a pollen season and the average values of monthly temperatures preceded a season. These analyses show that the start dates of the Betula pollen season are getting significantly earlier. The dynamics of changes differ between seasons with high and low concentrations of pollen.

Short term physician visits and medication prescriptions for allergic disease associated with seasonal tree, grass, and weed pollen exposure across the United States

BACKGROUND

While year-round exposure to pollen is linked to a large burden of allergic diseases, location-specific risk information on pollen types and allergy outcomes are limited. We characterize the relationship between acute exposure to tree, grass and weed pollen taxa and two allergy outcomes (allergic rhinitis physician visit and prescription allergy medication fill) across 28 metropolitan statistical areas (MSA) in the United States.

METHODS

We obtained daily pollen data from National Allergy Bureau (NAB) monitors at these 28 MSAs for 2008-2015. We revised the NAB guidelines to classify taxa-specific pollen severity each day. Daily information on allergic rhinitis and prescribed allergy medications for individuals with employer-based health insurance from the IBM MarketScan Research database for these MSAs. We combined the daily pollen and health data for each MSA into a longitudinal dataset. We conducted a MSA-specific conditional quasi-Poisson regression analysis to assess how different levels of pollen concentration impact the health outcomes, controlling for local air pollution, meteorology and Influenza-like illness (ILI). We used a random effects meta-analysis to produce an overall risk estimate for each pollen type and health outcome.

RESULTS

The seasonal distribution of pollen taxa and associated health impacts varied across the MSAs. Relative risk of allergic rhinitis visits increased as concentrations increased for all pollen types; relative risk of medication fills increased for tree and weed pollen only. We observed an increase in health risk even on days with moderate levels of pollen concentration. 7-day average concentration of pollen had stronger association with the health outcomes compared to the same-day measure. Controlling for air pollution and ILI had little impact on effect estimates.

CONCLUSION

This analysis expands the catalogue of associations between different pollen taxa and allergy-related outcomes across multiple MSAs. The effect estimates we present can be used to project the burden of allergic disease in specific locations in the future as well inform patients with allergies on impending pollen exposure.

Increased duration of pollen and mold exposure are linked to climate change

Pollen and molds are environmental allergens that are affected by climate change. As pollen and molds exhibit geographical variations, we sought to understand the impact of climate change (temperature, carbon dioxide (CO₂), precipitation, smoke exposure) on common pollen and molds in the San Francisco Bay Area, one of the largest urban areas in the United States. When using time-series regression models between 2002 and 2019, the annual average number of weeks with pollen concentrations higher than zero increased over time. For tree pollens, the average increase in this duration was 0.47 weeks and 0.51 weeks for mold spores. Associations between mold, pollen and meteorological data (e.g., precipitation, temperature, atmospheric CO₂, and area covered by wildfire smoke) were analyzed using the autoregressive integrated moving average model. We found that peak concentrations of weed and tree pollens were positively associated with temperature (p < 0.05 at lag 0–1, 0–4, and 0–12 weeks) and precipitation (p < 0.05 at lag 0–4, 0–12, and 0–24 weeks) changes, respectively. We did not find clear associations between pollen concentrations and CO₂ levels or wildfire smoke exposure. This study’s findings suggest that spore and pollen activities are related to changes in observed climate change variables.

Treatment Effect of the Tree Pollen SLIT-Tablet on Allergic Rhinoconjunctivitis During Oak Pollen Season

BACKGROUND

Birch, alder, hazel, and oak are members of the birch homologous group based on cross-reactivity toward the birch pollen allergen Betula verrucosa 1. Theoretically, allergy to these tree pollens may be treated by immunotherapy with one representative allergen extract.

OBJECTIVE

To evaluate post hoc whether treatment of birch pollen-induced allergic rhinoconjunctivitis with a standardized tree sublingual immunotherapy (SLIT)-tablet containing birch pollen extract reduces symptoms and symptom-relieving medication use during the oak pollen season (OPS).

METHODS

In a randomized, multinational, double-blind trial (EudraCT-2015-004821-15), 634 participants (ages 12-65 years) received daily tree SLIT-tablet (12 SQ-Bet) or placebo before and during tree pollen season (alder/hazel plus birch pollen season [BPS]). Symptom-relieving medication was allowed. The primary end point was the average total combined score (sum of rhinoconjunctivitis daily symptom score and daily medication score) during BPS. Outcomes during the OPS (excluding overlapping BPS days) were analyzed post hoc.

RESULTS

Relative improvements in average total combined score, daily symptom score, and daily medication score with the tree SLIT-tablet versus placebo during the OPS were 25%, 22%, and 32%, respectively (all P < .001). Significant correlations were observed between birch and oak serum immunoglobulin E (sIgE) at baseline (r = 0.86) and between birch and oak IgG₄ after treatment (r = 0.72). Oak sIgE and IgG₄ kinetics in response to tree SLIT-tablet treatment were similar to birch.

