Relationship of outdoor air quality to pediatric asthma exacerbations

About the Biodiversity of the Air Microbiome

This brief review focuses on the properties of bioaerosols, presenting some recent results of metagenomic studies of the air microbiome performed using next-generation sequencing. The taxonomic composition and structure of the bioaerosol microbiome may display diurnal and seasonal dynamics and be dependent on meteorological events such as dust storms, showers, fogs, etc., as well as air pollution. The Proteobacteria and Ascomycota members are common dominants in bioaerosols in different troposphere layers. The microbiological composition of the lower troposphere air affects the composition and diversity of the indoor bioaerosol microbiome, and information about the latter is very important, especially during exacerbated epidemiological situations. Few studies focusing on the bioaerosol microbiome of the air above Russia urge intensification of such research.

Outdoor Mold and Respiratory Health: State of Science of Epidemiological Studies

BACKGROUND

Fungal spores are the predominant biological particulates in outdoor air. However, in contrast to pollens or outdoor air pollution, little is known about their respiratory health risks.

OBJECTIVES

The objectives were to conduct the first review of epidemiological studies on the short- and long-term effects of outdoor mold exposure on respiratory health in children and adults.

METHODS

Health outcomes included asthma, lung function, and rhinitis. Cross-sectional and longitudinal epidemiological studies using quantitative measures of outdoor mold exposure (optical microscopy, culture-based methods) were selected, providing that important confounding factors including temporal trends or meteorological factors were accounted for. A systematic literature search was performed up to June 2020, leading to the selection of 37 publications.

RESULTS

Most studies were longitudinal and investigated short-term effects. There is evidence of an association between outdoor fungal exposure and an increase in asthma exacerbation among children for total spores, 2 phyla (ascomycetes, basidiomycetes), and 2 taxa (Cladosporium, Alternaria). A few studies also suggested an association for Coprinus, Ganoderma, Aspergillus-Penicillium, Botrytis, and Epicoccum in children, but this needs to be confirmed. Some studies reported mold associations with rhinitis, lung function, and among adults, but these were few in number or inconsistent.

DISCUSSION

Further ecological studies in different regions that measure exposure to all taxa over several years are required to better understand their impact on rhinitis, asthma exacerbations and lung function. Larger panel studies are necessary to identify threshold effects in susceptible individuals. Finally, further research should assess the long-term effects of outdoor mold.

Associations of air pollution and greenness with mortality in Greece: An ecological study

BACKGROUND

Epidemiological studies have documented the adverse effects of long-term exposure to fine particulate matter (PM_2.5) on health, while there has been less research on the effects of nitrogen dioxide (NO₂), black carbon (BC) and especially ozone (O₃). Furthermore, there is limited evidence for the synergistic effects of exposure to pollutants and greenness. We investigated the association of long-term exposure to air pollution and greenness with natural-cause, cardiovascular and respiratory mortality in Greece using an ecological study design.

METHODS

Mortality and socioeconomic data were obtained from 1035 municipal units from the 2011 census data. Annual average PM_2.5, NO₂, BC and O₃ concentrations for 2010 were derived from 100 × 100 m surfaces predicted by hybrid LUR models. The normalized difference vegetation index was used to assess greenness. We applied Poisson regression models on standardized mortality rates adjusted for socioeconomic indicators and lung cancer rates, accounting for spatial autocorrelation. The analysis was conducted initially for the whole country and then separately for urban and rural areas. We assessed interactions between pollutants and greenness and applied two-exposure models.

RESULTS

An interquartile range (IQR) increase in PM_2.5, NO₂ and BC was associated with increases in natural-cause mortality (Relative Risk (RR) 1.09, 95% confidence interval (CI): 1.08, 1.11; RR 1.03 (95% CI: 1.03, 1.04) and RR 1.02 (95% CI: 1.02, 1.03), respectively), while PM_2.5 and NO₂ were also associated with cause-specific mortality. Greenness was associated with lower natural-cause (RR 0.95, 95% CI: 0.94, 0.96 per IQR) and cause-specific mortality. For all outcomes we estimated a protective association with O₃ (natural-cause mortality RR 0.79, 95% CI: 0.76, 0.82 per IQR). All associations were stronger in urban areas. We estimated negative statistically significant interactions between air pollution and greenness for respiratory morality and positive ones for cardiovascular mortality. Estimates were mostly robust to co-exposure adjustment.

CONCLUSIONS

Our findings support associations of air pollution and greenness with mortality, both in urban and rural areas of Greece. Further research is needed to elaborate on the synergies in cause-specific mortality. Our results on the interactions between pollutants and greenness may imply differential biological mechanisms for cause-specific mortality and warrant further investigation.

Interactive effects of allergens and air pollution on respiratory health: A systematic review

BACKGROUND

Studies have demonstrated an adverse role of outdoor allergens on respiratory symptoms. It is unknown whether this effect is independent or synergistic of outdoor air pollutants.

METHODS

We systematically reviewed all epidemiological studies that examined interaction effects between counts of outdoor airborne allergens (pollen, fungal spores) and air pollutants, on any respiratory health outcome in children and adults. We searched the MEDLINE, EMBASE and Scopus databases. Each study was summarized qualitatively and assessed for quality and risk of bias (International Prospective Register for Systematic Reviews, registration number CRD42020162571).

RESULTS

Thirty-five studies were identified (15 timeseries, eight case-crossovers, 11 panels and one cohort study), of which 12 reported a significant statistical interaction between an allergen and air pollutant. Eight interactions were related to asthma outcomes, including one on lung function measures and wheeze, three to medical consultations for pollinosis and one to allergic symptoms (nasal, ocular or bronchial). There was no consensus as to which allergen or air pollutant is more likely to interact. No study investigated whether interactions are stronger in atopic individuals.

