Urbanity as a determinant of exposure to grass pollen in Helsinki Metropolitan area, Finland

Association between short-term pollen exposure and blood pressure in adults: A repeated-measures study

BACKGROUND

Recent studies have related high pollen concentrations to increased cardiovascular morbidity and mortality, yet very little research concerns pre-clinical cardiovascular health, including effects on blood pressure (BP). The EPOCHAL panel study investigated the exposure-response relationship between ambient pollen exposure and systolic and diastolic BP in adults.

METHODS

BP was measured in 302 adults with and in 94 without pollen allergy during the pollen season, on approximately 16 days per person (6253 observations). Average individually-relevant pollen exposure in the 96 h prior to each BP measurement was calculated by summing up the averages of all ambient pollen concentrations to which the individual was found to be sensitized in a skin prick test, and which originated from seven highly allergenic pollen types (hazel, alder, birch, ash, grasses, mugwort and ragweed). Generalized additive mixed models were used to study the association between mean individually-relevant pollen exposure in the last 96 h and BP, adjusting for individual and environmental time-varying covariates. Effect modification by pollen allergy status, sex and BMI was evaluated.

RESULTS

Positive non-linear associations between individually-relevant pollen exposure and both systolic and diastolic BP were found in the allergic but not in the non-allergic group. BP increased sharply for exposures from zero to 60/80 pollen/m3 (diastolic/systolic BP), followed by a tempered further increase at higher concentrations. Increases of 2.00 mmHg [95% confidence interval (CI): 0.80-3.19] in systolic and 1.51 mmHg [95% CI: 0.58-2.45] in diastolic BP were associated with 96-h average pollen exposure of 400 pollen/m3, compared to no exposure. Obesity and female sex were associated with larger BP increases.

CONCLUSIONS

The finding that short-term pollen concentration is associated with increased systolic and diastolic BP in persons with pollen allergy strengthens the evidence that pollen may cause systemic health effects and trigger cardiovascular events.

Comparison of Olea pollen sampling between gravimetric and volumetric traps (NW of Morocco)

Olea pollen is considered one of the most critical causes of respiratory allergic disease in the Mediterranean region, contributing to different symptoms in allergic sufferers. Due to the high increase in the prevalence of olive pollen caused by the expansion of cultivated areas especially in the Mediterranean region, the aim of this study was to examine the Olea pollen sampling efficiency between gravimetric and volumetric pollen traps over the period 2018-2022. Our data demonstrated that Olea pollen season start-date was generally recorded earlier with volumetric trap than shown with gravimetric method. Moreover, the peak dates occurred mainly in May for the years studied. Across the entire period, the greatest pollen concentrations were reached in the week 11th and >60 % of the total Olea pollen were already reached after the ninth week of sampling in 2020. In general, the evolution of pollen sampling for both methods demonstrates similar temporal development. Variations in the seasonal pollen integral could be attributed to the elevation above ground level at which the traps were placed, exposure to regional winds, the influence of long-range transported pollen and the mode of pollen transport. The findings indicate that the gravimetric method was equally practical as the volumetric method in estimating airborne pollen.

The Built Environment and Pediatric Health

Buildings, parks, and roads are all elements of the "built environment," which can be described as the human-made structures that comprise the neighborhoods and communities where people live, work, learn, and recreate (https://www.epa.gov/smm/basic-information-about-built-environment). The design of communities where children and adolescents live, learn, and play has a profound impact on their health. Moreover, the policies and practices that determine community design and the built environment are a root cause of disparities in the social determinants of health that contribute to health inequity. An understanding of the links between the built environment and pediatric health will help to inform pediatricians' and other pediatric health professionals' care for patients and advocacy on their behalf. This technical report describes the range of pediatric physical and mental health conditions influenced by the built environment, as well as historical and persistent effects of the built environment on health disparities. The accompanying policy statement outlines community design solutions that can improve pediatric health and health equity, including opportunities for pediatricians and the health care sector to incorporate this knowledge in patient care, as well as to play a role in advancing a health-promoting built environment for all children and families.