CONCLUSIONS

The tree SLIT-tablet leads to significant improvement of rhinoconjunctivitis outcomes during the OPS, supporting the clinical relevance of immunological cross-reactivity toward birch and oak allergens.

Amaranthaceae pollen grains as indicator of climate change in Lublin (Poland)

Previous studies have demonstrated that plants are a very good indicator of global environmental variations. The responses of many plant species to climate change are confirmed by aerobiological research. This paper presents an analysis of many parameters of pollen seasons in the Amaranthaceae family based on measurements of pollen concentrations in atmospheric air. Pollen samples were collected with the volumetric method at a sampling site in Lublin (Poland) in 2001-2019. The obtained data were verified using statistical analyses. Moreover, the presence of pollenkitt on the pollen grain surface was examined in fresh anthers using scanning electron and light microscopes, since there are some difficulties in identification of Amaranthaceae pollen grains deposited on microscopic slides in aerobiological analysis. The pollen season in Amaranthaceae began on average on June 23 and ended on October 5, i.e. it lasted 105 days. The peak value and annual pollen sum were characterized by the highest variability in the study years in comparison with other season characteristics. The annual pollen sum was in the range from 183 to 725. Maximum concentrations were most often recorded in the second half of August, which is associated with the greatest risk of development of pollen allergy symptoms in sensitive subjects during this period. The results obtained in the 19-year study revealed that the pollen seasons began 14 days earlier. Similarly, the end of the season was accelerated by 24 days. The response of these plants to climate change also include the reduced pollen production by representatives of this family, which was manifested by a decrease in the annual sum of daily airborne pollen concentrations, on average by 35%, and a reduction in the maximum pollen concentration, on average by more than 60%. We found that temperature in May and June had an effect on pollen release, and relative air humidity in May influenced pollen concentrations. We noted significant similarities in the pollen release rate during the last 8 years of the study. The scanning electron microscopy examinations showed that the pollen grain surface in the representative of this family was covered completely or partially with pollenkitt. Hence, the apertures characteristic for pollen in this family were poorly visible. The presence of pollenkitt on the surface of these polyaperturate pollen grains may play an important role in preventing water loss during pollen migration in the air. Our research has demonstrated the response of plants flowering in summer to climate change. The results not only have practical importance for public health in the aspect of allergy risk but can also help to assess environmental changes.

Allergy to oak pollen in North America

Background: Oak pollen is an important allergen in North America. The genus Quercus (oak) belongs to the family Fagaceae under the order Fagales. Objective: The objective of this article was to narratively review the oak pollen season, clinical and epidemiologic aspects of allergy to oak pollen, oak taxonomy, and oak allergen cross-reactivity, with a focus on the North American perspective. Methods: A PubMed literature review (no limits) was conducted. Publications related to oak pollen, oak-related allergic rhinitis with or without conjunctivitis, and oak-related allergic asthma were selected for review. Results: Oak species are common throughout the United States and contribute up to 50% to overall atmospheric pollen loads. Mean peak oak pollen counts can reach >2000 grains/m³. The start of the oak pollen season generally corresponds to the seasonal shift from winter to spring based on latitude and elevation, and may begin as early as mid February. The duration of the season can last > 100 days and, in general, is longer at lower latitudes. In the United States, ∼30% of individuals with allergy are sensitized to oak. The oak pollen season correlates with increased allergic rhinitis symptom-relieving medication use and asthma-related emergency department visits or hospitalizations. Oak falls within the birch homologous group. Extensive immunologic cross-reactivity has been demonstrated between oak pollen and birch pollen allergens, and, more specifically, their major allergens Que a 1 and Bet v 1. The cross-reactivity between oak and birch has implications for allergy immunotherapy (AIT) because guidelines suggest selecting one representative allergen within a homologous group for AIT, a principle that would apply to oak. Conclusion: Allergy to oak pollen is common in North America and has a substantial clinical impact. Oak pollen allergens are cross-reactive with birch pollen allergens, which may have implications for AIT.

Allergenic Pollen Season Variations in the Past Two Decades Under Changing Climate in the United States

Prevalence of allergic diseases has been increasing due to multiple factors, among which climate change has had the most impact. Climate factors increase production of pollen, which also exhibits increased allergenicity. Also, as a result of climate change, there has been a shift in flowering phenology and pollen initiation causing prolonged pollen exposure. Various numerical models have been developed to understand the effect of climate change on pollen emission and transport and the impact on allergic airway diseases.

