Do levels of airborne grass pollen influence asthma hospital admissions?

Association of asthma exacerbations with paper mulberry (Broussenetia papyrifera) pollen in Islamabad: An observational study

Background

Although the role of airborne plant pollen in causing allergic rhinitis has been established, the association of concentrations of paper mulberry (Broussenetia papyrifera) pollens in the air and incidence of asthma exacerbations has not, despite an observed increase in the number of asthma patients attending physician clinics and hospital Accident and Emergency (A&E) Departments during the paper mulberry pollen season. We aimed to assess the association between paper mulberry pollen concentrations (typically peaking in March each year) and asthma exacerbations in the city of Islamabad.

Methods

We used three approaches to investigate the correlation of paper mulberry pollen concentration with asthma exacerbations: A retrospective analysis of historical records (2000-2019) of asthma exacerbations of patients from the Allergy and Asthma Institute, Pakistan (n = 284), an analysis of daily nebulisations in patients attending the A&E Department of the Pakistan Institute of Medical Sciences (March 2020 to July 2021), a prospective peak expiratory flow rate (PEFR) diary from participants (n = 40) with or without asthma and with or without paper mulberry sensitisation. We examined associations between pollen data and asthma exacerbations using Pearson correlation.

Results

We found a strong positive correlation between mean paper mulberry pollen counts and clinical records of asthma exacerbations in patients sensitised to paper mulberry (Pearson correlation coefficient (r) = 0.86; P < 0.001), but not in non-sensitised patients (r = 0.32; P = 0.3). There was a moderate positive correlation between monthly nebulisation counts and pollen counts (r = 0.56; P = 0.03), and a strong negative correlation between percent predicted PEFR and pollen counts in sensitised asthma patients (r = -0.72, P < 0.001). However, these correlations were of low magnitude in the non-sensitised asthma (r = -0.16; P < 0.001) and sensitised non-asthma (r = -0.28; P < 0.001) groups.

Conclusions

Our three approaches to analysis all showed an association between high paper mulberry pollen concentration in Islamabad and asthma exacerbations. Predicting pollen peaks could enable alerts and mobilise strategies to proactively manage these peaks of asthma exacerbations.

Association between grass, tree and weed pollen and asthma health outcomes in Adelaide, South Australia: a time series regression analysis

OBJECTIVES

We aim to establish daily risk estimates of the relationships between grass, tree and weed pollen and asthma health outcomes.

DESIGN

Time series regression analysis of exposure and health outcomes using interaction by month to determine risk estimates all year round.

SETTING

Metropolitan Adelaide, South Australia.

PARTICIPANTS

Health outcomes for asthma are based on 15 years of hospital admissions, 13 years emergency presentations and ambulance callouts. In adults (≥18 years), there were 10 381 hospitalisations, 26 098 emergency department (ED) presentations and 11 799 ambulance callouts and in children (0-17 years), 22 114, 39 813 and 3774, respectively.

OUTCOME MEASURES

The cumulative effect of 7 day lags was calculated as the sum of the coefficients and reported as incidence rate ratio (IRR) related to an increase in 10 grains of pollen/m³.

RESULTS

In relation to grass pollen, children and adults were disparate in their timing of health effects. Asthma outcomes in children were positively related to grass pollen in May, and for adults in October. Positive associations with weed pollen in children was seen from February to May across all health outcomes. For adults, weed pollen-related health outcomes were restricted to February. Adults were not affected by tree pollen, while children's asthma morbidity was associated with tree pollen in August and September. In children, IRRs ranged from 1.14 (95% CI 1.06 to 1.21) for ED presentations for tree pollen in August to 1.98 (95% CI 1.06 to 3.72) for weed pollen in February. In adults, IRRs ranged from 1.28 (95% CI 1.01 to 1.62) for weed pollen in February to 1.31 (95% CI 1.08 to 1.57) for grass pollen in October.

CONCLUSION

Monthly risk assessment indicated that most pollen-related asthma health outcomes in children occur in the colder part of the year, while adults are affected in the warm season. The findings indicate a need for year-round pollen monitoring and related health campaigns to provide effective public health prevention.

Asthma Hospital Admission and Readmission Spikes, Advancing Accurate Classification to Advance Understanding of Causes

BACKGROUND

An important component of asthma care is understanding potential causes of high asthma admissions (HAADs) or readmissions (HARDs) with potential of risk mitigation. Crucial to this research is accurately distinguishing these events from background seasonal changes and time trends. To date, classification methods have been based on ad hoc and untested definitions which may hamper understanding causes of HAADs and HARDs due to misclassification. The aim of this article is to introduce an easily applied robust statistical approach, with high classification accuracy in other settings-the Seasonal Hybrid Extreme Studentized Deviate (S-H-ESD) method.

METHODS

We demonstrate S-H-ESD on a time series between 1996 and 2009 of all daily paediatric asthma hospital admissions in Victoria, Australia.

RESULTS

S-H-ESD clearly identified HAADs and HARDs without applying ad hoc classification definitions, while appropriately accounting for seasonality and time trend. Importantly, it was done with statistical testing, providing evidence in support of their identification.

CONCLUSION

S-H-ESD is useful and statistically appropriate for accurate classification of HAADs and HARDS. It obviates ad hoc approaches and presents as a means of systemizing their accurate classification and detection. This will strengthen synthesis and efficacy of research toward understanding causes of HAADs and HARDs for their risk mitigation.

The role of short-term grass pollen exposure in food skin-prick test reactivity, food allergy, and eczema flares in children

BACKGROUND

While the relationship between pollen and respiratory allergies is well-documented, the role of short-term pollen exposure in food allergy and eczema flares has not previously been explored. We aimed to investigate these associations in a population-based sample of children.

METHODS

We investigated 1- (n = 1108) and 6-year-old (n = 675) children in the grass pollen season from the HealthNuts cohort. Grass pollen concentrations were considered on the day of testing (lag 0), up to three days before (lag 1-lag 3) and cumulatively (lag 0-3). Associations between grass pollen and food skin-prick test reactivity (SPT ≥ 2 mm at age 1 year and ≥ 3 mm at age 6 years), eczema flares, challenge-confirmed food allergy, reaction threshold to oral food challenges (OFC), and serum food-specific IgE levels were analyzed using either logistic or quantile regression models. Atopy and family history of allergic disease were considered as potent effect modifiers.

RESULTS

Grass pollen at lag 0-3 (every 20 grains/m³ increase) was associated with an up to 1.2-fold increased odds of food SPT reactivity and eczema flares in 6-year-olds. In 1-year-olds, the associations were only observed for peanut in those with a family history of food allergy. Increasing grass pollen concentrations were associated with a lower reaction threshold to OFC and higher serum IgE levels in peanut-allergic 1-year-olds only.

CONCLUSION

Increasing grass pollen concentration was associated with increased risk of food SPT reactivity and eczema flares in children. The associations in peanut-allergic infants may be related to immune activation and/or peanut and grass pollen cross-reactivity leading to a lower reaction threshold.

Temporal Changes in Pollen Concentration Predict Short-Term Clinical Outcomes in Acute Coronary Syndromes

Background Atmospheric changes in pollen concentration may affect human health by triggering various allergic processes. We sought to assess if changes in pollen concentrations were associated with different acute coronary syndrome (ACS) subtype presentations and short-term clinical outcomes. Methods and Results We analyzed data in consecutive patients presenting with ACS (unstable angina, non-ST-segment-elevation myocardial infarction, and ST-segment-elevation myocardial infarction) treated with percutaneous coronary intervention between January 2014 and December 2017 and enrolled in the VCOR (Victorian Cardiac Outcomes Registry). Baseline characteristics were compared among patients exposed to different grass and total pollen concentrations. The primary outcome was occurrence of ACS subtypes and 30-day major adverse cardiac and cerebrovascular events (composite of mortality, myocardial infarction, stent thrombosis, target vessel revascularization, or stroke). Of 15 379 patients, 7122 (46.3%) presented with ST-segment-elevation myocardial infarction, 6781 (44.1%) with non-ST-segment-elevation myocardial infarction, and 1476 (9.6%) with unstable angina. The mean age was 62.5 years, with men comprising 76% of patients. No association was observed between daily or seasonal grass and total pollen concentrations with the frequency of ACS subtype presentation. However, grass and total pollen concentrations in the preceding days (2-day average for grass pollen and 7-day average for total pollen) correlated with in-hospital mortality (odds ratio [OR], 2.17 [95% CI, 1.12-4.21]; P=0.021 and OR, 2.78 [95% CI, 1.00-7.74]; P=0.05), respectively, with a trend of 2-day grass pollen for 30-day major adverse cardiac and cerebrovascular events (OR, 1.50 [95% CI, 0.97-2.32]; P=0.066). Conclusions Increased pollen concentrations were not associated with differential ACS subtype presentation but were significantly related to in-hospital mortality following percutaneous coronary intervention, underscoring a potential biologic link between pollen exposure and clinical outcomes.

