Ambient Pollen Research Articles

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.

Contribution of pollen to atmospheric ice nuclei concentrations

Abstract. Recent studies have suggested that the ice-nucleating ability of some types of pollen is derived from non-proteinaceous macromolecules. These macromolecules may become dispersed by the rupturing of the pollen grain during wetting and drying cycles in the atmosphere. If true, this mechanism might prove to be a significant source of ice nuclei (IN) concentrations when pollen is present. Here we test this hypothesis by measuring ambient IN concentrations from the beginning to the end of the 2013 pollen season in Raleigh, North Carolina, USA. Air samples were collected using a swirling aerosol collector twice per week and the solutions were analysed for ice nuclei activity using a droplet freezing assay. Rainwater samples were collected at times when pollen grain number concentrations were near their maximum value and analysed with the drop-freezing assay to compare the potentially enhanced IN concentrations measured near the ground with IN concentrations found aloft. Ambient ice nuclei spectra, defined as the number of ice nuclei per volume of air as a function of temperature, are inferred from the aerosol collector solutions. No general trend was observed between ambient pollen grain counts and observed IN concentrations, suggesting that ice nuclei multiplication via pollen grain rupturing and subsequent release of macromolecules was not prevalent for the pollen types and meteorological conditions typically encountered in the southeastern US. A serendipitously sampled collection after a downpour provided evidence for a rain-induced IN burst with an observed IN concentration of approximately 30 per litre, a 30-fold increase over background concentrations at −20 °C. The onset temperature of freezing for these particles was approximately −12 °C, suggesting that the ice-nucleating particles were biological in origin.

A Case-Crossover Design to Examine the Role of Aeroallergens and Respiratory Viruses on Childhood Asthma Exacerbations Requiring Hospitalization: The Mapcah Study

Background: Few case-control studies of time dependent environmental exposures and respiratory outcomes have been performed. Small sample sizes pose modeling challenges for estimating interactions. In contrast, case cross-over studies are well suited where control selection and responses are low, time consuming and costly. Objective: To demonstrate feasibility in daily recruitment of children admitted to hospital with asthma and validity of the case crossover methodology for hospital based studies. Methods: The Melbourne Air Pollen Children and Adolescent Health (MAPCAH) study recruited incident asthma admissions of children and adolescents aged 2–17 years to a tertiary hospital. A case was defined by date of admission, and eligible cases served as their own controls. We used bi-directional sampling design for control selection. At time of admission, participants underwent skin prick tests and nasal/throat swabs (NTS) to test for respiratory viruses. Questionnaires collected data on asthma management, family history and environmental characteristics. Daily concentrations of ambient pollen, air pollution and weather variables were also available. Results: 644 children were recruited. More than half (63%) were male with mean age 5.2(SD 3.3) years. Non-participants were slightly younger at admission (mean age 4.4, SD 2.8, p<0.001), although the absolute differences were small. Participants and non-participants were well balanced on gender. The most common reason for refusal to participate in the study was “causing further distress to child by skin prick testing”. Gender and age distributions were similar to the overall admissions to the tertiary hospital as well as in Victoria. Our study slightly under-represented winter admissions (p<0.001), and was over-represented in spring (p<0.001). More admissions occurred during the grass pollen season in our study than in general asthma hospital admissions across Victoria (42% versus 22%, p<0.001). Conclusions: The case cross-over method is a highly feasible design for a reasonably sized hospital based study of children with asthma. MAPCAH has robust internal validity and strong generalizability. Collection of data on respiratory viruses and pollen exposure at the time of admission on children with asthma provides important information that will have clinical and public health impacts.

Advances in pediatric asthma in 2012: Moving toward asthma prevention

Last year's "Advances in pediatric asthma: moving forward" concluded the following: "Now is also the time to utilize information recorded in electronic medical records to develop innovative disease management plans that will track asthma over time and enable timely decisions on interventions in order to maintain control that can lead to disease remission and prevention." This year's summary will focus on recent advances in pediatric asthma on modifying disease activity, preventing asthma exacerbations, managing severe asthma, and risk factors for predicting and managing early asthma, as indicated in Journal of Allergy and Clinical Immunology publications in 2012. Recent reports continue to shed light on methods to improve asthma management through steps to assess disease activity, tools to standardize outcome measures in asthma, genetic markers that predict risk for asthma and appropriate treatment, and interventions that alter the early presentation of asthma to prevent progression. We are well on our way to creating a pathway around wellness in asthma care and also to use new tools to predict the risk for asthma and take steps to not only prevent asthma exacerbations but also to prevent the early manifestations of the disease and thus prevent its evolution to severe asthma.