Climate Change and Extreme Weather Events in Australia: Impact on Allergic Diseases

Several climate change-related predictions and observations have been documented for the Australian continent. Extreme weather events such as cycles of severe drought and damaging flooding are occurring with greater frequency and have a severe impact on human health. Two specific aspects of climate change affecting allergic and other respiratory disorders are outlined: firstly, the consequences of extreme weather events and secondly, the change in distribution of airborne allergens that results from various climate change factors.

The Role of Extreme Weather and Climate-Related Events on Asthma Outcomes

Extreme weather and climate events are likely to increase in frequency and severity as a consequence of global climate change. These are events that can include flooding rains, prolonged heat waves, drought, wildfires, hurricanes, severe thunderstorms, tornadoes, storm surge, and coastal flooding. It is important to consider these events as they are not merely meteorologic occurrences but are linked to our health. We aim to address how these events are interconnected with asthma outcomes associated with thunderstorm asthma, pollen production, mold infestation from flooding events, and poor air quality during wildfires.

Influence of climate change on flowering season of birch in the Czech Republic

This paper analyzes a long-term (1991-2019) flowering period of birch in the Czech Republic. Temporal and spatial evaluation in timing of beginning and end of flowering (F_begin and F_end) and flowering period (F_period) of Betula pendula were investigated in different zones of the Czech Republic. The field observations were carried out at 44 sites of the Czech Hydrometeorological Institute phenological network; the detailed analysis including growing degree days (GDD) evaluation to F_begin and F_end onsets and time of flowering were made at 9 sites in different altitudes. The trends and Pearson's correlation coefficients between F_begin (F_end) and GDDs were calculated as well. The timing of both phenological stages showed a significant advance to earlier onsets (e.g., - 7.0 d per decade at Měděnec station) and the time of flowering shortens (e.g., - 3.8 d per decade at Rokytnice station). Nevertheless, the most marked shift was observed for mountain area in the north-western and north-eastern part of the Czech Republic. In contrast, the smallest shift was found in the southern part of the Czech Republic. The shift of the GDD values fluctuates from negative to positive values. Pearson's correlation coefficients calculated for both phenophases and period of flowering of Betula pendula showed the highest values in F_period (e.g., 0.846 at Modrava station) and in F_end (e.g., 0.711 at Rokytnice station) as well. Thus, our results indicate due to global warming symptoms that birch pollen allergy may appear earlier in the year but for a shorter period.

Pollen calendars and maps of allergenic pollen in North America

Pollen is a common allergen that causes significant health and financial impacts on up to a third of the population of the USA. Knowledge of the main pollen season can improve diagnosis and treatment of allergic diseases. Our objective in this study is to provide clear, quantitative visualizations of pollen data and make information accessible to many disciplines, in particular to allergy sufferers and those in the health field. We use data from 31 National Allergy Bureau (NAB) pollen stations in the continental USA and Canada from 2003 to 2017 to produce pollen calendars. We present pollen season metrics relevant to health and describe main pollen season start and end dates, durations, and annual pollen integrals for specific pollen taxa. In most locations, a small number of taxa constitute the bulk of the total pollen concentration. Start dates for tree and grass pollen season depend strongly on latitude, with earlier start dates at lower latitudes. Season duration is correlated with the start dates, such that locations with earlier start dates have a longer season. NAB pollen data have limited spatiotemporal coverage. Increased spatiotemporal monitoring will improve analysis and understanding of factors that govern airborne pollen concentrations.

Impact of weather and climate change with indoor and outdoor air quality in asthma: A Work Group Report of the AAAAI Environmental Exposure and Respiratory Health Committee

Weather and climate change are constant and ever-changing processes that affect allergy and asthma. The purpose of this report is to provide information since the last climate change review with a focus on asthmatic disease. PubMed and Internet searches for topics included climate and weather change, air pollution, particulates, greenhouse gasses, traffic, insect habitat, and mitigation in addition to references contributed by the individual authors. Changes in patterns of outdoor aeroallergens caused by increasing temperatures and amounts of carbon dioxide in the atmosphere are major factors linked to increased duration of pollen seasons, increased pollen production, and possibly increased allergenicity of pollen. Indoor air pollution threats anticipated from climate changes include microbial and mold growth secondary to flooding, resulting in displacement of persons and need for respiratory protection of exposed workers. Air pollution from indoor burning of mosquito repellants is a potential anticipatory result of an increase in habitat regions. Air pollution from fossil fuel burning and traffic-related emissions can alter respiratory defense mechanisms and work synergistically with specific allergens to enhance immunogenicity to worsen asthma in susceptible subjects. Community efforts can significantly reduce air pollution, thereby reducing greenhouse gas emission and improving air quality. The allergist's approach to weather pattern changes should be integrated and anticipatory to protect at-risk patients.