CONCLUSION

Despite strong evidence from small experimental studies in humans, only a third of studies identified significant allergen-pollutant interactions using common epidemiological study designs. Exposure misclassification, failure to examine subgroups at risk, inadequate statistical power or absence of population-level effects are possible explanations.

A novel approach for exposing and sharing clinical data: the Translator Integrated Clinical and Environmental Exposures Service

OBJECTIVE

This study aimed to develop a novel, regulatory-compliant approach for openly exposing integrated clinical and environmental exposures data: the Integrated Clinical and Environmental Exposures Service (ICEES).

MATERIALS AND METHODS

The driving clinical use case for research and development of ICEES was asthma, which is a common disease influenced by hundreds of genes and a plethora of environmental exposures, including exposures to airborne pollutants. We developed a pipeline for integrating clinical data on patients with asthma-like conditions with data on environmental exposures derived from multiple public data sources. The data were integrated at the patient and visit level and used to create de-identified, binned, "integrated feature tables," which were then placed behind an OpenAPI.

RESULTS

Our preliminary evaluation results demonstrate a relationship between exposure to high levels of particulate matter ≤2.5 µm in diameter (PM2.5) and the frequency of emergency department or inpatient visits for respiratory issues. For example, 16.73% of patients with average daily exposure to PM2.5 >9.62 µg/m3 experienced 2 or more emergency department or inpatient visits for respiratory issues in year 2010 compared with 7.93% of patients with lower exposures (n = 23 093).

DISCUSSION

The results validated our overall approach for openly exposing and sharing integrated clinical and environmental exposures data. We plan to iteratively refine and expand ICEES by including additional years of data, feature variables, and disease cohorts.

CONCLUSIONS

We believe that ICEES will serve as a regulatory-compliant model and approach for promoting open access to and sharing of integrated clinical and environmental exposures data.

Summer storms and their effects on the spectrum and quantity of airborne bioparticles in Bratislava, Central Europe

A thunderstorm is a risk factor for severe respiratory allergy or asthma attacks in patients suffering from pollen/spore allergy. This study aimed to investigate the changes in the spectrum and quantity of pollen and fungal spores in the air of Bratislava during summer storms as well as the impact of selected environmental parameters on these changes. Pollen/spore samples were collected using a Burkard volumetric aerospore trap during summer 2016. To identify those types of pollen/spores that may harm human health during the storm episodes, we analysed how the concentration of individual bioparticles in the air changed during pre-storm/storm/post-storm periods. The effect of environmental variables on the concentration of selected pollen/spore types was evaluated through Spearman's correlation analysis. The results of our study suggest that thunderstorm-related respiratory allergy symptoms in the study area may be caused by (1) spores of Myxomycetes, the airborne concentration of which increases due to an increase in wind speed during the pre-storm period; (2) ruptured pollen and Diatripaceae spores, the concentration of which increases due to increase in precipitation and relative air humidity, respectively, during the storm period; and (3) spores of Fusarium and Leptosphaeria, the concentration of which increases due to increase in precipitation and air temperature, respectively, during the post-storm period.

Interactions between Ambient Air Particles and Greenness on Cause-specific Mortality in Seven Korean Metropolitan Cities, 2008-2016

This study aims to investigate the association of particulate matter with an aerodynamic diameter smaller than 10 μm (PM₁₀) and greenness with cause-specific mortality and their interactions in seven Korean metropolitan cities. We obtained the annual standardized cause-specific mortality rates, annual mean concentration of PM₁₀, and annual Normalized Difference Vegetation Index (NDVI) for 73 districts for the period 2008-2016. We used negative binomial regression with city-specific random effects to estimate the association of PM₁₀ and greenness with mortality. The models were adjusted for potential confounders and spatial autocorrelation. We also conducted stratified analyses to investigate whether the association between PM₁₀ and mortality differs by the level of greenness. Our findings suggest an increased risk of all causes examined, except respiratory disease mortality, with high levels of PM₁₀ and decreased risk of cardiovascular-related mortality with a high level of greenness. In the stratified analyses, we found interactions between PM₁₀ and greenness, but these interactions in the opposite direction depend on the cause of death. The effects of PM₁₀ on cardiovascular-related mortality were attenuated in greener areas, whereas the effects of PM₁₀ on non-accidental mortality were attenuated in less green areas. Further studies are needed to explore the underlying mechanisms.

Indoor particulate matter and lung function in children

People generally spend more time indoors than outdoors resulting in a higher proportion of exposure to particulate matter (PM) occurring indoors. Consequently, indoor PM levels, in contrast to outdoor PM levels, may have a stronger relationship with lung function. To test this hypothesis, indoor and outdoor PM_2.5 and fungal spore data were simultaneously collected from the homes of forty-four asthmatic children aged 10-16 years. An optical absorption technique was utilized on the collected PM_2.5 mass to obtain concentrations of black carbon (BC) and ultraviolet light absorbing particulate matter, (UVPM; a marker of light absorbing PM_2.5 emitted from smoldering organics). Enrolled children completed spirometry after environmental measurements were made. Given the high correlation between PM_2.5, BC, and UVPM, principal component analysis was used to obtain uncorrelated summaries of the measured PM. Separate linear mixed-effect models were developed to estimate the association between principal components of the PM variables and spirometry values, as well as the uncorrelated original PM variables and spirometry values. A one-unit increase in the first principal component variable representing indoor PM (predominantly composed of UVPM and PM_2.5) was associated with 4.1% decrease (99% CI = -6.9, -1.4) in FEV₁/FVC ratio. 11.3 μg/m³ increase in indoor UVPM was associated with 6.4% and 14.7% decrease (99% CI = -10.4, -2.4 and 99% CI = -26.3, -2.9, respectively) in percent predicted FEV₁/FVC ratio and FEF_25-75 respectively. Additionally, 17.7 μg/m³ increase in indoor PM_2.5 was associated with 6.1% and 12.9% decrease (99% CI = -10.2, -1.9 and 99% CI = -24.9, -1.0, respectively) in percent predicted FEV₁/FVC ratio and FEF_25-75, respectively. Outdoor PM, indoor BC, and indoor fungal spores were not significantly associated with lung function. The results indicate that indoor PM is more strongly associated with lung function in children with asthma as compared with outdoor PM.