Exposome mapping in chronic respiratory diseases: the added value of digital technology

PURPOSE OF REVIEW

The development and progression of chronic respiratory diseases are impacted by a complex interplay between genetic, microbial, and environmental factors. Here we specifically summarize the effects of environmental exposure on asthma, allergic rhinitis, and chronic rhinosinusitis. We furthermore discuss how digital health technology may aid in the assessment of the environmental exposure of patients and how it may be of added value for them.

RECENT FINDINGS

It is well established that one gets allergic symptoms if sensitized and exposed to the same allergen. Viruses, bacteria, pollutants, irritants, and lifestyle-related factors modify the risk of getting sensitized and develop symptoms or may induce symptoms themselves. Understanding these processes and how the various factors interact with each other and the human body require big data and advanced statistics. Mobile health technology enables integration of multiple sources of data of the patients' exposome and link these to patient outcomes. Such technologies may contribute to the increased understanding of the development of chronic respiratory disease.

SUMMARY

Implementation of digital technologies in clinical practice may in future guide the development of preventive strategies to tackle chronic respiratory diseases and eventually improve outcomes of the patient.

Family, neighborhood and psychosocial environmental factors and their associations with asthma in Australia: a systematic review and Meta-analysis

OBJECTIVE

Various associations between different environmental exposures and asthma have been reported in different countries and populations. We aimed to investigate the associations between family, neighborhood and psychosocial environmental factors and asthma-symptoms in Australia by conducting a systematic review and meta-analysis.

DATA SOURCES

We analyzed the primary research studies conducted in Australia across multiple databases, including PubMed, EMBASE and Scopus, published between 2000 and 2020.

STUDY SELECTIONS

The reviews and analyses focused on the overall association of different environmental exposures with the exacerbation of asthma-symptoms or asthma-related hospital visits. Quality-effect meta-analysis was done to estimate the pooled odds ratio for different environmental exposures for asthma-symptoms.

RESULTS

Among the 4799 unique published articles found, 46 were included here for systematic review and 28 for meta-analysis. Our review found that psychosocial factors, including low socioeconomic condition, maternal depression, mental stress, ethnicity, and discrimination, are associated with asthma-symptoms. Pooled analysis was conducted on family and neighborhood environmental factors and revealed that environmental tobacco smoking (ETS) (OR 1·69, 95% CI 1·19-2·38), synthetic bedding (OR 1·91, 95% CI 1·48-2·47) and gas heaters (OR 1·40, 95% CI 1·12-1·76) had significant overall associations with asthma-symptoms in Australia.

CONCLUSION

Although the studies were heterogeneous, both systematic review and meta-analysis found several psychosocial and family environmental exposures significantly associated with asthma-symptoms. Further study to identify their causal relationship and modification may reduce asthma-symptoms in the Australian population.

Characterising non-linear associations between airborne pollen counts and respiratory symptoms from the AirRater smartphone app in Tasmania, Australia: A case time series approach

Pollen is a well-established trigger of asthma and allergic rhinitis, yet concentration-response relationships, lagged effects, and interactions with other environmental factors remain poorly understood. Smartphone technology offers an opportunity to address these challenges using large, multi-year datasets that capture individual symptoms and exposures in real time. We aimed to characterise associations between six pollen types and respiratory symptoms logged by users of the AirRater smartphone app in Tasmania, Australia. We analyzed 44,820 symptom reports logged by 2272 AirRater app users in Tasmania over four years (2015-2019). With these data we evaluated associations between daily respiratory symptoms and atmospheric pollen concentrations. We implemented Poisson regression models, using the case time series approach designed for app-sourced data. We assessed potentially non-linear and lagged associations with (a) total pollen and (b) six individual pollen taxa. We adjusted for seasonality and meteorology and tested for interactions with particulate air pollution (PM_2.5). We found evidence of non-linear associations between total pollen and respiratory symptoms for up to three days following exposure. For total pollen, the same-day relative risk (RR) increased to 1.31 (95% CI: 1.26-1.37) at a concentration of 50 grains/m³ before plateauing. Associations with individual pollen taxa were also non-linear with some diversity in shapes. For all pollen taxa the same-day RR was highest. The interaction between total pollen and PM_2.5 was positive, with risks associated with pollen significantly higher in the presence of high concentrations of PM_2.5. Our results support a non-linear response between airborne pollen and respiratory symptoms. The association was strongest on the day of exposure and synergistic with particulate air pollution. The associations found with Dodonaea and Myrtaceae highlight the need to further investigate the role of Australian native pollen types in allergic respiratory disease.

Pollen forecasting and its relevance in pollen allergen avoidance

Pollinosis and allergic asthma are respiratory diseases of global relevance, heavily affecting the quality of life of allergic subjects. Since there is not a decisive cure yet, pollen allergic subjects need to avoid exposure to high pollen allergens concentrations. For this purpose, pollen forecasting is an essential tool that needs to be reliable and easily accessible. While forecasting methods are rapidly evolving towards more complex statistical and physical models, the use of simple and traditional methods is still preferred in routine predictions. In this review, we summarise and explain the main parameters considered when forecasting pollen, and classify the different forecasting methods in two groups: observation-based and process-based. Finally, we compare these approaches based on their usefulness to allergic patients, and discuss possible future developments of the field.

Prevalence and risk factors of allergic rhinitis and asthma in the southern edge of the plateau grassland region of northern China: A cross-sectional study

Background

The prevalence rates of allergic rhinitis (AR) and asthma in the border region of China may be different from those in the central region of plateau grasslands. A survey was performed to investigate the prevalence and risk factors for AR, asthma, and AR combined with asthma among adults (age ≥ 20 years) residing in the southern border of plateau grasslands in northern China.

Methods

From May to August 2018, a cross-sectional survey was completed by subjects that were selected using a cluster random sampling method. The subjects completed a questionnaire and were administered skin prick tests (SPTs). Risk factors for AR, asthma, and AR combined with asthma were examined by multivariate logistic regression analyses.

Results

A total of 1815 adult subjects in the selected region completed study. The prevalence rates of physician-diagnosed AR, asthma, and AR combined with asthma were 13.9% (253), 9.8% (177), and 2.9% (52), respectively. Among the patients with AR, 20.6% were found to have concurrent asthma; among the patients with asthma, 29.4% were found to have concurrent AR. Artemisia and Humulus pollen were the most common sensitizing pollen types. Approximately 70% of subjects with AR and <30% of asthma patients were sensitized to Artemisia and Humulus pollen. Symptoms of AR and asthma mainly appeared during August. A multivariable logistic regression analysis identified sensitization pollen as an independent risk factor for both AR and AR combined with asthma (AR: OR = 16.23, 95% CI: 10.15–25.96; AR combined with asthma: OR = 6.16, 95% CI: 1.28–29.66). An age >40 years old, family history of asthma, moderate-to-severe AR, adverse food reactions, and mold allergies were independent risk factors for AR combined with asthma.

Conclusions

This study identified the prevalence rates of AR and asthma in the southern borders of the plateau grassland in northern China (>1500 m above sea level). Sensitization pollen is an independent risk factor for AR and AR combined with asthma.

Anthropogenic climate change is worsening North American pollen seasons

Human-caused climate change could impact respiratory health, including asthma and allergies, through temperature-driven increases in airborne pollen, but the long-term continental pollen trends and role of climate change in pollen patterns are not well-understood. We measure pollen trends across North America from 1990 to 2018 and find increases in pollen concentrations and longer pollen seasons. We use an ensemble of climate models to test the role of climate change and find that it is the dominant driver of changes in pollen season length and a significant contributor to increasing pollen concentrations. Our results indicate that human-caused climate change has already worsened North American pollen seasons, and climate-driven pollen trends are likely to further exacerbate respiratory health impacts in coming decades.