Estimates of Present and Future Asthma Emergency Department Visits Associated With Exposure to Oak, Birch, and Grass Pollen in the United States

Pollen is an important environmental cause of allergic asthma episodes. Prior work has established a proof of concept for assessing projected climate change impacts on future oak pollen exposure and associated health impacts. This paper uses additional monitor data and epidemiologic functions to extend prior analyses, reporting new estimates of the current and projected future health burden of oak, birch, and grass pollen across the contiguous United States. Our results suggest that tree pollen in the spring currently accounts for between 25,000 and 50,000 pollen-related asthma emergency department (ED) visits annually (95% confidence interval: 14,000 to 100,000), roughly two thirds of which occur among people under age 18. Grass pollen in the summer season currently accounts for less than 10,000 cases annually (95% confidence interval: 4,000 to 16,000). Compared to a baseline with 21st century population growth but constant pollen, future temperature and precipitation show an increase in ED visits of 14% in 2090 for a higher greenhouse gas emissions scenario, but only 8% for a moderate emissions scenario, reflecting projected increases in pollen season length. Grass pollen, which is more sensitive to changes in climatic conditions, is a primary contributor to future ED visits, with the largest effects in the Northeast, Midwest, and Southern Great Plains regions. More complete assessment of the current and future health burden of pollen is limited by the availability of data on pollen types (e.g., ragweed), other health effects (e.g., other respiratory disease), and economic consequences (e.g., medication costs).

Herbarium specimens reveal substantial and unexpected variation in phenological sensitivity across the eastern United States

Phenology is a key biological trait that can determine an organism's survival and provides one of the clearest indicators of the effects of recent climatic change. Long time-series observations of plant phenology collected at continental scales could clarify latitudinal and regional patterns of plant responses and illuminate drivers of that variation, but few such datasets exist. Here, we use the web tool CrowdCurio to crowdsource phenological data from over 7000 herbarium specimens representing 30 diverse flowering plant species distributed across the eastern United States. Our results, spanning 120 years and generated from over 2000 crowdsourcers, illustrate numerous aspects of continental-scale plant reproductive phenology. First, they support prior studies that found plant reproductive phenology significantly advances in response to warming, especially for early-flowering species. Second, they reveal that fruiting in populations from warmer, lower latitudes is significantly more phenologically sensitive to temperature than that for populations from colder, higher-latitude regions. Last, we found that variation in phenological sensitivities to climate within species between regions was of similar magnitude to variation between species. Overall, our results suggest that phenological responses to anthropogenic climate change will be heterogeneous within communities and across regions, with large amounts of regional variability driven by local adaptation, phenotypic plasticity and differences in species assemblages. As millions of imaged herbarium specimens become available online, they will play an increasingly critical role in revealing large-scale patterns within assemblages and across continents that ultimately can improve forecasts of the impacts of climatic change on the structure and function of ecosystems.This article is part of the theme issue 'Biological collections for understanding biodiversity in the Anthropocene'.

Impact of Climate Change on Pollen and Respiratory Disease

PURPOSE OF REVIEW

A warming world will impact everyone and everything. The practice of allergic and respiratory disease will not be excepted. All the impacts will be impossible to anticipate. This review is intended to discuss significant factors related to individuals with allergic and respiratory disease.

RECENT FINDINGS

Recent findings include the increased growth of allergenic plants in response to higher carbon dioxide levels and warmer temperatures. This also contributes to the increased production of pollen as well as the appearance of allergenic species in new climactic areas. Stinging insects will extend their ranges into northern areas where they have not previously been a problem. The shift and extension of pollen seasons with warmer springs and later frosts have already been observed. Recent severe hurricanes and flooding events may be just the harbinger of increasing damp housing exposure related to sea level rise. Evidence is accumulating that indicates the expected higher number of ozone alert days and increased pollution in populated areas is bringing increases in pollen potency. Finally, increased exposure to smoke and particles from wild fires, resulting from heat waves, will contribute to the general increase in respiratory disease. The practice of allergy being closely aligned with environmental conditions will be especially impacted. Allergists should consider increasing educational activities aimed at making patients more aware of air quality conditions.

Shifts in pollen release envelope differ between genera with non-uniform climate change

PREMISE OF THE STUDY

Plant phenological responses to climate change now constitute one of the best studied areas of the ecological impacts of climate change. Flowering time responses to climate change of wind-pollinated species have, however, been less well studied. A novel source of flowering time data for wind-pollinated species is allergen monitoring records.

METHODS

We studied the male flowering time response to climatic variables of two wind-pollinated genera, Betula (Betulaceae) and Populus (Salicaceae), using pollen count records over a 17-year period.