Asthma Prevalence Among Medicaid-Enrolled Children

BACKGROUND

Small-area asthma prevalence measures, which are crucial for targeting interventions, are currently sparsely available for children.

OBJECTIVE

To provide measures of in-contact asthma prevalence for the 2012 Medicaid child population so as to highlight areas in need of targeted asthma interventions.

METHODS

Using the 2012 Medicaid Analytic eXtract claims files, we developed 2 prevalence metrics differentiated by persistent and diagnosed asthma. We developed prevalence measures at the state, county, and census tract levels, with statistical inferences to highlight areas of high prevalence where interventions should be focused. We compared the measures with asthma prevalence estimates derived from a sample of the child population that self-reported whether they have been diagnosed with asthma regardless of in-contact asthma.

RESULTS

A total of 1.98 million (8.1%) and 1.71 million (6.9%) Medicaid-enrolled children were identified with in-contact asthma diagnosis and persistent asthma, respectively. Among 40 states, 17 had lower prevalence estimates for the Medicaid-enrolled children compared with similar child asthma self-reported prevalence estimates from the Centers for Disease Control and Prevention. High-prevalence regions spanned primarily in the southern Midwest region, from Texas to West Virginia and from Illinois to north Florida.

CONCLUSION

There are large variations in the differences between the self-reported estimates from the Centers for Disease Control and Prevention for the general population and the in-contact estimates for the Medicaid-enrolled children, highlighting potential asthma misdiagnosis in the Medicaid population in many states. Small-area estimates point to areas of high prevalence, consistently throughout the south and southeast.

Aeroallergens in North-Central Nigeria

INTRODUCTION AND OBJECTIVES

Aeroallergens are airborne organic substances which are responsible for allergenic diseases in hypersensitive individuals. People are exposed to their allergens either directly or after their entrance into the interiors. The spatio-temporal pattern of aeroallergens and their relationship with weather variability in Abuja and Nassarawa, North-Central Nigeria was studied.

MATERIALS AND METHODS

Aerosamples were trapped with modified Tauber-like pollen traps. Samples were collected monthly and centrifuged at 2500rpm for 5 min and subjected to acetolysis. Meteorological data were collected from the Nigerian Meteorological Agency.

RESULTS AND CONCLUSION

Aeroallergens concentration were unequivocally regulated by weather variables in both locations, indicating the possible use of aeroallergens especially pollen and spores as bio-indicators of weather variations and change. Aeroallergens encountered were fungal spores, pollen, diatom frustules, fern spores, algal cyst/cells in decreasing order of dominance. Among pollen group, Poaceae, Amarathaceae/Chenopodiaceae and Hymenocardia acida dominated. Spores of Smut species, Puccinia, Curvularia and Nigrospora were major contributors among aeromycoflora. Fungal spores morphotype dominated during the rainier months and were major contributors of the aeroallergen spectrum with those belonging to Deuteromycete preponderant. Aeroallergens which were previously identified as triggers of conjunctivitis, asthma, allergic sinusitis and bronchopulmonary allergic diseases were frequently present in both locations. Pollen prevailed more during the harmattan, influenced by northeast trade wind. Pollen component differed and was based on autochthonous source plants, indicating difference in sub-vegetational types.

Outdoor pollen is a trigger of child and adolescent asthma emergency department presentations: A systematic review and meta-analysis

BACKGROUND

In the context of increased asthma exacerbations associated with climatic changes such as thunderstorm asthma, interest in establishing the link between pollen exposure and asthma hospital admissions has intensified. Here, we systematically reviewed and performed a meta-analysis of studies on pollen and emergency department (ED) attendance.

METHODS

A search for studies with appropriate search strategy in MEDLINE, EMBASE, Web of Science and CINAHL was conducted. Each study was assessed for quality and risk of bias. The available evidence was summarized both qualitatively and meta-analysed using random-effects models when moderate heterogeneity was observed.

RESULTS

Fourteen studies were included. The pollen taxa investigated differed between studies, allowing meta-analysis only of the effect of grass pollen. A statistically significant increase in the percentage change in the mean number of asthma ED presentations (MPC) (pooled results from 3 studies) was observed for an increase in 10 grass pollen grains per cubic metre of exposure 1.88% (95% CI = 0.94%, 2.82%). Time series studies showed positive correlations between pollen concentrations and ED presentations. Age-stratified studies found strongest associations in children aged 5-17 years old.

CONCLUSION

Exposure to ambient grass pollen is an important trigger for childhood asthma exacerbations requiring ED attendance. As pollen exposure is increasingly a problem especially in relation to thunderstorm asthma, studies with uniform measures of pollen and similar analytical methods are necessary to fully understand its impact on human health.

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.