Airborne pollen has major respiratory health impacts and anthropogenic climate change may increase pollen concentrations and extend pollen seasons. While greenhouse and field studies indicate that pollen concentrations are correlated with temperature, a formal detection and attribution of the role of anthropogenic climate change in continental pollen seasons is urgently needed. Here, we use long-term pollen data from 60 North American stations from 1990 to 2018, spanning 821 site-years of data, and Earth system model simulations to quantify the role of human-caused climate change in continental patterns in pollen concentrations. We find widespread advances and lengthening of pollen seasons (+20 d) and increases in pollen concentrations (+21%) across North America, which are strongly coupled to observed warming. Human forcing of the climate system contributed ∼50% (interquartile range: 19–84%) of the trend in pollen seasons and ∼8% (4–14%) of the trend in pollen concentrations. Our results reveal that anthropogenic climate change has already exacerbated pollen seasons in the past three decades with attendant deleterious effects on respiratory health.

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.

Satellite Monitoring for Air Quality and Health

Data from satellite instruments provide estimates of gas and particle levels relevant to human health, even pollutants invisible to the human eye. However, the successful interpretation of satellite data requires an understanding of how satellites relate to other data sources, as well as factors affecting their application to health challenges. Drawing from the expertise and experience of the 2016-2020 NASA HAQAST (Health and Air Quality Applied Sciences Team), we present a review of satellite data for air quality and health applications. We include a discussion of satellite data for epidemiological studies and health impact assessments, as well as the use of satellite data to evaluate air quality trends, support air quality regulation, characterize smoke from wildfires, and quantify emission sources. The primary advantage of satellite data compared to in situ measurements, e.g., from air quality monitoring stations, is their spatial coverage. Satellite data can reveal where pollution levels are highest around the world, how levels have changed over daily to decadal periods, and where pollutants are transported from urban to global scales. To date, air quality and health applications have primarily utilized satellite observations and satellite-derived products relevant to near-surface particulate matter <2.5 μm in diameter (PM_2.5) and nitrogen dioxide (NO₂). Health and air quality communities have grown increasingly engaged in the use of satellite data, and this trend is expected to continue. From health researchers to air quality managers, and from global applications to community impacts, satellite data are transforming the way air pollution exposure is evaluated.

Is short-term exposure to grass pollen adversely associated with lung function and airway inflammation in the community?

BACKGROUND

The association between grass pollen exposure and early markers of asthma exacerbations such as lung function changes and increase in airway inflammation is limited. We investigated the associations between short-term grass pollen exposure and lung function and airway inflammation in a community-based sample, and whether any such associations were modified by current asthma, current hay fever, pollen sensitization, age, and other environmental factors.

METHODS

Cross-sectional and short-term analyses of data from the Melbourne Atopy Cohort Study (MACS) participants (n = 936). Lung function was assessed using spirometry. Airway inflammation was assessed by fractional exhaled nitric oxide (FeNO) and exhaled breath condensate pH and nitrogen oxides (NOx). Daily pollen counts were collected using a volumetric spore trap. The associations were examined by linear regression.

RESULTS

Higher ambient levels of grass pollen 2 days before (lag 2) were associated with lower mid-forced expiratory flow (FEF_25%-75% ) and FEV₁ /FVC ratio (Coef. [95% CI] = -119 [-226, -11] mL/s and -1.0 [-3.0, -0.03] %, respectively) and also 3 days before (lag 3). Increased levels of grass pollen a day before (lag 1) were associated with increased FeNO (4.35 [-0.1, 8.7] ppb) and also at lag 2. Adverse associations between pollen and multiple outcomes were greater in adults with current asthma, hay fever, and pollen sensitization.

CONCLUSION

Grass pollen exposure was associated with eosinophilic airway inflammation 1-2 days after exposure and airway obstruction 2-3 days after exposure. Adults and individuals with asthma, hay fever, and pollen sensitization may be at higher risk.

Environmental DNA reveals links between abundance and composition of airborne grass pollen and respiratory health

Grass (Poaceae) pollen is the most important outdoor aeroallergen,¹ exacerbating a range of respiratory conditions, including allergic asthma and rhinitis ("hay fever").^2-5 Understanding the relationships between respiratory diseases and airborne grass pollen with a view to improving forecasting has broad public health and socioeconomic relevance. It is estimated that there are over 400 million people with allergic rhinitis⁶ and over 300 million with asthma, globally,⁷ often comorbidly.⁸ In the UK, allergic asthma has an annual cost of around US$ 2.8 billion (2017).⁹ The relative contributions of the >11,000 (worldwide) grass species (C. Osborne et al., 2011, Botany Conference, abstract) to respiratory health have been unresolved,¹⁰ as grass pollen cannot be readily discriminated using standard microscopy.¹¹ Instead, here we used novel environmental DNA (eDNA) sampling and qPCR^12-15 to measure the relative abundances of airborne pollen from common grass species during two grass pollen seasons (2016 and 2017) across the UK. We quantitatively demonstrate discrete spatiotemporal patterns in airborne grass pollen assemblages. Using a series of generalized additive models (GAMs), we explore the relationship between the incidences of airborne pollen and severe asthma exacerbations (sub-weekly) and prescribing rates of drugs for respiratory allergies (monthly). Our results indicate that a subset of grass species may have disproportionate influence on these population-scale respiratory health responses during peak grass pollen concentrations. The work demonstrates the need for sensitive and detailed biomonitoring of harmful aeroallergens in order to investigate and mitigate their impacts on human health.

Outdoor pollen-related changes in lung function and markers of airway inflammation: A systematic review and meta-analysis

BACKGROUND

Experimental challenge studies have shown that pollen can have early and delayed effects on the lungs and airways. Here, we qualitatively and quantitatively synthesize the evidence of outdoor pollen exposure on various lung function and airway inflammation markers in community-based studies.

METHODS

Four online databases were searched: Medline, Web of Science, CINAHL and Google Scholar. The search strategy included terms relating to both exposure and outcomes. Inclusion criteria were human-based studies published in English that were representative of the community. Additionally, we only considered cross-sectional or short-term longitudinal studies which investigated pollen exposure by levels or season. Study quality assessment was performed using the Newcastle-Ottawa scale. Meta-analysis was conducted using random-effects models.

RESULTS

We included 27 of 6551 studies identified from the search. Qualitative synthesis indicated associations between pollen exposure and predominantly type-2 inflammation in both the upper and lower airways, but little evidence for lung function changes. People with ever asthma and/or seasonal allergic rhinitis (SAR) were at higher risk of such airway inflammation. Meta-analysis confirmed a positive relationship between pollen season, eosinophilia and eosinophil cationic protein (ECP) in people with ever SAR but the results between studies were highly variable. Heterogeneity was reduced after further subgrouping by age, and the forest plots indicated that eosinophilic airway inflammation to outdoor pollen exposure increased with age.

CONCLUSION

Among people with ever asthma and ever SAR, exposure to increased ambient pollen triggers type-2 upper and lower airway inflammation rather than a non-specific or innate inflammation. These findings can lead to the formulation of specific pollen immunotherapy for susceptible individuals. Future research should be directed towards investigating lagged associations and effect modifications using larger and more generalized populations.

SYSTEMATIC REVIEW REGISTRATION

CRD42020146981 (PROSPERO).

The Impact of Climate Change on Pollen Season and Allergic Sensitization to Pollens

Pollens are a major cause of seasonal allergic diseases. Weather may alter the production of pollens. Increased atmospheric temperatures lead to earlier pollination of many plants and longer duration of pollination, resulting in extended pollen seasons, with early spring or late winter. Longer pollen seasons increase duration of exposure, resulting in more sensitization, and higher pollen concentrations may lead to more severe symptoms. Climate changes in contact to pollens may affect both allergic sensitization and symptom prevalence with severity. The future consequences of climate change, however, are speculative, because the influence on humans, is complex.

Respiratory illness, hospital visits, and health costs: Is it air pollution or pollen?