KEY RESULTS

We found that changes in the pollen release envelope differed between the two genera. Over the study period, the only month with a significant rise in temperature was April, resulting in the duration of pollen release of the April-flowering Populus to shorten and the start and peak of the May-flowering Betula to advance. The quantity of pollen released by Betula has increased and was related to increases in the previous year's August precipitation, while the quantity of pollen released by Populus has not changed and was related to the previous year's summer and autumn temperatures.

CONCLUSIONS

Our findings suggest that taxa differ in the reproductive consequences of environmental change. Differing shifts in phenology among species may be related to different rates of change in climatic variables in different months of the year. While our study only considers two genera, the results underscore the importance of understanding non-uniform intra-annual variation in climate when studying the ecological implications of climate change.

Does the increase in ambient CO2 concentration elevate allergy risks posed by oak pollen?

Oak pollen is a major respiratory allergen in Korea, and the distribution of oak trees is expected to increase by ecological succession and climate change. One of the drivers of climate change is increasing CO₂, which is also known to amplify the allergy risk of weed pollen by inducing elevated allergenic protein content. However, the impact of CO₂ concentration on tree pollen is not clearly understood due to the experimental difficulties in carrying out extended CO₂ treatment. To study the response of pollen production of sawtooth oak trees (Quercus acutissima) to elevated levels of ambient CO₂, three open-top chambers at the National Institute of Forest Science in Suwon, Korea were utilized with daytime (8 am-6 pm) CO₂ concentrations of ambient (× 1.0, ~ 400 ppm), × 1.4 (~ 560 ppm), and × 1.8 (~ 720 ppm) treatments. Each chamber had three sawtooth oak trees planted in September 2009. One or two trees per chamber matured to bloom in 2016. Five to six catkins were selected per tree and polyethylene bags were attached to collect pollen grains. The total number of catkins per tree was counted and the number and weight of pollen grains per catkin were measured. Oak allergen-Que a 1 (Allergon Co., Uppsala, Sweden)-was extracted and purified to make an ELISA kit by which the antigen levels in the pollen samples were quantified. Total pollen counts per tree of the × 1.4 and × 1.8 treatments showed significant increase of 353 and 1299%, respectively, from the × 1.0 treatment (p < 0.001). Allergenic protein contents at the × 1.4 and × 1.8 treatments also showed significant increase of 12 and 11%, respectively (p = 0.011). The × 1.8 treatment induced significant difference from the × 1.0 treatment in terms of pollen production and allergenic protein content, whereas the × 1.4 treatment showed mixed significance. In summary, the oak trees under the elevated CO₂ levels, which are expected in the changing climate, produced significantly higher amount of pollen and allergenic protein than under the present air conditions.

Prevalence of pollen-induced allergic rhinitis with high pollen exposure in grasslands of northern China

BACKGROUND

The aim of this study was to investigate the prevalence of epidemiologic and physician-diagnosed pollen-induced AR (PiAR) in the grasslands of northern China and to study the impact of the intensity and time of pollen exposure on PiAR prevalence.

METHODS

A multistage, clustered and proportionately stratified random sampling with a field interviewer-administered survey study was performed together with skin prick tests (SPT) and measurements of the daily pollen count.

RESULTS

A total of 6043 subjects completed the study, with a proportion of 32.4% epidemiologic AR and 18.5% PiAR. The prevalence was higher in males than females (19.6% vs 17.4%, P = .024), but no difference between the two major residential and ethnic groups (Han and Mongolian) was observed. Subjects from urban areas showed higher prevalence of PiAR than rural areas (23.1% vs 14.0%, P < .001). Most PiAR patients were sensitized to two or more pollens (79.4%) with artemisia, chenopodium, and humulus scandens being the most common pollen types, which were similarly found as the top three sensitizing pollen allergens by SPT. There were significant regional differences in the prevalence of epidemiologic AR (from 18.6% to 52.9%) and PiAR (from 10.5% to 31.4%) among the six areas investigated. PiAR symptoms were positively associated with pollen counts, temperature, and precipitation (P < .05), but negatively with wind speed and pressure P < .05).

CONCLUSION

Pollen-induced AR (PiAR) prevalence in the investigated region is extremely high due to high seasonal pollen exposure, which was influenced by local environmental and climate conditions.