Interventions for autumn exacerbations of asthma in children

BACKGROUND

Asthma exacerbations in school-aged children peak in autumn, shortly after children return to school following the summer holiday. This might reflect a combination of risk factors, including poor treatment adherence, increased allergen and viral exposure, and altered immune tolerance. Since this peak is predictable, interventions targeting modifiable risk factors might reduce exacerbation-associated morbidity and strain upon health resources. The peak occurs in September in the Northern Hemisphere and in February in the Southern Hemisphere.

OBJECTIVES

To assess the effects of pharmacotherapy and behavioural interventions enacted in anticipation of school return during autumn that are designed to reduce asthma exacerbations in children during this period.

SEARCH METHODS

We searched the Cochrane Airways Group Trials Register, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform, reference lists of primary studies and existing reviews, and manufacturers' trial registries (Merck, Novartis and Ono Parmaceuticals). We searched databases from their inception to 1 December 2017, and imposed no restriction on language of publication.

SELECTION CRITERIA

We included all randomised controlled trials comparing interventions aimed specifically at reducing autumn exacerbations with usual care, (no systematic change in management in preparation for school return). We included studies providing data on children aged 18 years or younger.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently screened records identified by the search and then extracted data and assessed bias for trials meeting the inclusion criteria. A third review author checked for accuracy and mediated consensus on disagreements. The primary outcome was proportion of children experiencing one or more asthma exacerbations requiring hospitalisation or oral corticosteroids during the autumn period.

MAIN RESULTS

Our searches returned 546 trials, of which five met our inclusion criteria. These studies randomised 14,252 children to receive either an intervention or usual care. All studies were conducted in the Northern Hemisphere. Three interventions used a leukotriene receptor antagonist, one used omalizumab or a boost of inhaled corticosteroids, and the largest study, (12,179 children), used a medication reminder letter. Whilst the risk of bias within individual studies was generally low, we downgraded the evidence quality due to imprecision associated with low participant numbers, poor consistency between studies, and indirect outcome ascertainment.A US study of 513 children with mild/severe asthma and allergic sensitisation was the only study to provide data for our primary outcome. In this study, the proportion of participants experiencing an exacerbation requiring oral corticosteroids or hospital admission in the 90 days after school return was significantly reduced to 11.3% in those receiving omalizumab compared to 21.0% in those receiving placebo (odds ratio 0.48, 95% confidence interval 0.25 to 0.92, moderate-quality evidence). The remaining studies used alternative exacerbation definitions. When data from two leukotriene receptor antagonist studies with comparable outcomes were combined in a random-effects model, there was no evidence of an effect upon exacerbations. There was no evidence that a seasonal medication reminder letter decreased unscheduled contacts for a respiratory diagnosis between September and December.Four studies recorded adverse events. There was no evidence that the proportion of participants experiencing at least one adverse event differed between intervention and usual care groups. Lack of data prevented planned subgroup and sensitivity analyses.

AUTHORS' CONCLUSIONS

Seasonal omalizumab treatment from four to six weeks before school return might reduce autumn asthma exacerbations. We found no evidence that this strategy is associated with increased adverse effects other than injection site pain, but it is costly. There were no data upon which to judge the effect of this or other seasonal interventions on asthma control, quality of life, or asthma-related death. In future studies definitions of exacerbations should be provided, and standardised where possible. To investigate possible differential effects according to subgroup, participants in future trials should be well characterised with respect to baseline asthma severity and exacerbation history in addition to age and gender.

[Outdoor moulds and respiratory health]

Mould spores constitute the largest portion of biologic particulate matter suspended in the outdoor atmosphere. There is no universal method for collecting airborne mould spores. The most used sampler, Hirst's apparatus, operates continuously and gives results in individual spores per cubic metre of air. Spore concentrations depend on available substrates, human activities such as agriculture, season, diurnal meteorological variations and climate changes. Under natural conditions, concentrations of over 100,000 spores per cubic metre are not exceptional. Cladosporium is the most commonly identified outdoor mould. The association between respiratory health and outdoor mould spore exposure has been assessed in clinical studies, and also by cross-sectional, and less often longitudinal, epidemiological studies. The relationship between asthma exacerbations and specific mould spores has been demonstrated in longitudinal studies. Cross sectional studies have related measurements of mould spore concentrations to severity of bronchial symptoms, drug consumption and peak-flow measurements in groups of asthmatic subjects. Ecological time-series studies use daily indicators of asthma exacerbations (emergency room visits, hospitalizations) within the general population. The moulds mainly incriminated are Cladosporium and Alternaria. They are associated with seasonal, but also perennial, asthma and rhinitis. Further studies are needed to better assess the impact of outdoor moulds on health, particularly basidiomycetes. Studies with molecular biology tools are probably a way forward.

The role of outdoor fungi on asthma hospital admissions in children and adolescents: A 5-year time stratified case-crossover analysis

BACKGROUND

Some fungal spores can trigger asthma exacerbation but knowledge of which outdoor fungal spores contribute to asthma hospitalisation is limited.

OBJECTIVES

To examine the role of outdoor fungal spores in child and adolescent asthma hospitalisations.

METHODS

We conducted a bi-directional time-stratified case-crossover study of child and adolescent asthma hospitalisations over 5 years. Conditional logistic regression assessed the role of 20 fungi taxa (Same day [L0] and lagged [L1-3]) adjusted for maximum temperature, humidity and grass pollen. Strata specific effects were explored if there was evidence of effect modification by age, sex, air pollutants or grass pollen. Non-linear effects examined with Generalized Additive Models.