BACKGROUND

Both air pollution and airborne pollen can cause respiratory health problems. Since both are often jointly present in ambient air, it is important to control for one while estimating the effect of the other when considering pollution-abating policies. To date only a limited number of studies have considered the health effects of both irritants jointly for a general population, and for a sufficiently long time period to allow for variation in seasonal concentrations of both components. The primary goal of this study is to determine the causal impact of fine particulate matter (PM_2.5) on hospital visits and related treatment costs, while controlling for potentially confounding pollen effects. Our study area is the metropolitan hub of Reno/Sparks in Northern Nevada.

METHODS

Taking advantage of a rare sample of daily pollen counts over a prolonged period of time (2009-2015), we model the effects of PM_2.5 and pollen on respiratory-related hospital admissions for the population at large, plus specific age groups. Pollen data are provided by a local allergy clinic. Data on PM_2.5 and other air pollutants are obtained from the U.S. Environmental Protection Agency's air quality data web site. We collect daily meteorological data from the National Centers for Environmental Information's data repository. Data on hospital admissions are given by the Nevada Center for Surveys, Evaluations, and Statistics. Our econometric approach centers on a fully robust count data (Poisson) model, estimated via Quasi-Maximum Likelihood.

RESULTS

We find that for our sample PM_2.5 effects are largely robust to the inclusion of both pollen counts and temporal indicators. In contrast, pollen effects vanish when time fixed effects are added, pointing at their correlation with unobserved temporal confounders. At the same time, model fit improves with the inclusion of temporal indicators. Based on our preferred specification, we find a significant PM_2.5 effect of approximately 0.5% additional hospital visits per day due to a one μg/m³ increase in PM_2.5. This translates into expected augmented treatment costs of $2700 per day for the same unit-change in PM_2.5. These figures can mount quickly when more pronounced and/or longer episodes of particulate matter pollution are considered, perhaps due to wildfire smoke. For instance, the expected increase in patients and costs due to a month-long 10-unit-jump of PM_2.5 over the long-run annual average would amount to an extra 70 patients and approximately $680,000 in additional treatment costs.

Using crowd-sourced allergic rhinitis symptom data to improve grass pollen forecasts and predict individual symptoms

Seasonal allergic rhinitis (AR), also known as hay fever, is a common respiratory condition brought on by a range of environmental triggers. Previous work has characterised the relationships between community-level AR symptoms collected using mobile apps in two Australian cities, Canberra and Melbourne, and various environmental covariates including pollen. Here, we build on these relationships by assessing the skill of models that provide a next-day forecast of an individual's risk of developing AR and that nowcast ambient grass pollen concentrations using crowd-sourced AR symptoms as a predictor. Categorical grass pollen forecasts (low/moderate/high) were made based on binning mean daily symptom scores by corresponding categories. Models for an individual's risk were constructed by forward variable selection, considering environmental, demographic, behaviour and health-related inputs, with non-linear responses permitted. Proportional-odds logistic regression was then applied with the variables selected, modelling the symptom scores on their original five-point scale. AR symptom-based estimates of today's average grass pollen concentration were more accurate than those provided by two benchmark forecasting methods using various metrics for assessing accuracy. Predictions of an individual's next-day AR symptoms rated on a five-point scale were correct in 36% of cases and within one point on this scale in 82% of cases. Both outcomes were significantly better than chance. This large-scale AR symptoms measurement program shows that crowd-sourced symptom scores can be used to predict the daily average grass pollen concentration, as well as provide a personalised AR forecast.

Crowd-sourced allergic rhinitis symptom data: The influence of environmental and demographic factors

Allergic Rhinitis (AR) affects over half a billion people worldwide with an estimated prevalence of 1 in 5 individuals in developed countries. Although ambient pollen exposure is a causal factor in AR, the symptom-exposure relationship is typically not studied in the broader community but in small, well-characterised cohorts drawn from clinical populations. To identify relationships between AR symptoms in the community and a range of environmental factors, we used a database containing over 96,000 symptom score reports collected over a 3-year period (2014-2016) through freely available smartphone apps released in two Australian cities, Melbourne and Canberra. Ambient pollen levels and symptom scores were strongly related, with grass pollen explaining most of the symptom variation. Other factors correlated with higher symptom scores included temperature (R > 0.73) and wind speed (R > 0.75). In general, worse symptom scores were reported by younger participants, women, and those who had taken medication for AR in the preceding 24 h. The strength of this relationship varied between the two cities. Smartphone-based symptom surveys offer a cost-effective means of studying real-world risk factors for AR in a broader 'extra-clinical' population.

Sensitization to subtropical grass pollens in patients with seasonal allergic rhinitis from Bahia Blanca, Argentina

Background

Grass pollinosis is an important contributor to allergic diseases, with varying patterns and frequency of allergens according to the geographical location studied. Our study aims to provide a better understanding of subtropical grass pollinosis in Argentinian patients with seasonal allergic rhinitis.

Methods

We conducted a retrospective cross-sectional study involving 894 patients with seasonal allergic rhinitis from Bahía Blanca, Argentina. Skin prick tests were performed to selected pollen species belonging to three subfamilies of the Poaceae genera. Frequency of sensitization to specific grass pollen extracts, cross-reactivity of allergens assessed by skin prick test, and possible associations between allergen extracts and asthma or allergic conjunctivitis were analyzed.

Results

Sensitization to the Pooideae subfamily was the most frequent, encompassing 86.8% (CI: 84.4%–88.9%) of the studied population. Positive reactions to allergen extracts from the Chloridoideae and the Panicoideae subfamilies showed smaller papule size than allergen extracts from the Pooideae subfamily (χ²(5) = 83.75, p < 0.001). Patients with a positive skin prick test (SPT) to a specific extract were more likely to present some degree of cross-reactivity to the remaining pollens when compared to patients with negative SPT to the same specific extract. Even though the proportion of patients presenting with asthma (46.9%) was higher than those with conjunctivitis (22.6%), there was only a statistically significant association between sensitization to Festuca arundinacea (φ = 0.089, p = .009), Phalaris arundinacea (φ = 0.074, p = .032) and Paspalum notatum (φ = 0.070, p = .038) and the presence of conjunctivitis.

Conclusions

Our results suggest a high frequency of sensitization to grass pollen extracts from the Poaceae family among patients with seasonal allergic rhinitis. Overall, sensitization to the Pooidae subfamily was the most common, where Phalaris arundinacea presented the highest frequency.

Identification of airborne pollen allergens from two avenue trees of India

An attempt has been made to detect airborne pollen of Lagerstroemia speciosa (LS) and Spathodea campanulata (SC) - two common avenue trees of India as potential sources of aeroallergens and also to identify the major IgE-reactive components present in them. The airborne pollen concentration was assessed using a Burkard sampler. A detailed questionnaire on clinical data of 1490 patients was recorded based on hospital data. We assessed the allergenicity of pollen by in vivo and in vitro tests. The correlation among meteorological factors, pollen seasons and allergenic potency of patients was assessed by multiple regression analysis. The sensitivity of patients to pollen antigens was highly correlated with pollen seasons. In SDS-PAGE, 15 protein bands were detected from LS pollen, while 14 bands from SC. The IgE-specific immunoblotting with patients' sera allergic to LS displayed five major allergens, while four major allergens were detected from SC. This would be the first report from India to prove the allergenic potentiality of airborne pollen of these two common avenue trees of India.

Climate change: allergens and allergic diseases

Climate change has been described as the biggest global health threat of the 21st century. The atmospheric concentrations of greenhouse gases, such as carbon dioxide, methane and nitrous oxide, have increased significantly since the start of the Industrial Era around 1750, with much of this increase occurring over just the last 50 years or so. This is resulting in warming of the climate system as well as changes in precipitation and weather and climate extremes. These changes in climate are having wide-ranging impacts on the Earth's physical, biological and human systems, including human health. It is these impacts of climate change on human health that are the focus of this paper, particularly the impacts on allergens and allergic diseases. Such impacts are particularly significant in many countries where the prevalence of such diseases is high and/or increasing. There is now compelling evidence that rising air temperatures and carbon dioxide concentrations are, in some plant species, resulting in increased pollen production and allergenicity and advancement and lengthening of the pollen season. Changes in extreme events, such as thunderstorms and tropical cyclones, will also have impacts on allergic diseases, with, for example, the flooding associated with tropical cyclones leading to proliferation of mould growth in damp homes. The article also considers a range of responses to these health threats, including greenhouse gas mitigation, and adaptation strategies, such as enhanced environmental monitoring and health surveillance and adequate planning for the future medical workforce.