A statistical model for predicting the inter-annual variability of birch pollen abundance in Northern and North-Eastern Europe

The paper suggests a methodology for predicting next-year seasonal pollen index (SPI, a sum of daily-mean pollen concentrations) over large regions and demonstrates its performance for birch in Northern and North-Eastern Europe. A statistical model is constructed using meteorological, geophysical and biological characteristics of the previous year). A cluster analysis of multi-annual data of European Aeroallergen Network (EAN) revealed several large regions in Europe, where the observed SPI exhibits similar patterns of the multi-annual variability. We built the model for the northern cluster of stations, which covers Finland, Sweden, Baltic States, part of Belarus, and, probably, Russia and Norway, where the lack of data did not allow for conclusive analysis. The constructed model was capable of predicting the SPI with correlation coefficient reaching up to 0.9 for some stations, odds ratio is infinitely high for 50% of sites inside the region and the fraction of prediction falling within factor of 2 from observations, stays within 40-70%. In particular, model successfully reproduced both the bi-annual cycle of the SPI and years when this cycle breaks down.

Pollen-food allergy syndrome is a common allergic comorbidity in adults with eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is associated with atopic diseases including asthma, allergic rhinitis, and atopic dermatitis; however, limited data exist on the correlation between pollen-food allergy syndrome (PFAS) and EoE. We analyzed 346 adults with EoE treated at a single center between 2002 and 2016. Demographic and EoE-specific data including clinical features and measures of EoE disease severity and treatments were collected. The presence of other atopic diseases, family history, prevalence of peripheral eosinophilia and elevated IgE, and details of PFAS triggers were collected. Twenty six percent of the 346 subjects in our cohort had both EoE and PFAS (EoE-PFAS). Compared to subjects with EoE alone, subjects with EoE-PFAS had an increased frequency of allergic rhinitis (86.7% vs. 64.2%, P < 0.001) and family history of allergies (71.1% vs. 53.3%, P = 0.003), and comprised a higher proportion of EoE diagnoses made in the spring (Χ2 < 0.001). 43.3% of subjects with concurrent EoE and PFAS opted for treatment with elimination diet, and these measures failed to induce remission in 46.2% of cases. In most cases, elimination diet failed despite strict avoidance of PFAS trigger foods in addition to common EoE triggers including dairy, wheat, and eggs. EoE-PFAS was also associated with higher serum IgE at the time of EoE diagnosis (460.6 vs. 289.9, P < 0.019). Allergic rhinitis and a family history of food allergy were independently associated with having EoE-PFAS. The most common triggers of PFAS in adults with EoE are apples (21.1%), carrots (15.5%), and peaches (15.5%). Along with asthma, allergic rhinitis and atopic dermatitis, PFAS is a common allergic comorbidity that is highly associated with EoE. Further studies aimed at understanding mechanistic similarities and differences of PFAS and EoE may shed light on the pathogenesis of these closely related food allergy syndromes.

Poaceae pollen as the leading aeroallergen worldwide: A review

The Poaceae family comprises over 12 000 wind-pollinated species, which release large amounts of pollen into the atmosphere. Poaceae pollen is currently regarded as the leading airborne biological pollutant and the chief cause of pollen allergy worldwide. Sensitization rates vary by country, and those variations are reviewed here. Grass pollen allergens are grouped according to their protein structure and function. In Poaceae, although species belonging to different subfamilies are characterized by distinct allergen subsets, there is a considerable degree of cross-reactivity between many species. Cross-reactivity between grass pollen protein and fresh fruit pan-allergens is associated with the appearance of food allergies. The additional influence of urban pollution may prompt a more severe immunological response. The timing and the intensity of the pollen season are governed by species genetics, but plant phenology is also influenced by climate; as a result, climate changes may affect airborne pollen concentrations. This article reviews the findings of worldwide research which has highlighted the major impact of climate change on plant phenology and also on the prevalence and severity of allergic disease.

Impacts of oak pollen on allergic asthma in the United States and potential influence of future climate change

Future climate change is expected to lengthen and intensify pollen seasons in the U.S., potentially increasing incidence of allergic asthma. We developed a proof-of-concept approach for estimating asthma emergency department (ED) visits in the U.S. associated with present-day and climate-induced changes in oak pollen. We estimated oak pollen season length for moderate (Representative Concentration Pathway (RCP) 4.5) and severe climate change scenarios (RCP8.5) through 2090 using five climate models and published relationships between temperature, precipitation, and oak pollen season length. We calculated asthma ED visit counts associated with 1994-2010 average oak pollen concentrations and simulated future oak pollen season length changes using the Environmental Benefits Mapping and Analysis Program, driven by epidemiologically derived concentration-response relationships. Oak pollen was associated with 21,200 (95% confidence interval, 10,000-35,200) asthma ED visits in the Northeast, Southeast, and Midwest U.S. in 2010, with damages valued at $10.4 million. Nearly 70% of these occurred among children age <18 years. Severe climate change could increase oak pollen season length and associated asthma ED visits by 5% and 10% on average in 2050 and 2090, with a marginal net present value through 2090 of $10.4 million (additional to the baseline value of $346.2 million). Moderate versus severe climate change could avoid >50% of the additional oak pollen-related asthma ED visits in 2090. Despite several key uncertainties and limitations, these results suggest that aeroallergens pose a substantial U.S. public health burden, that climate change could increase U.S. allergic disease incidence, and that mitigating climate change may have benefits from avoided pollen-related health impacts.