RESULTS

Of 2098 children hospitalised for asthma, 60% were boys; mean age was 5.5±3.7 years. Fungal spore counts peaked during warm months. Regression models found weak associations with Coprinus [L0,L1: OR=1.03, 1.01-1.06], Periconia [L0: OR=1.03, 1.001-1.07] and Chaetomium [L2: OR=1.08, 1.0-1.2]. Sex appeared to act as an effect modifier with girls having stronger associations with Cladosporium, Coprinus and total fungi. Older adolescent (14-18 years) hospitalisation was significantly associated with Coprinus and Ustilago/smuts. Air pollutants and grass pollen did not appear to act as effect modifiers. Non-linearity was not detected.

CONCLUSION

There may be associations between some outdoor fungal spores and asthma hospitalisations. Further research needed to explore whether these findings can be replicated; and examine whether fungal sensitisation and/or human rhinovirus infections are associated with stronger effects. If findings are replicated, then the need to develop predictive models for fungal spore distribution and levels may become more important.

The relationship between birch pollen, air pollution and weather types and their effect on antihistamine purchase in two Swedish cities

Exposure to elevated air pollution levels can aggravate pollen allergy symptoms. The aim of this study was to investigate the relationships between airborne birch (Betula) pollen, urban air pollutants NO₂, O₃ and PM₁₀ and their effects on antihistamine demand in Gothenburg and Malmö, Sweden, 2006-2012. Further, the influence of large-scale weather pattern on pollen-/pollution-related risk, using Lamb weather types (LWTs), was analysed. Daily LWTs were obtained by comparing the atmospheric pressure over a 16-point grid system over southern Sweden (scale ~3000 km). They include two non-directional types, cyclonic (C) and anticyclonic (A) and eight directional types depending on the wind direction (N, NE, E…). Birch pollen levels were exceptionally high under LWTs E and SE in both cities. Furthermore, LWTs with dry and moderately calm meteorological character (A, NE, E, SE) were associated with strongly elevated air pollution (NO₂ and PM₁₀) in Gothenburg. For most weather situations in both cities, simultaneously high birch pollen together with high air pollution had larger over-the-counter (OTC) sales of antihistamines than situations with high birch pollen alone. LWTs NE, E, SE and S had the highest OTC sales in both cities. In Gothenburg, the city with a higher load of both birch pollen and air pollution, the higher OTC sales were especially obvious and indicate an increased effect on allergic symptoms from air pollution. Furthermore, Gothenburg LWTs A, NE, E and SE were associated with high pollen and air pollution levels and thus classified as high-risk weather types. In Malmö, corresponding high-risk LWTs were NE, E, SE and S. Furthermore, occurrence of high pollen and air pollutants as well as OTC sales correlated strongly with vapour pressure deficit and temperature in Gothenburg (much less so in Malmö). This provides evidence that the combination of meteorological properties associated with LWTs can explain high levels of birch pollen and air pollution. Our study shows that LWTs represent a useful tool for integrated daily air quality forecasting/warning.

Molecular approaches for the detection and monitoring of microbial communities in bioaerosols: A review

Bioaerosols significantly affect atmospheric processes while they undergo long-range vertical and horizontal transport and influence atmospheric chemistry and physics and climate change. Accumulating evidence suggests that exposure to bioaerosols may cause adverse health effects, including severe disease. Studies of bioaerosols have primarily focused on their chemical composition and largely neglected their biological composition and the negative effects of biological composition on ecosystems and human health. Here, current molecular methods for the identification, quantification, and distribution of bioaerosol agents are reviewed. Modern developments in environmental microbiology technology would be favorable in elucidation of microbial temporal and spatial distribution in the atmosphere at high resolution. In addition, these provide additional supports for growing evidence that microbial diversity or composition in the bioaerosol is an indispensable environmental aspect linking with public health.

Exposure to ambient bioaerosols is associated with allergic skin diseases in Greater Taipei residents

Allergic skin diseases may result from various types of chemical and biological allergens. This study investigated the association between ambient bioaerosol exposure and allergic skin diseases by using the exposure data obtained from land use regression models and interpolated data. Data on daily average outpatient visits for atopic dermatitis (ICD-9-CM 691.8) and contact dermatitis and other eczema (ICD-9-CM 692.9) between November 2011 and August 2012 were obtained from the National Health Insurance Research Database. A generalized estimating equation was used to analyze the associations between the skin diseases and ambient bioaerosol levels. The results indicated that during the study period, contact dermatitis and other eczema were more prevalent than atopic dermatitis in the study area. Most cases were observed in districts of Taipei City and 3 major districts of New Taipei City, namely Xinzhuang, Banqiao, and Xindian. In univariate analysis, most bioaerosols were positively associated with both skin diseases. After adjustment for air pollution and sociodemographic factors, exposure to total fungal spores was significantly associated with atopic dermatitis in males (relative risk [RR] = 1.12; 95% confidence interval [CI] = 1.05-1.19). Contact dermatitis and other eczema had significant relationships with Cladosporium in males (RR = 1.07; 95% CI = 1.02-1.14) and with Aspergillus/Penicillium in females (RR = 1.04; 95% CI = 1.02-1.07). Meteorological parameters, namely wind speed, temperature, and rainfall, were also significantly associated with skin diseases. Our findings reveal that exposure to ambient bioaerosols is a significant and independent risk factor for allergic skin diseases.

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.