The association of environmental, meteorological, and pollen count variables with asthma-related emergency department visits and hospitalizations in the Bronx

Objective: To better understand how meteorological variables, air quality variables, and pollen counts collectively contribute to asthma-related emergency department visits (AREDV) and asthma-related hospitalizations (ARH) among pediatric and adult patients in the New York City borough of the Bronx. Methods: The numbers of daily adult and pediatric AREDV and ARH from 2001 to 2008 were obtained from three Bronx hospitals. After removing outliers, interpolating missing data, and standardizing variable values by scaling the data using z-scores, data were analyzed using Spearman rank tests and linear regression models for the full year and each season. Results: There were a total of 42,065 AREDV and 1,664 ARH at both Bronx hospitals. With the exception of a spring peak in AREDVs, AREDVs and ARHs follow a cyclical pattern, climbing in the fall, plateauing in the winter, dropping in the spring, and reaching a low in the summer. Among the 11 air quality, meteorological, and pollen count variables, temperature and tree pollen made the greatest contribution to AREDV with scaled coefficients of -0.337 and 0.311 respectively; equating to an additional AREDV for every 5.0-unit decrease in temperature and an additional AREDV for every 186.0-unit increase in tree pollen. These two variables were confirmed to have independent associations with AREDV prior to the data interpolation. Grass pollen was also found to have a relatively large contribution to AREDV during the summer with a scaled coefficient of 0.314, equating to an additional AREDV for every 2.3-unit increase in grass pollen. Conclusion: There are distinct peaks of increased AREDVs that are closely associated with increased tree pollen counts in the spring and decreasing temperatures in the fall. Early anticipation of these air quality, meteorological, and pollen factor changes based on ongoing surveillance could potentially guide clinical practice and minimize AREDVs in the Bronx.

High ambient levels of grass, weed and other pollen are associated with asthma admissions in children and adolescents: A large 5-year case-crossover study

BACKGROUND

Pollen is an important aeroallergen that triggers asthma exacerbations in children, but we know little about the impact of different pollen types in cities with varying climatic conditions and pollen seasons.

OBJECTIVES

We aimed to assess the role of ambient level of different types of pollen on a large time series of child and adolescent asthma hospitalizations in Sydney, Australia.

METHODS

Childhood asthma hospitalization and the daily ambient pollen concentrations of different species were collected in South-West Sydney. With a bidirectional case-crossover design, we fitted conditional logistic regression models to measure the associations between instantaneous and up to 3 days lagged effects of pollen concentrations on asthma hospitalizations after controlling for potential confounders and testing for interactions.

RESULTS

A total of 2098 children, more boys (59.7%) and 2-5 years old (62.6%), were hospitalized due to asthma. The geometric mean concentration of Cupressus, 7.88 [5.02] grains/m³ , was the highest during the study period. The increase from 75th to 90th percentile of grass (OR = 1.037, 95% CI 1.005-1.070), weed other than Plantago species (OR = 1.053, 95% CI 1.009-1.098) and unclassified pollen (OR = 1.034, 95% CI 1.010-1.058) were significantly associated with the odds of asthma hospitalizations. Boys were at greater risk of asthma exacerbations associated with grass (OR = 1.046, 95% CI 1.003-1.090) and unclassified pollen (OR = 1.041, 95% CI 1.010-1.073). There was evidence of effect modification by age groups for Cupressus, conifer, total tree and total pollen.

CONCLUSIONS

Although boys are more vulnerable to grass pollen, weed, and other pollen are also important triggers of asthma exacerbations in all children and adolescents. These findings are important for urban green space planning and the development of pollen monitoring systems for families with children at risk of asthma exacerbations during peak pollen seasons.

Short-term effect of outdoor mould spore exposure on prescribed allergy medication sales in Central France

BACKGROUND

Outdoor moulds are classically associated with exacerbations of asthma.

OBJECTIVE

The aim of this paper was to examine nasal allergy morbidity by studying the short-term relationship between mould spore exposure and daily sales of reimbursable anti-allergic treatment in central France.

METHODS

The relationship between daily changes in mould concentrations and daily sales obtained from the national healthcare database was analysed with generalized additive models, taking into account confounding factors such as air pollution, weather conditions, pollen counts, and days of the week.

RESULTS

During the study, the average total yearly number of treated people was around 10 000 over approximately 230 000 surveyed. The relative risk (95% CI confidence interval) of sales of oral antihistamines with topical treatment associated with an interquartile increase in mould concentration was significant for Cladosporium 1.079 [1.019-1.142] and Aspergillus-Penicillium (Asp-Pen) 1.051 [1.021-1.082] in the whole population. When the influence of age and sex was considered, the relationship was significant only in male children aged 0-12 years and those aged between 13 and 49 years for Cladosporium: 1.256 [1.081-1.460] and 1.151 [1.063-1.245], respectively. The relationship was also significant for Asp-Pen: 1.038 [1.003-1.075] for those aged between 13 and 49 years and 1.056 [1.007-1.108] for adults over 50 years of age.

CONCLUSION

The association between prescribed daily sales of oral antihistamines with topical treatment sales is associated with temporal changes to Cladosporium and Aspergillus-Penicillium in the whole population. When the influence of age and sex was considered, these two moulds contributed to prescribed medication sales only in the male general population.

Relationships between aeroallergen levels and hospital admissions for asthma in the Brussels-Capital Region: a daily time series analysis

BACKGROUND

Outdoor pollen grain and fungal spore concentrations have been associated with severe asthma exacerbations at the population level. The specific impact of each taxon and the concomitant effect of air pollution on these symptoms have, however, still to be better characterized. This study aimed to investigate the short-term associations between ambient concentrations of various aeroallergens and hospitalizations related to asthma in the Brussels-Capital Region (Belgium), an area recording especially high rates of admissions.

METHODS

Based on administrative records of asthma hospitalizations and regular monitoring of 11 tree/herbaceous pollen taxa and 2 fungal spore taxa, daily time series analyses covering the 2008-2013 period were performed. Effects up to 6 days after exposure were captured by combining quasi-Poisson regression with distributed lag models, adjusting for seasonal and long-term trends, day of the week, public holidays, mean temperature and relative humidity. Effect modification by age and air pollution (PM, NO₂, O₃) was tested.

RESULTS

A significant increase in asthma hospitalizations was observed for an interquartile range increase in grass (5.9%, 95% CI: 0.0, 12.0), birch (3.2%, 95% CI: 1.1, 5.3) and hornbeam (0.7%, 95% CI: 0.2, 1.3) pollen concentrations. For several taxa including grasses, an age modification effect was notable, the hospitalization risk tending to be higher in individuals younger than 60 years. Air pollutants impacted the relationships too: the risk appeared to be stronger for grass and birch pollen concentrations in case of high PM₁₀ and O₃ concentrations respectively.

CONCLUSIONS

These findings suggest that airborne grass, birch and hornbeam pollen are associated with severe asthma exacerbations in the Brussels region. These compounds appear to act in synergy with air pollution and to more specifically affect young and intermediate age groups. Most of these life-threatening events could theoretically be prevented with improved disease diagnosis/management and targeted communication actions.

Mapping allergenic pollen vegetation in UK to study environmental exposure and human health

Allergenic pollen is produced by the flowers of a number of trees, grasses and weeds found throughout the UK. Exposure to such pollen grains can exacerbate pollen-related asthma and allergenic conditions such as allergic rhinitis (hay fever). Maps showing the location of these allergenic taxa have many applications: they can be used to provide advice on risk assessments; combined with health data to inform research on health impacts such as respiratory hospital admissions; combined with weather data to improve pollen forecasting systems; or as inputs to pollen emission models. In this study we present 1km resolution maps of 12 taxa of trees, grass and weeds found in the UK. We have selected the main species recorded by the UK pollen network. The taxa mapped in this study were: Alnus (alder), Fraxinus (ash), Betula (birch), Corylus (hazel), Quercus (oak), Pinus (pine) and Salix (willow), Poaceae (grass), Artemisia (mugwort), Plantago (plantain), Rumex (dock, sorrels) and Urtica (nettle). We also focus on one high population centre and present maps showing local level detail around the city of London. Our results show the different geographical distributions of the 12 taxa of trees, weeds and grass, which can be used to study plants in the UK associated with allergy and allergic asthma. These maps have been produced in order to study environmental exposure and human health, although there are many possible applications. This novel method not only provides maps of many different plant types, but also at high resolution across regions of the UK, and we uniquely present 12 key plant taxa using a consistent methodology. To consider the impact on human health due to exposure of the pollen grains, it is important to consider the timing of pollen release, and its dispersal, as well as the effect on air quality, which is also discussed here.