Ambient pollen concentrations and emergency department visits for asthma and wheeze

Previous studies report associations between aeroallergen exposure and asthma exacerbations. Aeroallergen burdens and asthma prevalence are increasing worldwide and are projected to increase further with climate change, highlighting the importance of understanding population-level relationships between ambient pollen concentrations and asthma. We sought to examine short-term associations between ambient concentrations of various pollen taxa and emergency department (ED) visits for asthma and wheeze in the Atlanta metropolitan area between 1993 and 2004. We assessed associations between the 3-day moving average (lag 0-1-2) of Betulaceae (except Alnus species), Cupressaceae, Quercus species, Pinaceae (except Tsuga species), Poaceae, and Ambrosia species pollen concentrations and daily asthma and wheeze ED visit counts, controlling for covarying pollen taxa and ambient pollutant concentrations. We observed a 2% to 3% increase in asthma- and wheeze-related ED visits per SD increase in Quercus species and Poaceae pollen and a 10% to 15% increased risk on days with the highest concentrations (comparing the top 5% of days with the lowest 50% of days). An SD increase in Cupressaceae concentrations was associated with a 1% decrease in ED visits. The association for Quercus species pollen was strongest for children aged 5 to 17 years. Effects of Ambrosia species pollen on asthma exacerbations were difficult to assess in this large-scale temporal analysis because of possible confounding by the steep increase in circulating rhinoviruses every September. Poaceae and Quercus species pollen contribute to asthma morbidity in Atlanta. Altered Quercus species and Poaceae pollen production caused by climate change could affect allergen-induced asthma morbidity in the southeastern United States.

Effects of Ambient Pollen Concentrations on Frequency and Severity of Asthma Symptoms Among Asthmatic Children

Previous studies on the associations between ambient pollen exposures and daily respiratory symptoms have produced inconsistent results. We investigated these relationships in a cohort of asthmatic children using pollen exposure models to estimate individual ambient exposures. Daily symptoms of wheeze, night symptoms, shortness of breath, chest tightness, persistent cough, and rescue medication use were recorded in a cohort of 430 children with asthma (age 4-12 years) in Connecticut, Massachusetts, and New York. Daily ambient exposures to tree, grass, weed, and total pollen were estimated using mixed-effects models. We stratified analyses by use of asthma maintenance medication and sensitization to grass or weed pollens. Separate logistic regression analyses using generalized estimating equations were performed for each symptom outcome and pollen type. We adjusted analyses for maximum daily temperature, maximum 8-hour average ozone, fine particles (PM2.5), season, and antibiotic use. Associations were observed among children sensitized to specific pollens; these associations varied by use of asthma maintenance medication. Exposures to even relatively low levels of weed pollen (6-9 grains/m(3)) were associated with increased shortness of breath, chest tightness, rescue medication use, wheeze, and persistent cough, compared with lower exposure among sensitized children on maintenance medication. Grass pollen exposures ≥ 2 grains/m(3) were associated with wheeze, night symptoms, shortness of breath, and persistent cough compared with lower exposure among sensitized children who did not take maintenance medication. Even low-level pollen exposure was associated with daily asthmatic symptoms.

Pine pollen dehiscence relative to thrips population dynamics

A two-part study related tree pollen dehiscence and thrips population dynamics in the field, and directly evaluated effects of pine pollen deposition on Frankliniella spp. (Thysanoptera: Thripidae) reproduction on tobacco, Nicotiana tabacum L. (Solanaceae), under laboratory conditions. Ambient pollen and thrips were monitored in Tift County, GA, USA, from early spring to late summer/early fall from 2005 to 2008. Correlation analyses were conducted using weekly means of thrips collected on sticky traps compared to weekly pollen counts from a Burkard air sampler and pollen deposition sheets. There were significant positive correlations between pollen and thrips counts on later dates, suggesting that if a relationship exists between pine pollen dehiscence and thrips population dynamics, it will be delayed. Over all years combined, the first spring time peak in Frankliniella fusca (Hinds) counts on sticky traps occurred at 227 accumulated degree days (dd) after the first peak in pine pollen, approximately the dd required to complete a single F. fusca generation. Two subsequent thrips peaks occurred at approximately one and two F. fusca generations following the first peak. After 10 weeks following the final peak in pollen, there appears to be no more effect of pollen on thrips population dynamics. A tobacco leaf, lightly dusted with Slash pine [Pinus elliottii Engelmann (Pinaceae)] pollen to mimic natural deposition, showed a significant increase in the number of offspring produced per Frankliniella occidentalis (Pergande) and F. fusca female. The total offspring produced increased five-fold in F. fusca and 22-fold in F. occidentalis in 15 days on the pollen-treated leaves over the untreated leaves.