Outdoor airborne allergens: Characterization, behavior and monitoring in Europe

Aeroallergens or inhalant allergens, are proteins dispersed through the air and have the potential to induce allergic conditions such as rhinitis, conjunctivitis, and asthma. Outdoor aeroallergens are found predominantly in pollen grains and fungal spores, which are allergen carriers. Aeroallergens from pollen and fungi have seasonal emission patterns that correlate with plant pollination and fungal sporulation and are strongly associated with atmospheric weather conditions. They are released when allergen carriers come in contact with the respiratory system, e.g. the nasal mucosa. In addition, due to the rupture of allergen carriers, airborne allergen molecules may be released directly into the air in the form of micronic and submicronic particles (cytoplasmic debris, cell wall fragments, droplets etc.) or adhered onto other airborne particulate matter. Therefore, aeroallergen detection strategies must consider, in addition to the allergen carriers, the allergen molecules themselves. This review article aims to present the current knowledge on inhalant allergens in the outdoor environment, their structure, localization, and factors affecting their production, transformation, release or degradation. In addition, methods for collecting and quantifying aeroallergens are listed and thoroughly discussed. Finally, the knowledge gaps, challenges and implications associated with aeroallergen analysis are described.

A comprehensive aerobiological study of the airborne pollen in the Irish environment

Respiratory allergies triggered by pollen allergens represent a significant health concern to the Irish public. Up to now, Ireland has largely refrained from participating in long-term aerobiological studies. Recently, pollen monitoring has commenced in several sampling locations around Ireland. The first results of the pollen monitoring campaigns for Dublin (urban) and Carlow (rural) concerning the period 2017-2019 and 2018-2019, respectively, are presented herein. Additional unpublished pollen data from 1978-1980 and, 2010-2011 were also incorporated in creating the first pollen calendar for Dublin. During the monitoring period over 60 pollen types were identified with an average Annual Pollen Integral (APIn) of 32,217 Pollen × day/m³ for Dublin and 78,411 Pollen × day/m³ for Carlow. The most prevalent pollen types in Dublin were: Poaceae (32%), Urticaceae (29%), Cupressaceae/Taxaceae (11%), Betula (10%), Quercus (4%), Pinus (3%), Fraxinus (2%), Alnus (2%) and Platanus (1%). The predominant pollen types in Carlow were identified as Poaceae (70%), Urticaceae (12%), Betula (10%), Quercus (2%), Fraxinus (1%) and Pinus (1%). These prevalent pollen types increased in annual pollen concentration in both locations from 2018 to 2019 except for Fraxinus. Although higher pollen concentrations were observed for the Carlow (rural) site a greater variety of pollen types were identified for the Dublin (urban) site. The general annual trend in the pollen season began with the release of tree pollen in early spring, followed by the release of grass and herbaceous pollen which dominated the summer months with the annual pollen season coming to an end in October. This behaviour was illustrated for 21 different pollen types in the Dublin pollen calendar. The correlation between ambient pollen concentration and meteorological parameters was also examined and differed greatly depending on the location and study year. A striking feature was a substantial fraction of the recorded pollen sampled in Dublin did not correlate with the prevailing wind directions. However, using non-parametric wind regression, specific source regions could be determined such as Alnus originating from the Southeast, Betula originating from the East and Poaceae originating from the Southwest.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10453-022-09751-w.

Data mining assessment of Poaceae pollen influencing factors and its environmental implications