Pollen exposure and hospitalization due to asthma exacerbations: daily time series in a European city

Exposure to pollen can contribute to increased hospital admissions for asthma exacerbation. This study applied an ecological time series analysis to examine associations between atmospheric concentrations of different pollen types and the risk of hospitalization for asthma in London from 2005 to 2011. The analysis examined short-term associations between daily pollen counts and hospital admissions in the presence of seasonal and long-term patterns, and allowed for time lags between exposure and admission. Models were adjusted for temperature, precipitation, humidity, day of week, and air pollutants. Analyses revealed an association between daily counts (continuous) of grass pollen and adult hospital admissions for asthma in London, with a 4-5-day lag. When grass pollen concentrations were categorized into Met Office pollen 'alert' levels, 'very high' days (vs. 'low') were associated with increased admissions 2-5 days later, peaking at an incidence rate ratio of 1.46 (95%, CI 1.20-1.78) at 3 days. Increased admissions were also associated with 'high' versus 'low' pollen days at a 3-day lag. Results from tree pollen models were inconclusive and likely to have been affected by the shorter pollen seasons and consequent limited number of observation days with higher tree pollen concentrations. Future reductions in asthma hospitalizations may be achieved by better understanding of environmental risks, informing improved alert systems and supporting patients to take preventive measures.

Analysis of correlation between pediatric asthma exacerbation and exposure to pollutant mixtures with association rule mining

OBJECTIVES

Traditional studies on effects of outdoor pollution on asthma have been criticized for questionable statistical validity and inefficacy in exploring the effects of multiple air pollutants, alone and in combination. Association rule mining (ARM), a method easily interpretable and suitable for the analysis of the effects of multiple exposures, could be of use, but the traditional interest metrics of support and confidence need to be substituted with metrics that focus on risk variations caused by different exposures.

METHODS

We present an ARM-based methodology that produces rules associated with relevant odds ratios and limits the number of final rules even at very low support levels (0.5%), thanks to post-pruning criteria that limit rule redundancy and control for statistical significance. The methodology has been applied to a case-crossover study to explore the effects of multiple air pollutants on risk of asthma in pediatric subjects.

RESULTS

We identified 27 rules with interesting odds ratio among more than 10,000 having the required support. The only rule including only one chemical is exposure to ozone on the previous day of the reported asthma attack (OR=1.14). 26 combinatory rules highlight the limitations of air quality policies based on single pollutant thresholds and suggest that exposure to mixtures of chemicals is more harmful, with odds ratio as high as 1.54 (associated with the combination day0 SO₂, day0 NO, day0 NO₂, day1 PM).

CONCLUSIONS

The proposed method can be used to analyze risk variations caused by single and multiple exposures. The method is reliable and requires fewer assumptions on the data than parametric approaches. Rules including more than one pollutant highlight interactions that deserve further investigation, while helping to limit the search field.

The effects of air pollution on asthma hospital admissions in Adelaide, South Australia, 2003-2013: time-series and case-crossover analyses

BACKGROUND

Air pollution can have adverse health effects on asthma sufferers, but the effects vary with geographic, environmental and population characteristics. There has been no long time-series study in Australia to quantify the effects of environmental factors including pollen on asthma hospitalizations.

OBJECTIVES

This study aimed to assess the seasonal impact of air pollutants and aeroallergens on the risk of asthma hospital admissions for adults and children in Adelaide, South Australia.

METHODS

Data on hospital admissions, meteorological conditions, air quality and pollen counts for the period 2003-2013 were sourced. Time-series analysis and case-crossover analysis were used to assess the short-term effects of air pollution on asthma hospitalizations. For the time-series analysis, generalized log-linear quasi-Poisson and negative binomial regressions were used to assess the relationships, controlling for seasonality and long-term trends using flexible spline functions. For the case-crossover analysis, conditional logistic regression was used to compute the effect estimates with time-stratified referent selection strategies.

RESULTS

A total of 36,024 asthma admissions were considered. Findings indicated that the largest effects on asthma admissions related to PM_2.5 , NO₂ , PM₁₀ and pollen were found in the cool season for children (0-17 years), with the 5-day cumulative effects of 30.2% (95% CI: 13.4-49.6%), 12.5% (95% CI: 6.6-18.7%), 8.3% (95% CI: 2.5-14.4%) and 4.2% (95% CI: 2.2-6.1%) increases in risk of asthma hospital admissions per 10 unit increments, respectively. The largest effect for ozone was found in the warm season for children with the 5-day cumulative effect of an 11.7% (95% CI: 5.8-17.9%) increase in risk of asthma hospital admissions per 10 ppb increment in ozone level.

CONCLUSION

Findings suggest that children are more vulnerable and the associations between exposure to air pollutants and asthma hospitalizations tended to be stronger in the cool season compared to the warm season, with the exception of ozone. This study has important public health implications and provides valuable evidence for the development of policies for asthma management.

You sneeze, you lose:: The impact of pollen exposure on cognitive performance during high-stakes high school exams

Pollen is known to cause allergic reactions and affect cognitive performance in around 20% of the population. Although pollen season peaks when students take high-stakes exams, the effect of pollen allergies on school performance has received nearly no attention from economists. Using a student fixed effects model and administrative Norwegian data, this paper finds that increasing the ambient pollen levels by one standard deviation at the mean leads to a 2.5% standard deviation decrease in test scores, with potentially larger effects for allergic students. There also appear to be longer-run effects. The findings imply that random increases in pollen counts reduce test scores for allergic students relative to their peers, who consequently will be at a disadvantage when competing for jobs or higher education. This paper contributes to the literature by illuminating the interplay between individual health and human capital accumulation, which in turn can impact long-run economic growth.

Associations between outdoor fungal spores and childhood and adolescent asthma hospitalizations

BACKGROUND

Childhood asthma is a significant public health problem and severe exacerbations can result in diminished quality of life and hospitalization.

OBJECTIVE

We sought to examine the contribution of outdoor fungi to childhood and adolescent asthma hospitalizations.

METHODS

The Melbourne Air Pollen Children and Adolescent study is a case-crossover study of 644 children and adolescents (aged 2-17 years) hospitalized for asthma. The Melbourne Air Pollen Children and Adolescent study collected individual data on human rhinovirus infection and sensitization to Alternaria and Cladosporium and daily counts of ambient concentrations of fungal spores, pollen, and air pollutants. Conditional logistic regression models were used to assess associations with increases in spore counts while controlling for potential confounding and testing interactions.

RESULTS

Exposure to Alternaria (adjusted odds ratio [aOR], 1.07; 95% CI, 1.03-1.11), Leptosphaeria (aOR, 1.05; 95% CI, 1.02-1.07), Coprinus (aOR, 1.04; 95% CI, 1.01-1.07), Drechslera (aOR, 1.03; 95% CI, 1.00-1.05), and total spores (aOR, 1.05; 95% CI, 1.01-1.09) was significantly associated with child asthma hospitalizations independent of human rhinovirus infection. There were significant lagged effects up to 3 days with Alternaria, Leptosphaeria, Cladosporium, Sporormiella, Coprinus, and Drechslera. Some of these associations were significantly greater in participants with Cladosporium sensitization.

CONCLUSIONS

Exposures to several outdoor fungal spore taxa, including some not reported in previous research, are associated with the risk of child and adolescent asthma hospitalization, particularly in individuals sensitized to Cladosporium. We need further studies to examine cross-reactivity causing asthma exacerbations. Identifying sensitization to multiple fungal allergens in children with asthma could support the design and implementation of more effective strategies to prevent asthma exacerbations.

Differences in grass pollen allergen exposure across Australia

Objective: Allergic rhinitis and allergic asthma are important chronic diseases posing serious public health issues in Australia with associated medical, economic, and societal burdens. Pollen are significant sources of clinically relevant outdoor aeroallergens, recognised as both a major trigger for, and cause of, allergic respiratory diseases. This study aimed to provide a national, and indeed international, perspective on the state of Australian pollen data using a large representative sample.