Health Outcomes of Exposure to Biological and Chemical Components of Inhalable and Respirable Particulate Matter

Particulate matter (PM) is a key indicator of air pollution and a significant risk factor for adverse health outcomes in humans. PM is not a self-contained pollutant but a mixture of different compounds including chemical and biological fractions. While several reviews have focused on the chemical components of PM and associated health effects, there is a dearth of review studies that holistically examine the role of biological and chemical components of inhalable and respirable PM in disease causation. A literature search using various search engines and (or) keywords was done. Articles selected for review were chosen following predefined criteria, to extract and analyze data. The results show that the biological and chemical components of inhalable and respirable PM play a significant role in the burden of health effects attributed to PM. These health outcomes include low birth weight, emergency room visit, hospital admission, respiratory and pulmonary diseases, cardiovascular disease, cancer, non-communicable diseases, and premature death, among others. This review justifies the importance of each or synergistic effects of the biological and chemical constituents of PM on health. It also provides information that informs policy on the establishment of exposure limits for PM composition metrics rather than the existing exposure limits of the total mass of PM. This will allow for more effective management strategies for improving outdoor air quality.

Weather elements, chemical air pollutants and airborne pollen influencing asthma emergency room visits in Szeged, Hungary: performance of two objective weather classifications

Weather classification approaches may be useful tools in modelling the occurrence of respiratory diseases. The aim of the study is to compare the performance of an objectively defined weather classification and the Spatial Synoptic Classification (SSC) in classifying emergency department (ED) visits for acute asthma depending from weather, air pollutants, and airborne pollen variables for Szeged, Hungary, for the 9-year period 1999-2007. The research is performed for three different pollen-related periods of the year and the annual data set. According to age and gender, nine patient categories, eight meteorological variables, seven chemical air pollutants, and two pollen categories were used. In general, partly dry and cold air and partly warm and humid air aggravate substantially the symptoms of asthmatics. Our major findings are consistent with this establishment. Namely, for the objectively defined weather types favourable conditions for asthma ER visits occur when an anticyclonic ridge weather situation happens with near extreme temperature and humidity parameters. Accordingly, the SSC weather types facilitate aggravating asthmatic conditions if warm or cool weather occur with high humidity in both cases. Favourable conditions for asthma attacks are confirmed in the extreme seasons when atmospheric stability contributes to enrichment of air pollutants. The total efficiency of the two classification approaches is similar in spite of the fact that the methodology for derivation of the individual types within the two classification approaches is completely different.

Outdoor fungi and child asthma health service attendances

Asthma is a significant global public health issue. Severe asthma exacerbations can be triggered by environmental factors and require medical care from health services. Although it is known that fungal exposure may lead to allergic sensitization, little is understood about its impact on asthma exacerbations. This review aims to examine whether outdoor fungi play a significant role in child asthma exacerbations. Systematic search of seven electronic databases and hand searching for peer-reviewed studies published in English, up to 31 August 2013. Inclusion criteria were study population aged <18 yr, diagnosis of asthma, attended a health service; outdoor fungi exposure was reported. Quality and risk of bias assessments were conducted. Due to significant heterogeneity, meta-analysis was not conducted. Of the 1896 articles found, 15 were eligible. Findings were not consistent, possibly due to methodological variations in exposure classifications, statistical methods and inclusion of confounders. Cross-sectional studies found no or weak associations. All but one time series studies indicated an association that varied between fungal species. Increasing evidence indicates that asthmatic children are susceptible to asthma exacerbations when exposed to outdoor fungal spores. There is limited understanding of the contributions of different fungal species. Research is needed to investigate interactions of outdoor fungi with pollen, air pollutants and respiratory viruses.

A systematic review of validated methods to capture acute bronchospasm using administrative or claims data

PURPOSE

To identify and assess billing, procedural, or diagnosis code, or pharmacy claim-based algorithms used to identify acute bronchospasm in administrative and claims databases.

METHODS

We searched the MEDLINE database from 1991 to September 2012 using controlled vocabulary and key terms related to bronchospasm, wheeze and acute asthma. We also searched the reference lists of included studies. Two investigators independently assessed the full text of studies against pre-determined inclusion criteria. Two reviewers independently extracted data regarding participant and algorithm characteristics.

RESULTS

Our searches identified 677 citations of which 38 met our inclusion criteria. In these 38 studies, the most commonly used ICD-9 code was 493.x. Only 3 studies reported any validation methods for the identification of bronchospasm, wheeze or acute asthma in administrative and claims databases; all were among pediatric populations and only 2 offered any validation statistics. Some of the outcome definitions utilized were heterogeneous and included other disease based diagnoses, such as bronchiolitis and pneumonia, which are typically of an infectious etiology. One study offered the validation of algorithms utilizing Emergency Department triage chief complaint codes to diagnose acute asthma exacerbations with ICD-9 786.07 (wheezing) revealing the highest sensitivity (56%), specificity (97%), PPV (93.5%) and NPV (76%).

CONCLUSIONS

There is a paucity of studies reporting rigorous methods to validate algorithms for the identification of bronchospasm in administrative data. The scant validated data available are limited in their generalizability to broad-based populations.

Associations between ozone, PM2.5, and four pollen types on emergency department pediatric asthma events during the warm season in New Jersey: a case-crossover study

BACKGROUND

Asthma is one of the most common chronic diseases among school-aged children in the United States. Environmental respiratory irritants exacerbate asthma among children. Understanding the impact of a variety of known and biologically plausible environmental irritants and triggers among children in New Jersey - ozone, fine particulate matter (PM2.5), tree pollen, weed pollen, grass pollen and ragweed - would allow for informed public health interventions.