Poaceae pollen is highly allergenic, with a marked contribution to the pollen worldwide allergy prevalence. Pollen counts are defined by the species present in the considered area, although year-to-year oscillations may be triggered by different parameters, among which are weather conditions. Due to the predominant role of Poaceae pollen in the allergenicity in urban green areas, the aim of this study was the analysis of pollen trends and the influence of meteorology to forecast relevant variations in airborne pollen levels. The study was carried out during the 1993-2020 period in Ourense, in NW Iberian Peninsula. We used a volumetric Lanzoni VPPS 2000 trap for recording Poaceae airborne pollen grains, and meteorological daily data were obtained from the Galician Institute for Meteorology and Oceanography. The main indexes of the pollen season and their trends were calculated. A correlation analysis and 'C5.0 Decision Trees and Rule-Based Models' data mining algorithm were applied to determine the influence of meteorological conditions on pollen levels. We detected atmospheric Poaceae pollen during 139 days on average, mainly from April to August. The mean pollen grains amount recorded during the pollen season was 4608 pollen grains, with the pollen maximum peak of 276 pollen/m³ on 27 June. We found no statistically significant trends and slight slopes for the seasonal indexes, similarly to previous Poaceae studies in the same region. The calculated C5.0 model offered defined results, indicating that the combination of mean temperature above 17.46 °C and sunlight exposure higher than 12.7 h is conductive to significantly high pollen levels. The obtained results make possible the identification of risk moments during the pollen season for the activation of protective measures for sensitized population to grass pollen.

Atmospheric transport reveals grass pollen dispersion distances

Identifying the origin of bioaerosols is of central importance in many biological disciplines, such as human health, agriculture, forestry, aerobiology and conservation. Modelling sources, transportation pathways and sinks can reveal how bioaerosols vary in the atmosphere and their environmental impact. Grass pollen are particularly important due to their widely distributed source areas, relatively high abundance in the atmosphere and high allergenicity. Currently, studies are uncertain regarding sampler representability between distance and sources for grass pollen. Using generalized linear modelling, this study aimed to analyse this relationship further by answering the question of distance-to-source area contribution. Grass pollen concentrations were compared between urban and rural locations, located 6.4 km apart, during two years in Worcestershire, UK. We isolated and refined vegetation areas at 100 m × 100 m using the 2017 CEH Crop Map and conducted atmospheric modelling using HYSPLIT to identify which source areas could contribute pollen. Pollen concentrations were then modelled with source areas and meteorology using generalized linear mixed-models with three temporal variables as random variation. We found that the Seasonal Pollen Integral for grass pollen varied between both years and location, with the urban location having higher levels. Day of year showed higher temporal variation than the diurnal or annual variables. For the urban location, grass source areas within 30 km had positive significant effects in predicting grass pollen concentrations, while source areas within 2-10 km were important for the rural one. The source area differential was likely influenced by an urban-rural gradient that caused differences in the source area contribution. Temperature had positive highly significant effects on both locations while precipitation affected only the rural location. Combining atmospheric modelling, vegetation source maps and generalized linear modelling was found to be a highly accurate tool to identify transportation pathways of bioaerosols in landscape environments.

Outdoor pollen concentration is not associated with exercise-induced bronchoconstriction in children

BACKGROUND

Free running exercise test outdoors is an important method to diagnose asthma in children. However, the extent of how much exposure to pollens of outdoor air affects the results of the test is not known.

METHODS

We analyzed all reliable exercise challenge tests with impulse oscillometry in children (n = 799) between January 2012 and December 2014 in Tampere University Hospital. Pollen concentrations at the time of the test were collected from the register of Biodiversity Unit of the University of Turku. We compared the frequency of exercise-induced bronchoconstriction and pollen concentrations.

RESULTS

The analyses were restricted to birch and alder pollen as high counts of grass and mugwort pollen were so infrequent. The relative change in resistance at 5 Hz after exercise or the frequency of exercise-induced bronchoconstriction were not related to alder or birch pollen concentrations over 10 grains/m³ (p = 0.125-0.398). In logistic regression analysis comparing the effects of alder or birch pollen concentrations, immunoglobulin E (IgE)-mediated alder or birch allergy and absolute humidity over 10 g/m³ only absolute humidity was independently associated with change in airway resistance (odds ratio [OR]: 0.32, confidence interval [CI]: 0.13-0.67, p: 0.006).

CONCLUSIONS

In our large clinical sample, outdoor air pollen concentration was not associated with the probability of exercise-induced bronchoconstriction in free running test in children while low absolute humidity was the best predictor of airway obstruction.