Methods: Atmospheric grass pollen concentration is examined over a number of years within the period 1995 to 2013 for Brisbane, Canberra, Darwin, Hobart, Melbourne, and Sydney, including determination of the ‘clinical’ grass pollen season and grass pollen peak.

Results: The results of this study describe, for the first time, a striking spatial and temporal variability in grass pollen seasons in Australia, with important implications for clinicians and public health professionals, and the Australian grass pollen‐allergic community.

Conclusions: These results demonstrate that static pollen calendars are of limited utility and in some cases misleading. This study also highlights significant deficiencies and limitations in the existing Australian pollen monitoring and data.

Implications: Establishment of an Australian national pollen monitoring network would help facilitate advances in the clinical and public health management of the millions of Australians with asthma and allergic rhinitis.

Regional and seasonal variation in airborne grass pollen levels between cities of Australia and New Zealand

Although grass pollen is widely regarded as the major outdoor aeroallergen source in Australia and New Zealand (NZ), no assemblage of airborne pollen data for the region has been previously compiled. Grass pollen count data collected at 14 urban sites in Australia and NZ over periods ranging from 1 to 17 years were acquired, assembled and compared, revealing considerable spatiotemporal variability. Although direct comparison between these data is problematic due to methodological differences between monitoring sites, the following patterns are apparent. Grass pollen seasons tended to have more than one peak from tropics to latitudes of 37°S and single peaks at sites south of this latitude. A longer grass pollen season was therefore found at sites below 37°S, driven by later seasonal end dates for grass growth and flowering. Daily pollen counts increased with latitude; subtropical regions had seasons of both high intensity and long duration. At higher latitude sites, the single springtime grass pollen peak is potentially due to a cooler growing season and a predominance of pollen from C₃ grasses. The multiple peaks at lower latitude sites may be due to a warmer season and the predominance of pollen from C₄ grasses. Prevalence and duration of seasonal allergies may reflect the differing pollen seasons across Australia and NZ. It must be emphasized that these findings are tentative due to limitations in the available data, reinforcing the need to implement standardized pollen-monitoring methods across Australasia. Furthermore, spatiotemporal differences in grass pollen counts indicate that local, current, standardized pollen monitoring would assist with the management of pollen allergen exposure for patients at risk of allergic rhinitis and asthma.

Winter circulation weather types and hospital admissions for respiratory diseases in Galicia, Spain

The link between various pathologies and atmospheric conditions has been a constant topic of study over recent decades in many places across the world; knowing more about it enables us to pre-empt the worsening of certain diseases, thereby optimizing medical resources. This study looked specifically at the connections in winter between respiratory diseases and types of atmospheric weather conditions (Circulation Weather Types, CWT) in Galicia, a region in the north-western corner of the Iberian Peninsula. To do this, the study used hospital admission data associated with these pathologies as well as an automatic classification of weather types. The main result obtained was that weather types giving rise to an increase in admissions due to these diseases are those associated with cold, dry weather, such as those in the east and south-east, or anticyclonic types. A second peak was associated with humid, hotter weather, generally linked to south-west weather types. In the future, this result may help to forecast the increase in respiratory pathologies in the region some days in advance.

[Seasonality in asthma: Impact and treatments]

The role of seasons should be taken into account in the management of asthma. The environment varies between seasons and it is well documented that asthma is modulated by environment. Viruses cause asthma exacerbations peak, in winter, in adults while the peak is present in September in children. Allergens are probably a less powerful source of asthma exacerbation than viruses but pollen involvement in spring and summer and dust mites in autumn are indisputable. Air pollutants, present in summer during the hottest periods, are also highly involved in asthma exacerbations. Indoor air pollution, in winter, is also implicated in asthma disease. All these environmental factors are synergistic and increase the risk of asthma exacerbation. Therapies should be adapted to each season depending on environmental factors potentially involved in the asthma disease.

Trans-disciplinary research in synthesis of grass pollen aerobiology and its importance for respiratory health in Australasia

Grass pollen is a major trigger for allergic rhinitis and asthma, yet little is known about the timing and levels of human exposure to airborne grass pollen across Australasian urban environments. The relationships between environmental aeroallergen exposure and allergic respiratory disease bridge the fields of ecology, aerobiology, geospatial science and public health. The Australian Aerobiology Working Group comprised of experts in botany, palynology, biogeography, climate change science, plant genetics, biostatistics, ecology, pollen allergy, public and environmental health, and medicine, was established to systematically source, collate and analyse atmospheric pollen concentration data from 11 Australian and six New Zealand sites. Following two week-long workshops, post-workshop evaluations were conducted to reflect upon the utility of this analysis and synthesis approach to address complex multidisciplinary questions. This Working Group described i) a biogeographically dependent variation in airborne pollen diversity, ii) a latitudinal gradient in the timing, duration and number of peaks of the grass pollen season, and iii) the emergence of new methodologies based on trans-disciplinary synthesis of aerobiology and remote sensing data. Challenges included resolving methodological variations between pollen monitoring sites and temporal variations in pollen datasets. Other challenges included "marrying" ecosystem and health sciences and reconciling divergent expert opinion. The Australian Aerobiology Working Group facilitated knowledge transfer between diverse scientific disciplines, mentored students and early career scientists, and provided an uninterrupted collaborative opportunity to focus on a unifying problem globally. The Working Group provided a platform to optimise the value of large existing ecological datasets that have importance for human respiratory health and ecosystems research. Compilation of current knowledge of Australasian pollen aerobiology is a critical first step towards the management of exposure to pollen in patients with allergic disease and provides a basis from which the future impacts of climate change on pollen distribution can be assessed and monitored.

Allergy test: Seasonal allergens and performance in school

Seasonal pollen allergies affect approximately 1 in 5 school age children. Clinical research has established that these allergies result in large and consistent decrements in cognitive functioning, problem solving ability and speed, focus and energy. However, compared to air pollution, the impact of pollen and seasonal allergies on achievement in schools has received less attention from economists. Here, I use data on daily pollen counts merged with school district data to assess whether variation in the airborne pollen that induces seasonal allergies is associated with performance on state reading and math assessments. I find substantial and robust effects: A one standard deviation in ambient pollen levels reduces the percent of 3rd graders passing ELA assessments by between 0.2 and 0.3 standard deviations, and math assessments by between about 0.3 and 0.4 standard deviations. I discuss the empirical limitations as well as policy implications of this reduced-form estimate of pollen levels in a community setting.

A new 'bio-comfort' perspective for Melbourne based on heat stress, air pollution and pollen

Humans are at risk from exposure to extremes in their environment, yet there is no consistent way to fully quantify and understand the risk when considering more than just meteorological variables. An outdoor 'bio-comfort' threshold is defined for Melbourne, Australia using a combination of heat stress, air particulate concentration and grass pollen count, where comfortable conditions imply an ideal range of temperature, humidity and wind speed, acceptable levels of air particulates and a low pollen count. This is a new approach to defining the comfort of human populations. While other works have looked into the separate impacts of different variables, this is the first time that a unified bio-comfort threshold is suggested. Composite maps of surface pressure are used to illustrate the genesis and evolution of the atmospheric structures conducive to an uncomfortable day. When there is an uncomfortable day due to heat stress conditions in Melbourne, there is a high pressure anomaly to the east bringing warm air from the northern interior of Australia. This anomaly is part of a slow moving blocking high originating over the Indian Ocean. Uncomfortable days due to high particulate levels have an approaching cold front. However, for air particulate cases during the cold season there are stable atmospheric conditions enhanced by a blocking high emanating from Australia and linking with the Antarctic continent. Finally, when grass pollen levels are high, there are northerly winds carrying the pollen from rural grass lands to Melbourne, due to a stationary trough of low pressure inland. Analysis into days with multiple types of stress revealed that the atmospheric signals associated with each type of discomfort are present regardless of whether the day is uncomfortable due to one or multiple variables. Therefore, these bio-comfort results are significant because they offer a degree of predictability for future uncomfortable days in Melbourne.

Prevalence and clinical relevance of allergic rhinitis in patients with classic asthma and cough variant asthma

BACKGROUND

A clinically relevant relationship between classic asthma and allergic rhinitis has been reported. However, the possible link between cough variant asthma (CVA) and allergic rhinitis remains unknown.