Acute Associations Between Ambient Air Pollution and Pediatric Asthma Emergency Department Visits in Atlanta, 1993–2004

ISEE-0463 Background and Objective: We investigated effect modification by season and potential confounding by ambient pollen levels and circulating respiratory infections on short-term associations between ambient air pollutants and pediatric emergency department visits for asthma or wheeze. Methods: Hospital-specific daily counts of emergency room visits for asthma or wheeze among children age 5–17 were collected from 41 Metropolitan Atlanta, USA, hospitals during 1993–2004 (n = 91,386 visits). Three-day moving averages of central monitoring station ambient air pollution measurements were calculated for the criteria gases, PM10, coarse PM, PM2.5, and several PM2.5 components. Risk ratios for the warm season (May-October) and cold season (November-April) were estimated via Poisson generalized linear models so as to approximate a case-crossover analysis (matching on year, month, and lag 0 max temperature in Celsius) while accounting for overdispersion. We included a cubic polynomial for day-of-season; indicator variables for hospital and day of week; the daily count of upper respiratory infections among children age 5–17 (aggregated over hospitals); and three-day moving averages of dew point and minimum temperature. We also investigated confounding by ambient levels of several pollen species. Results: We observed several significant positive associations during the warm season and few associations during the cold season. Ozone in particular was strongly associated with pediatric asthma emergency department visits in both seasons. In multipollutant models we observed evidence for effects of both ozone and traffic pollutants. Ambient pollen levels did not appear to confound these relationships. Risk ratio estimates tended to be closer to unity when we controlled for upper respiratory infections, although associations were present regardless. Conclusion: Although we controlled tightly for temperature and temporal trends, we nevertheless observed several positive, statistically significant associations between ambient pollutants and pediatric emergency department visits for asthma and wheeze.

Evaluating chloroplast DNA in prehistoric Texas coprolites: medicinal, dietary, or ambient ancient DNA?

Molecular analysis of coprolites from Hinds Cave, Texas recovered chloroplast DNA sequences. The sequences were interpreted as evidence of diet. We analyzed 19 Hinds Cave coprolites to evaluate the potential sources of the chloroplast DNA (cpDNA) and compared our results to previous studies. This review shows that some cpDNA sequences could be from well-known prehistoric plants foods. Some other sequences could have come from ambient plant material in the guts of small animals eaten by humans in antiquity. Using pollen concentration analysis, we identify sources of ambient plant material which could have been inhaled or imbibed. It is even possible that cpDNA sequences are from proplastids within ambient pollen grains themselves. However, three sequence types cannot be explained as resulting from only dietary or ambient sources. We suggest instead that these might be from medicinal or hallucinogenic plants. We compared these three sequences to existing sequences in the GenBank. We found that these sequences are 100% matches for Rhamnus, Fouquieria, and Solanum.

Respiratory hospital admissions were associated with ambient airborne pollen in Darwin, Australia, 2004–2005

Although the role of pollen and fungus in specific allergic disorders has been well established, the public health impacts of ambient concentrations of airborne pollen and fungal spores; the shapes of concentration-response relationships; and the relative effects of different taxa are gaps in current knowledge. To investigate associations between daily average ambient pollen and fungal spore concentrations with hospital admissions for total respiratory diseases; asthma; chronic obstructive pulmonary disease (COPD); and respiratory infections in Darwin, Australia, during the period from April 2004 to November 2005. We assessed these relationships in a two-stage modelling approach designed to quantify potential non-linear relationships. First, generalized additive models determined the shapes of concentration-response relationships. Second, linear associations were examined using generalized linear models. Non-linear relationships were analysed by categorizing pollen and fungal spore concentrations based on their distributions. Positive linear associations were found between total pollen concentrations and hospital admissions for total respiratory diseases and COPD. While our exploratory first-stage analysis suggested non-linear relationships for total pollen with asthma and respiratory infections, no convincing evidence for these relationships was found in the second-stage analysis. When individual taxa were investigated, associations were the strongest in relation to Myrtaceae pollen (the dominant tree taxa in the region), while positive associations not attaining statistical significance were observed for Poaceae, Cyperaceae and Arecaceae. No associations were evident for any conditions with fungal spores. Our finding of an association between pollen count and respiratory hospital admissions that could not be explained by asthma admissions suggests that ambient airborne pollens might have a wider public health impact than previously recognized.