Climate change: consequences on the pollination of grasses in Perugia (Central Italy). A 33-year-long study

Many works carried out in the last decades have shown that the pollen season for taxa flowering in winter and spring, in temperate regions, has tended to be earlier, probably due to the continuous rise in temperature. The mean annual temperature in Perugia, Central Italy, was about 0.5 °C higher in the last three decades compared with that registered from 1952 to 1981. The increase of temperature took place mainly in winter and spring, while no significant variation was recorded during the summer and autumn. This scenario shows variations in the timing and behavior of flowering of many spontaneous plants such as grasses, whose phenology is strongly influenced by air temperature. This work reports fluctuations in the airborne grass pollen presence in Perugia over a 33-year period (1982-2014), in order to study the influence of the warming registered in recent years on the behavior of pollen release of this taxon. The grass pollen season in Perugia typically lasts from the beginning of May to late July. The start dates showed a marked trend to an earlier beginning of the season (-0.4 day/year), as well as a strong correlation with the average temperatures of March and April. The peak is reached around 30th May, but the annual pollen index (API) is following a decreasing trend. The correlation between starting dates and spring temperatures could be interesting for the constitution of a forecasting model capable of predicting the presence of airborne grass pollen, helping to plan therapies for allergic people.

Pollen Season Trends (1973-2013) in Stockholm Area, Sweden

In the present study, the phenological and quantitative changes in the pollen seasons between 1973 and 2013 in the Stockholm region of Sweden were studied for nine types of pollen (hazel, alder, elm, birch, oak, grass, mugwort, willow and pine). Linear regression models were used to estimate the long term trends in duration, start- and end-dates, peak-values and the yearly accumulated pollen sums of the pollen seasons. The pollen seasons of several arboreal plant species (e.g. birch, oak and pine) were found to start significantly earlier today compared to 41 years earlier, and have an earlier peak-date, while the season of other species seemed largely unaffected. However, the long term trends in the end-dates of pollen seasons differed between arboreal and herbaceous species. For herbaceous species (grass and mugwort), a significant change towards later end-dates was observed and the duration of season was found to have increased. A significant trend towards an earlier end-date was found in the majority of the arboreal plant species (i.e. elm, oak, pine and birch), but the length of the season seemed unaffected. A trend towards an increase in yearly concentrations of pollen was observed for several species; however the reasons for this phenomenon cannot be explained unambiguously by the present study design. The trend of increasing yearly mean air temperatures in the Stockholm area may be the reason to changed phenological patterns of pollen seasons.

Cross-sensitization profiles of edible nuts in a birch-endemic area

BACKGROUND

Sensitization to birch pollen causes cross-sensitization to nuts, but rarely leads to clinical nut allergy. The aim was to study sensitizations to nuts in individuals sensitized to birch pollen and examine cross-reactivities between birch and nut species.

METHODS

All subjects with skin prick tests (SPTs) for birch pollen conducted during 1997-2013 in the Skin and Allergy Hospital in Helsinki (n = 114 572) and their available SPTs for nuts (n = 50 604) were included. Nut sensitizations were analyzed both with and without cosensitization to birch and stratified into age-categories. Cross-reactivities were analyzed with hierarchical clustering. One group of 1589 patients was surveyed for symptoms. Data were gathered also from Lapland to examine sensitizations in an area with less birch-pollen exposure.

RESULTS

Of subjects with birch sensitization, 84% were cosensitized to hazelnut, 71% to almond, and 60% to peanut. In a subgroup without birch sensitization, young children (<5 years) were most commonly nut-sensitized (8-40%); and this prevalence decreased in adolescents and further in adults (4-12%). Cashew and pistachio (ρ = 0.66; P < 0.001) and pecan and walnut (ρ = 0.65; P < 0.001) correlated the strongest. The majority of nut-sensitized patients (71% hazelnut, 83% almond, 73% peanut) reported no or mild symptoms. Cosensitizations between nuts and birch were similar in Lapland with its lower birch-pollen exposure.

CONCLUSION

Birch-sensitized individuals are frequently cosensitized to hazelnut, almond, and peanut. Among the birch-negatives, prevalences of nut sensitizations decrease from early childhood to adolescence. Cashew and pistachio, and pecan and walnut cross-react the most.