OBJECTIVES

To clarify the prevalence and clinical relevance of perennial allergic rhinitis or seasonal allergic rhinitis in CVA patients compared to classic asthma patients.

METHODS

We retrospectively studied adult patients with classic asthma (n = 190) and those with CVA (n = 83). The prevalence of perennial allergic rhinitis or seasonal allergic rhinitis and associations of concomitant perennial or seasonal allergic rhinitis with asthma severity, forced expiratory volume in 1 s (% predicted), fractional exhaled nitric oxide (FeNO) levels, and eosinophil proportions in sputum and blood were analyzed in the two groups.

RESULTS

The prevalence of perennial allergic rhinitis and/or seasonal allergic rhinitis was significantly higher in classic asthma patients than in CVA patients (all p < 0.05). Concomitant perennial allergic rhinitis was associated with higher FeNO levels and eosinophil proportions in sputum and blood in classic asthma patients (p = 0.035, p = 0.036, and p = 0.008, respectively) and with higher asthma severity, FeNO levels, and sputum eosinophil proportions in CVA patients (p = 0.031, p = 0.007, and p = 0.010, respectively). Concomitant seasonal allergic rhinitis was only associated with higher sputum eosinophil proportions in CVA patients with active rhinitis symptoms during the sensitized pollen season (p = 0.025).

CONCLUSIONS

Perennial allergic rhinitis may be relevant for CVA patients as well as classic asthma patients by consistently augmenting eosinophilic lower airway inflammation.

[Health impact of exposure to pollens: A review of epidemiological studies]

The aim of this review is to describe the health impact of exposure to pollen based on recently published epidemiological studies. The methodology chapter, describes a review of the literature and outlines important elements of these studies: measurement of exposure to pollens, study types used, study populations and the health indicators related to pollen exposure. In this review, two types of studies have been used to assess the epidemiological evidence of short-term links between pollen exposure and hay fever or asthma. Ecological time-series studies use daily indicators of asthma exacerbations (emergency room admissions or hospitalizations), consultations for rhinitis or conjunctivitis, or anti-allergic drug consumption within general population. Panel studies relate measurements of pollen grain concentrations to nasal, ocular and bronchial symptom severity in a group of subjects sensitized to a specific pollen, monitored during the pollen season. In both cases, the studies show a relationship on a day-to-day basis between health indicators and daily rates of atmospheric pollen collected by a pollen trap. These studies take into account confounding factors, such as air pollution, weather factors and sometimes exposure to outdoor molds. Unlike earlier studies, more and more studies focus on the shape of the dose-response relationship and the lag between pollen exposure and symptoms. Only rarely, individual susceptibility factors, the clinical phenomenon of priming and polysensitization are reported. Thus, ecological time-series studies and panel studies assess respectively the impact of pollen exposure in the general population and in groups of sensitized patients. Using appropriate statistical tools, these studies provide insight into the shape of the dose-response relationship, with a potential threshold below which symptoms are absent, then a linear relationship for nasal, ocular and bronchial symptoms and a plateau where the symptoms do not increase despite the continued increase in pollen.

Persistent pollen exposure during infancy is associated with increased risk of subsequent childhood asthma and hayfever

BACKGROUND

Few studies have focused on pollen exposure and asthma in children. None have examined associations between persistent exposure to pollen in infancy and aeroallergen sensitisation and asthma in childhood.

OBJECTIVES

To examine the association between higher ambient levels of pollen in the first 3-6 months of life and risk of eczema, sensitization to food and aeroallergens at 2 years and asthma or hayfever at age 6-7 years combined.

METHODS

Using a birth cohort of 620 infants with a family history of allergic disease born between 1990 and 1994, we examined risk of eczema or allergic sensitization (SPT > 3 mm to at least one of cow's milk, egg white, peanut, house dust-mite, rye grass, and cat dander) by age 2 and asthma or hayfever at age 6-7. Daily ambient levels of pollen were measured during this period.

RESULTS

Cumulative exposure to pollen concentrations up to 6 months was associated with aeroallergen sensitization with the highest risk occurring at 3 months (aOR = 1.34, 95% CI 1.06-1.72). Cumulative exposure to pollen up to 3 months was also associated with hayfever (aOR = 1.14, 95% CI 1.009-1.29) and between 4 and 6 months exposure with asthma only (aOR=1.35, 95% CI 1.07-1.72).

CONCLUSION

Persistent pollen exposure in infancy appears to increase the risk of asthma and hayfever in children. These results support the hypothesis that there is a critical window of opportunity in early development which may be important for modification of allergic outcomes.

Grass pollen allergy in children and adolescents-symptoms, health related quality of life and the value of pollen prognosis

INTRODUCTION

An association between pollen count (Poaceae) and symptoms is well known, but to a lesser degree the importance of priming and lag effects. Also, threshold levels for changes in symptom severity need to be validated. The present study aims to investigate the relationship between pollen counts, symptoms and health related quality of life (HRQL), and to validate thresholds levels, useful in public pollen warnings.

MATERIAL AND METHODS

Children aged 7-18 with grass pollen allergy filled out a symptom diary during the pollen season for nose, eyes and lung symptoms, as well as a HRQL questionnaire every week. Pollen counts were monitored using a volumetric spore trap.

RESULTS

89 (91%) of the included 98 children completed the study. There was a clear association between pollen count, symptom severity and HRQL during the whole pollen season, but no difference in this respect between early and late pollen season. There was a lag effect of 1-3 days after pollen exposure except for lung symptoms. We found only two threshold levels, at 30 and 80 pollen grains/m(3) for the total symptom score, not three as is used today. The nose and eyes reacted to low doses, but for the lung symptoms, symptom strength did hardly change until 50 pollen grains/m(3).

CONCLUSION

Grass pollen has an effect on symptoms and HRQL, lasting up to 5 days after exposure. Symptoms from the lungs appear to have higher threshold levels than the eyes and the nose. Overall symptom severity does not appear to change during the course of season. Threshold levels need to be revised. We suggest a traffic light model for public pollen warnings directed to children, where green signifies "no problem", yellow signifies "can be problems, especially if you are highly sensitive" and red signifies "alert - take action".

The influence of sensitisation to pollens and moulds on seasonal variations in asthma attacks

No large study has described the seasonal variation in asthma attacks in population-based asthmatics in whom sensitisation to allergen has been measured.

2637 young adults with asthma living in 15 countries reported the months in which they usually had attacks of asthma and had skin-prick tests performed. Differences in seasonal patterns by sensitisation status were assessed using generalised estimating equations.

Most young adults with asthma reported periods of the year when their asthma attacks were more common (range: 47% in Sweden to 86% in Spain). Seasonal variation in asthma was not modified by sensitisation to house dust mite or cat allergens. Asthmatics sensitised to grass, birch and Alternaria allergens had different seasonal patterns to those not sensitised to each allergen, with some geographical variation. In southern Europe, those sensitised to grass allergens were more likely to report attacks occurred in spring or summer than in winter (OR March/April 2.60, 95% CI 1.70–3.97; OR May/June 4.43, 95% CI 2.34–8.39) and smaller later peaks were observed in northern Europe (OR May/June 1.25, 95% CI 0.60–2.64; OR July/August 1.66, 95% CI 0.89–3.10). Asthmatics reporting hay fever but who were not sensitised to grass showed no seasonal variations.

Seasonal variations in asthma attacks in young adults are common and are different depending on sensitisation to outdoor, but not indoor, allergens.

Seasonal variation in asthma attacks is associated with sensitisation to pollens and moulds, but not indoor allergenshttp://ow.ly/nsuRS

Influence of pollen level on hospitalizations for asthma

The effect of pollen level on asthma hospitalizations is still under debate. The aim of this study was to analyze hospital admissions due to asthma and its relation with environmental pollen and meteorological factors. During 13 years, we included every patient admitted with asthma as primary or secondary diagnosis. For this purpose, we used a case-crossover analysis to compare pollen concentrations at the time of admission with values of the same variables 2 to 6 days before admission. We included 6,687 hospital admissions. High maximum temperature and low humidity were associated with lower risk of asthma admissions. High mean pollen levels exerted a moderate effect and high maximum pollen levels led to a dramatic increase of hospital admissions due to asthma, especially among females. In conclusion, environmental pollen level increases the risk of asthma hospital admissions.