Ambient Pollen Levels and Emergency Department Visits for Asthma In Atlanta, Georgia

Ambient Pollen Levels and Emergency Department Visits for Asthma In Atlanta, Georgia

Short-term effects of air pollution on daily asthma emergency room admissions

Many time-series studies have shown positive associations between air pollutants and asthma morbidity. However, few studies have included pollen as a potential confounder when examining this relationship. This study analysed the short-term association between air pollutants (sulphur dioxide (SO2), particles measured with a median aerodynamic diameter of <10 microm (PM10), nitrogen dioxide (NO2) and ozone (O3)) and asthma emergency room admissions in Madrid, Spain, in 1995-1998, adjusting for four types of pollen with allergenic potential (Olea europaea, Plantago sp., Poaceae and Urticaceae). Data were analysed using autoregressive Poisson regression and generalised additive models (GAM). The strongest associations were observed at 1 day lag for O3, and 3 days lag for the remaining pollutants. Using Poisson regression, a single-pollutant model showed that a 10-microg x m(-3) rise in pollutant level led to relative risks of: 1.039 for PM10; 1.029 for SO2; 1.033 for NO2; and 1.045 for O3. Adjustment for the different types of pollen led to no substantial variation in these associations. In the multipollutant models for cold-season pollutants (including PM10, SO2 and the four types of pollen) and photochemical pollutants (including NO2, O3 and the four types of pollen) the associations for PM10, NO2 and O3 held, but no relationship with SO2 was evident. GAM analysis yielded the same results, both in terms of lags and of quantification of the effect for all pollutants. In conclusion, the usual air pollution levels in Madrid were associated with an increase in asthma emergency room admissions, and this association remained controlling for the presence of ambient pollen.

Origin and Distribution of Cr2, a Gene for Resistance to White Pine Blister Rust in Natural Populations of Western White Pine

ABSTRACT The distribution and frequency of the Cr2 gene for resistance to white pine blister rust (Cronartium ribicola) in western white pine (Pinus monticola) was surveyed in natural populations of the host by inoculation of open-pollinated seedlings from 687 individual seed parents from throughout most of the species' range. Because Cr2 is dominant and results in a conspicuous hypersensitive reaction (HR) in pine needles, the phenotype can readily be detected in offspring of susceptible seed parents fertilized by unknown Cr2 donors in the ambient pollen cloud. Gametic frequencies of Cr2 were thus determined as the proportion of total challenged seedlings that were pollen receptors exhibiting the Cr2 phenotype. Zygotic frequencies, the proportion of seed parents with progeny that segregated in Mendelian ratios for the Cr2 phenotype to the total number of parents, were a complementary, though less precise, measure. Cr2 frequency was rare overall, ranging from 0.004 to 0.008 in the Sierra Nevada to about 0.001 in the central Cascade Range; it was undetectable further north in the Cascades, as well as in the Rocky Mountains and Coast Mountains of the United States and Canada. The diminishing frequency of Cr2 from the southern and central Sierra Nevada northward mirrors that of Cr1 in sugar pine (P. lambertiana) and points to this region as the origin of both genes. We rationalize that this coincidence may have resulted from protection that these genes may have conferred on both species to an endemic pine stem rust congeneric with C. ribicola (C. occidentale) in recent geologic epochs.