Disentangling the effects of feedback structure and climate on Poaceae annual airborne pollen fluctuations and the possible consequences of climate change

Pollen allergies are the most common form of respiratory allergic disease in Europe. Most studies have emphasized the role of environmental processes, as the drivers of airborne pollen fluctuations, implicitly considering pollen production as a random walk. This work shows that internal self-regulating processes of the plants (negative feedback) should be included in pollen dynamic systems in order to give a better explanation of the observed pollen temporal patterns. This article proposes a novel methodological approach based on dynamic systems to investigate the interaction between feedback structure of plant populations and climate in shaping long-term airborne Poaceae pollen fluctuations and to quantify the effects of climate change on future airborne pollen concentrations. Long-term historical airborne Poaceae pollen data (30 years) from Cordoba city (Southern Spain) were analyzed. A set of models, combining feedback structure, temperature and actual evapotranspiration effects on airborne Poaceae pollen were built and compared, using a model selection approach. Our results highlight the importance of first-order negative feedback and mean annual maximum temperature in driving airborne Poaceae pollen dynamics. The best model was used to predict the effects of climate change under two standardized scenarios representing contrasting temporal patterns of economic development and CO2 emissions. Our results predict an increase in pollen levels in southern Spain by 2070 ranging from 28.5% to 44.3%. The findings from this study provide a greater understanding of airborne pollen dynamics and how climate change might impact the future evolution of airborne Poaceae pollen concentrations and thus the future evolution of related pollen allergies.

The associations between daily spring pollen counts, over-the-counter allergy medication sales, and asthma syndrome emergency department visits in New York City, 2002-2012

BACKGROUND

Many types of tree pollen trigger seasonal allergic illness, but their population-level impacts on allergy and asthma morbidity are not well established, likely due to the paucity of long records of daily pollen data that allow analysis of multi-day effects. Our objective in this study was therefore to determine the impacts of individual spring tree pollen types on over-the-counter allergy medication sales and asthma emergency department (ED) visits.

METHODS

Nine clinically-relevant spring tree pollen genera (elm, poplar, maple, birch, beech, ash, sycamore/London planetree, oak, and hickory) measured in Armonk, NY, were analyzed for their associations with over-the-counter allergy medication sales and daily asthma syndrome ED visits from patients' chief complaints or diagnosis codes in New York City during March 1st through June 10th, 2002-2012. Multi-day impacts of pollen on the outcomes (0-3 days and 0-7 days for the medication sales and ED visits, respectively) were estimated using a distributed lag Poisson time-series model adjusting for temporal trends, day-of-week, weather, and air pollution. For asthma syndrome ED visits, age groups were also analyzed. Year-to-year variation in the average peak dates and the 10th-to-90th percentile duration between pollen and the outcomes were also examined with Spearman's rank correlation.

RESULTS

Mid-spring pollen types (maple, birch, beech, ash, oak, and sycamore/London planetree) showed the strongest significant associations with both outcomes, with cumulative rate ratios up to 2.0 per 0-to-98th percentile pollen increase (e.g., 1.9 [95% CI: 1.7, 2.1] and 1.7 [95% CI: 1.5, 1.9] for the medication sales and ED visits, respectively, for ash). Lagged associations were longer for asthma syndrome ED visits than for the medication sales. Associations were strongest in children (ages 5-17; e.g., a cumulative rate ratio of 2.6 [95% CI: 2.1, 3.1] per 0-to-98th percentile increase in ash). The average peak dates and durations of some of these mid-spring pollen types were also associated with those of the outcomes.

CONCLUSIONS

Tree pollen peaking in mid-spring exhibit substantive impacts on allergy, and asthma exacerbations, particularly in children. Given the narrow time window of these pollen peak occurrences, public health and clinical approaches to anticipate and reduce allergy/asthma exacerbation should be developed.

Predicting Onset and Duration of Airborne Allergenic Pollen Season in the United States

Allergenic pollen is one of the main triggers of Allergic Airway Disease (AAD) affecting 5% to 30% of the population in industrialized countries. A modeling framework has been developed using correlation and collinearity analyses, simulated annealing, and stepwise regression based on nationwide observations of airborne pollen counts and climatic factors to predict the onsets and durations of allergenic pollen seasons of representative trees, weeds and grass in the contiguous United States. Main factors considered are monthly, seasonal and annual mean temperatures and accumulative precipitations, latitude, elevation, Growing Degree Day (GDD), Frost Free Day (FFD), Start Date (SD) and Season Length (SL) in the previous year. The estimated mean SD and SL for birch (Betula), oak (Quercus), ragweed (Ambrosia), mugwort (Artemisia) and grass (Poaceae) pollen season in 1994-2010 are mostly within 0 to 6 days of the corresponding observations for the majority of the National Allergy Bureau (NAB) monitoring stations across the contiguous US. The simulated spatially resolved maps for onset and duration of allergenic pollen season in the contiguous US are consistent with the long term observations.