Long-Term Pollen Monitoring in the Benelux: Evaluation of Allergenic Pollen Levels and Temporal Variations of Pollen Seasons

Airborne pollen is a major cause of allergic rhinitis, affecting between 10 and 30% of the population in Belgium, the Netherlands, and Luxembourg (Benelux). Allergenic pollen is produced by wind pollinating plants and released in relatively low to massive amounts. Current climate changes, in combination with increasing urbanization, are likely to affect the presence of airborne allergenic pollen with respect to exposure intensity, timing as well as duration. Detailed analysis of long-term temporal trends at supranational scale may provide more comprehensive insight into these phenomena. To this end, the Spearman correlation was used to statistically compare the temporal trends in airborne pollen concentration monitored at the aerobiological stations which gathered the longest time-series (30–44 years) in the Benelux with a focus on the allergenic pollen taxa: Alnus, Corylus, Betula, Fraxinus, Quercus, Platanus, Poaceae, and Artemisia. Most arboreal species showed an overall trend toward an increase in the annual pollen integral and peak values and an overall trend toward an earlier start and end of the pollen season, which for Betula resulted in a significant decrease in season length. For the herbaceous species (Poaceae and Artemisia), the annual pollen integral and peak values showed a decreasing trend. The season timing of Poaceae showed a trend toward earlier starts and longer seasons in all locations. In all, these results show that temporal variations in pollen levels almost always follow a common trend in the Benelux, suggesting a similar force of climate change-driven factors, especially for Betula where a clear positive correlation was found between changes in temperature and pollen release over time. However, some trends were more local-specific indicating the influence of other environmental factors, e.g., the increasing urbanization in the surroundings of these monitoring locations. The dynamics in the observed trends can impact allergic patients by increasing the severity of symptoms, upsetting the habit of timing of the season, complicating diagnosis due to overlapping pollen seasons and the emergence of new symptoms due allergens that were weak at first.

The effect of sampling height on grass pollen concentrations in different urban environments in the Helsinki Metropolitan Area, Finland

Introduction

It is important to study potential differences in pollen concentrations between sampling heights because of diverse outdoor and indoor activity of humans (exposure) at different height levels in urban environments. Previous studies have investigated the effect of height on pollen concentrations based on just one or a few sampling points. We studied the effect of sampling height on grass pollen concentrations in several urban environments with different levels of urbanity.

Methods

This study was conducted in the Helsinki Metropolitan Area, Finland, in 2013 during the pollen season of grasses. Pollen grains were monitored in eight different points in the morning and afternoon. Rotorod-type samplers were attached on sampling poles at the heights of 1.5 meters and 4 meters.

Results

Grass pollen concentrations were on average higher at the height of 1.5 meters (Helsinki mean 5.24 grains / m³; Espoo mean 75.71 grains / m³) compared to the height of 4 meters (Helsinki mean 3.84 grains / m³; Espoo mean 37.42 grains / m³) with a difference of 1.40 grains / m³ (95% CI -0.21 to 3.01) in Helsinki, and 38.29 grains / m³ (7.52 to 69.07) in Espoo, although not always statistically significant. This was detected both in the morning and in the afternoon. However, in the most urban sites the levels were lower at 1.5 meters compared to 4 meters, whereas in the least urban sites the concentrations were higher at 1.5 meters. In linear regression models with interaction terms, the modifying effect of urbanity on concentration-height relation was statistically significant in both cities. The effect of urbanity on pollen concentrations at both heights was stronger in less urban Espoo.

Conclusions

The present study provides evidence that height affects the abundance and distribution of grass pollen in urban environments, but this effect depends on the level of urbanity.