Supplemental mass pollination success rate in a mature Douglas-fir seed orchard

Supplemental mass pollination (SMP) success rate in a mature Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seed orchard was studied with the aid of a unique electrophoretically detectable allozyme marker. Operational applications, and branch applications that were carried out one, two, or three times, were conducted during the orchard's maximal pollen release (i.e., the height of pollination). No significant increase in seed-yield traits (total number of seeds per cone, number of filled seeds per cone, and seed efficiency) was observed between wind-pollinated and SMP-treated (operational and one and multiple branch visits) cones. However, multiple branch visits (18%) showed significant increase in SMP success rate when compared with the operational visit (8%) or the one branch visit (9%) results. No significant increase in SMP success rate was obtained when the number of branch visits was increased from two (17.8%) to three (17.9%). It was concluded that operational SMP had the potential to improve the genetic value of the treated Douglas-fir crops even under high pollen load. The degree of improvement is dependent directly on SMP fertilization success and indirectly on the genetic value differential between the supplemented and the orchard's ambient pollen, the frequency of application, and the quality of the pollen applied (i.e., viability).

Potential genetic improvement due to supplemental mass pollination management in conifer seed orchards

Enhancement of the genetic value of conifer seeds produced in open-pollinated conifer seed orchards by supplemental mass pollination (SMP) is affected by the timing of the application, orchard flowering phenologies, and background pollen values. Ambient pollen cloud genetic values are often only marginally different from the genetic value of the SMP pollen and the level of improvement is low. Large gains can be made by intensive applications of high genetic quality pollen during periods of low value ambient pollen. The time and expense involved with the intensive application programs needs to be weighed against the potential genetic gains prior to initiating the program.

Distribution and incidence of North American pollen aeroallergens

Using standardized aerosampling procedures, ambient pollen samples were collected at 15 locations in six regions of North America. The results provide baselines for examining human exposure to inhalant pollen allergens throughout the year on a broad geographic scale. In eastern temperate areas, pollen shed was closely linked to plant flowering seasons, with trees releasing pollen in the spring, grasses in the early summer, and weeds in the later summer and fall. Variations to this fundamental pattern were observed to the south and west; understanding these differences is essential if atopic persons suffering from allergic symptoms are to be assisted. For example, highly diverse tree pollen was found in North Carolina and Georgia for prolonged periods at high levels. These data suggest that a more sensitized population in the southeastern United States manifests allergic symptoms longer. Further south and southwest, pollen was captured throughout the year and sometimes at unexpected times. For instance, bimodal releases of grass pollen in both the spring and fall allow dual exposures of atopic persons, extending possible hypersensitivity to multiple seasons. Enhancing pollen exposure further, our data show limited overall variation in morning and afternoon levels, implying a continuous absorption of all major pollen types during daylight hours.

Aeropollen of herbaceous plants at Corpus Christi, Texas

Three major herbaceous groups, the Asteraceae, Amaranthaceael Chenopodiaceae, and Poaceae, shed abundant pollen in coastal southern Texas during late summer to fall. The grasses, and to a lesser extentParthenium (Asteraceae), also release pollen in the spring, giving marked bimodal distributions. These aeropollen patterns were consistent between 1987 and 1989. Although environmental conditions and palynological features are important in understanding aeropollen variabilities, differing inherent photoperiodic response of wind pollinated taxa in the spring and fall, and to a more limited extent during summer and winter, are of primary relevance at Corpus Christi, and indeed elsewhere, in the initiation and cessation of flowering, and thus of the release of ambient pollen. To comprehend photoperiodicity is to understand the fundamental patterns of aeropollen occurrences year after year.

Multivariate analysis of ambient environmental factors and respiratory effects.

Relationships between respiratory health and environmental conditions (pollen, pollution and meteorology) are investigated in 204 subjects in four symptom groups in four geographical clusters in Tucson. Techniques used are principal components, factor and path analysis. Daily respiratory symptoms and peak expiratory flows were recorded during a three-year period. Ambient pollutants, meteorological conditions and pollen types were monitored in or near the clusters. Factor-based scales, which are climate and season specific, are developed for the environmental variables. Three pollutant/meteorological scales represent 'Summer', 'Winter', and 'Humidity'. Four pollen scales represent early and late spring, summer and fall pollen types. Relationships between environmental variables, respiratory symptoms and peak expiratory flow are analyzed with path diagrams, after accounting for age, sex, smoking habits and stove type. The different effects of the environment on asthmatics, allergics and airways obstructive disease subjects have been demonstrated. Many relationships were found between environmental factors and respiratory responses. The pollutant and meteorological variables are related to respiratory symptoms and peak flow directly as well as through interactions with pollen types. Some of the largest positive coefficients are seen in association with seasonal pollen types, specifically, rhinitis and dyspnoea.