METHODS

Time-stratified case-crossover design was used to study the transient impact of ozone, PM2.5 and pollen on the acute onset of pediatric asthma. Daily emergency department visits were obtained for children aged 3-17 years with a primary diagnosis of asthma during the warm season (April through September), 2004-2007 (inclusive). Bi-directional control sampling was used to select two control periods for each case for a total of 65,562 inclusion days. Since the period of exposure prior to emergency department visit may be the most clinically relevant, lag exposures were investigated (same day (lag0), 1, 2, 3, 4, and 5 as well as 3-day and 5-day moving averages). Multivariable conditional logistic regression controlling for holiday, school-in-session indicator, and 3-day moving average for temperature and relative humidity was used to examine the associations. Odds ratios are based on interquartile range (IQR) increases or 10 unit increases when IQR ranges were narrow. Single-pollutant models as well as multipollutant models were examined. Stratification on gender, race, ethnicity and socioeconomic status was explored.

RESULTS

The associations with ozone and PM2.5 were strongest on the same day (lag0) of the emergency department visit (RR IQR=1.05, 95% CI 1.04-1.06) and (RR IQR=1.03, 95% CI 1.02-1.04), respectively, with a decreasing lag effect. Tree and weed pollen were associated with pediatric ED visits; the largest magnitudes of association was with the 5-day average (RR IQR=1.23, 95% CI 1.21-1.25) and (RR 10=1.13, 95% CI 1.12-1.14), respectively. Grass pollen was only minimally associated with the outcome while ragweed had a negative association.

CONCLUSIONS

The ambient air pollutant ozone is associated with increases in pediatric emergency department asthma visits during the warm weather season. The different pollen types showed different associations with the outcome. High levels of tree pollen appear to be an important risk factor in asthma exacerbations.

Interactions of physical, chemical, and biological weather calling for an integrated approach to assessment, forecasting, and communication of air quality

This article reviews interactions and health impacts of physical, chemical, and biological weather. Interactions and synergistic effects between the three types of weather call for integrated assessment, forecasting, and communication of air quality. Today's air quality legislation falls short of addressing air quality degradation by biological weather, despite increasing evidence for the feasibility of both mitigation and adaptation policy options. In comparison with the existing capabilities for physical and chemical weather, the monitoring of biological weather is lacking stable operational agreements and resources. Furthermore, integrated effects of physical, chemical, and biological weather suggest a critical review of air quality management practices. Additional research is required to improve the coupled modeling of physical, chemical, and biological weather as well as the assessment and communication of integrated air quality. Findings from several recent COST Actions underline the importance of an increased dialog between scientists from the fields of meteorology, air quality, aerobiology, health, and policy makers.

The role of seasonal grass pollen on childhood asthma emergency department presentations

BACKGROUND

Few studies have focused on the role of grass pollen on asthma emergency department (ED) presentations among children. None have examined whether a dose-response effect exists between grass pollen levels and these asthma exacerbations.

OBJECTIVES

To examine the association between increasing ambient levels of grass pollen and asthma ED presentations in children. To determine whether these associations are seen only after a thunderstorm, or whether grass pollen levels have a consistent influence on childhood asthma ED visits during the season.

METHODS

A short time series ecological study was conducted for asthma presentations to ED among children in Melbourne, Victoria, and grass pollen, meteorological and air quality measurements recorded during the selected 2003 period. A semi-parametric Poisson regression model was used to examine dose-response associations between daily grass pollen levels and mean daily ED attendance for asthma.

RESULTS

A smoothed plot suggested a dose-response association. As ambient grass pollen increased to about 19 grains/m(3) , the same day risk of childhood ED presentations also increased linearly (P < 0.001). Grass pollen levels were also associated with an increased risk in asthma ED presentations on the following day (lag 1, P < 0.001).

CONCLUSION

This is the first study to establish a clear relationship between increased risk of childhood asthma ED attendance and levels of ambient grass pollen below 20 grains/m(3) , independent of any impact of thunderstorm-associated asthma. These findings have important implications for patient care, such as asthma management programs that notify the general public regarding periods of high grass pollen exposure, as well as defining the timing of initiation of pollen immunotherapy.

Ambient pollen concentrations and emergency department visits for asthma and wheeze

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

Even low-level pollen exposure was associated with daily asthmatic symptoms.

The association of tree pollen concentration peaks and allergy medication sales in new york city: 2003-2008

The impact of pollen exposure on population allergic illness is poorly characterized. We explore the association of tree pollen and over-the-counter daily allergy medication sales in the New York City metropolitan area. Dates of peak tree pollen (maple, oak, and birch) concentrations were identified from 2003 to 2008. Daily allergy medication sales reported to the city health department were analyzed as a function of the same-day and lagged tree pollen peak indicators, adjusting for season, year, temperature, and day of week. Significant associations were found between tree pollen peaks and allergy medication sales, with the strongest association at 2-day lag (excess sales of 28.7% (95% CI: 17.4-41.2) over the average sales during the study period). The cumulative effect over the 7-day period on and after the tree pollen peak dates was estimated to be 141.1% (95% CI: 79.4-224.1). In conclusion, tree pollen concentration peaks were followed by large increases in over-the-counter allergy medication sales.

Associations between atmospheric concentrations of spores and emergency department visits for asthma among children living in Montreal

The authors carried out a time-series study to determine whether short-term increases in the concentrations of spores were associated with emergency department visits from asthma among children 0 to 9 years of age in Montreal, 1994-2004. Concentrations of spores were obtained from one sampling monitor. The authors used parametric Poisson models to model the association between daily admissions to emergency rooms for asthma and ambient exposures to a variety of spores, adjusting for secular trends, changes in weather, and chemical pollutants. For first admissions and exposures to Basidiomycetes, the authors found positive associations at all lags but the concurrent day. For Deuteromycetes and Cladosporium, risks were positive starting at lag 3 days and diminished at lag 6 days. There was little evidence of associations for readmissions, except for Basidiomycetes. The results indicate that Basidiomycetes and Cladosporium spores may be implicated in the exacerbation of asthma among children, most notably in the case of first-time visits to emergency departments, and that the effects appear to be delayed by several days.