Land-Use and Height of Pollen Sampling Affect Pollen Exposure in Munich, Germany

Airborne pollen concentrations vary depending on the location of the pollen trap with respect to the pollen sources. Two Hirst-type pollen traps were analyzed within the city of Munich (Germany): one trap was located 2 m above ground level (AGL) and the other one at rooftop (35 m AGL), 4.2 km apart. In general, 1.4 ± 0.5 times higher pollen amounts were measured by the trap located at ground level, but this effect was less than expected considering the height difference between the traps. Pollen from woody trees such as Alnus, Betula, Corylus, Fraxinus, Picea, Pinus and Quercus showed a good agreement between the traps in terms of timing and intensity. Similar amounts of pollen were recorded in the two traps when pollen sources were more abundant outside of the city. In contrast, pollen concentrations from Cupressaceae/Taxaceae, Carpinus and Tilia were influenced by nearby pollen sources. The representativeness of both traps for herbaceous pollen depended on the dispersal capacity of the pollen grains, and in the case of Poaceae pollen, nearby pollen sources may influence the pollen content in the air. The timing of the pollen season was similar for both sites; however, the season for some pollen types ended later at ground level probably due to resuspension processes that would favor recirculation of pollen closer to ground level. We believe measurements from the higher station provides a picture of background pollen levels representative of a large area, to which local sources add additional and more variable pollen amounts.

Short-term exposure to pollen and the risk of allergic and asthmatic manifestations: a systematic review and meta-analysis

BACKGROUND

Several studies have assessed effects of short-term exposure to pollen on allergic and asthmatic manifestations. The evidence is inconclusive, and no meta-analysis has been published.

OBJECTIVE

To synthesise the evidence on the relations between short-term pollen exposure and the risk of allergic and asthmatic manifestations.

METHODS

We performed a systematic literature search of PubMed and Scopus databases up to the end of August 2018. In addition, we reviewed the reference lists of relevant articles. Two authors independently evaluated the eligible articles and extracted relevant information in a structured form. We calculated summary effect estimates (EE) based on the study-specific ORs and regression coefficients (β) by applying both fixed-effects and random-effects models.

RESULTS

26 studies met the a priori eligibility criteria, and 12 of them provided sufficient information for the meta-analysis. The summary EE related to 10 grains per m³ increase in pollen exposure showed an 1% increase (EE 1.01, 95% CI 1.00 to 1.02) in the risk of lower respiratory symptoms and a 2% increase (EE 1.02, 95% CI 1.01 to 1.03) in the risk of any allergic or asthmatic symptom. Correspondingly, the risk of upper respiratory symptoms and ocular symptoms increased 7% (EE 1.07, 95% CI 1.04 to 1.09) and 11% (EE 1.11, 95% CI 1.05 to 1.17), respectively, in relation to such pollen exposure. Short-term exposure to pollen did not show any significant effect on daily lung function levels.

CONCLUSION

Our results provide new evidence that short-term pollen exposure significantly increases the risks of allergic and asthmatic symptoms.

Effects of Migration on Allergic Diseases

Studies in migrant populations provide vital opportunities to investigate the role of environmental factors in the pathogenesis of allergic disorders. Differences in allergy prevalence have been observed between migrants and native-born subjects living in the same geographical location. Immigrants who migrate from less affluent countries with lower allergy prevalence tend to have a lower prevalence of allergic disorders compared to native-born residents of the more affluent host country. The patterns of allergic disease prevalence also differ between first- and second-generation migrants. The timing of migration in relation to birth, age at migration, and duration of residence in the host country also influence one's atopic risk. A complex interplay of multiple environmental, socioeconomic, and cultural factors is likely responsible for these observed differences. Further research into the roles of various risk factors in modulating differences in allergic disease prevalence between migrant and native populations will enhance our understanding of the complex gene-environment interactions involved in the pathogenesis of allergic disorders.

Aeroallergens in Canada: Distribution, Public Health Impacts, and Opportunities for Prevention

Aeroallergens occur naturally in the environment and are widely dispersed across Canada, yet their public health implications are not well-understood. This review intends to provide a scientific and public health-oriented perspective on aeroallergens in Canada: their distribution, health impacts, and new developments including the effects of climate change and the potential role of aeroallergens in the development of allergies and asthma. The review also describes anthropogenic effects on plant distribution and diversity, and how aeroallergens interact with other environmental elements, such as air pollution and weather events. Increased understanding of the relationships between aeroallergens and health will enhance our ability to provide accurate information, improve preventive measures and provide timely treatments for affected populations.