Adult asthma exacerbations and environmental triggers: a retrospective review of ED visits using an electronic medical record

BACKGROUND

Despite familiarity with triggers for asthma, there is little recent study on the association of triggers with the emergency department (ED) presentation of adult asthma exacerbation.

METHODS

Retrospective electronic chart review of adult patients treated in an urban teaching hospital ED with chief complaint and diagnostic coding related to asthma and upper respiratory tract infection (URI) was conducted. Monthly aeroallergen data and environmental conditions were obtained from a local allergen extract laboratory and local government sources. Data analysis was performed using Newey-West time series regression modeling with adjustment for autocorrelation or ordinary least squares linear regression modeling using outcome variables of asthma visits and admissions.

RESULTS

There were 56, 747 visits, with 554 asthma visits and 1,514 URI visits. Asthma visits (R(2) = 0.631) were positively correlated with tree pollen counts (correlation coefficient = 0.458 [0.152-0.765]) and average humidity (correlation coefficient = 1.528 [0.296-2.760]). Asthma admissions (R(2) = 0.480) were negatively correlated with average temperature (correlation coefficient = -0.557 [-1.052 to -0.061]) when adjusting for confounding by fine particulate matter.

CONCLUSIONS

The ED acute asthma exacerbation presentation is positively correlated with tree pollen and humidity, whereas need for admission is associated with dropping temperatures. These results reinforce the need for vigilance during periods of increased risk and perhaps focused preventative strategies.

Hospital admissions for respiratory conditions in children and outdoor air pollution in Southwest Milan, Italy

AIM

To evaluate whether a relationship exists in hospital admissions for respiratory conditions in children with outdoor pollution in the Southwest Milan, Italy.

METHODS

Daily count of hospital admissions for asthma, upper or lower respiratory diseases (LRD) occurred among children aged < or =14 years at the San Paolo Hospital during 2007-2008 was recorded. Pollutants included the particular matter of <10 microm diameter, ozone, carbon monoxide (CO) and nitrogen dioxide (NO(2)), reported on the same day of admission and 1 up to 5 days before admission. The moving weekly average (MWA) was also considered.

RESULTS

Total respiratory admissions were associated with the same day level of CO (30.6% increase per 1 mg/m(3) increase, 95% confidence interval, 3.9-69.9%) and with the MWA of NO(2) (9.0% increase per 10 microg/m(3) increase, 1.2-16.8%). The effect of CO was stronger on upper respiratory diseases (URD) (lag 0, 21.3% increase, 6.4-38.3%). The effect of NO(2) was stronger on LRD (MWA, 5.3% increase, 0.9-10.2%). Multipollutant models confirmed the role of CO on URD and that of NO(2) on LRD.

CONCLUSION

Carbon monoxide and nitrogen dioxide may be associated with emergency hospital admissions for respiratory conditions among children in Southwest Milan.

Influence of season and temperature on the relationship of elemental carbon air pollution to pediatric asthma emergency room visits

Previous studies have demonstrated an association between air pollution and asthma exacerbation. Less understood is the effect of elemental carbon (EC), and the interaction of EC with temperature, on increases in pediatric asthma emergency department visits and how these relationships change across the seasons in a metropolitan area with several industries and relatively low air pollution. Measurements of EC, ozone (O(3)), sulfur dioxide (SO(2)), and total oxides of nitrogen (NO(x)) were available from the St. Louis EPA Supersite for June 1, 2001 to May 31, 2003. We obtained ICD-9 information on 281,763 pediatric ED visits from 27 hospitals in the St. Louis, MO metropolitan area. The relationship between EC and pediatric asthma ED visits, controlling for season, weekend exposure, allergens, and other pollutants known to exacerbate asthma, was assessed using Poisson generalized estimating equations using a 1-day lag between exposure and ED visit. We evaluated the interaction of EC and temperature and EC and weekend vs. weekday exposure. An interaction effect existed between EC and temperature for 11-17-year-olds during the summer and winter seasons. During the summer, a 0.10 microg/m(3) increase in EC resulted in a 9.45% increase in asthma ED visits among 11-17-year-olds (95%CI = 1.02,1.17) at the median seasonal temperature (86.5 degrees F). This risk increased with increasing temperature. During the winter, a 0.10 microg/m(3) increase in EC resulted in 2.80% increase in asthma ED visits among 11-17-year-olds (95%CI = 1.01,1.05) at the median seasonal temperature (43.3 degrees F). This risk increased with decreasing temperature. Among 11-17-year-olds, daily number of asthma ED visits is associated with increased levels of EC at higher temperatures in the summer and lower temperatures in the winter.

Can fine particulate matter explain the paradoxical ozone associations?

Our previous paper entitled "Paradoxical ozone associations could be due to methyl nitrite from combustion of methyl ethers or esters in engine fuels" (Env. Int.. 2007;33;1090) reviewed 11 studies of the impact of ozone on human health that, paradoxically, found a negative coefficient for ozone-morbidity associations. We argued that the most likely explanation for this effect would be methyl nitrite (MN) as an unsuspected exhaust component of engines with methyl ether in the fuel. The basis of the argument was the fact that MN is rapidly destroyed by sunlight, so that MN would be negatively correlated with ozone. All (but one) of the reviewed studies concluded that criterion pollutants could not explain the negative slope. The argument was strengthened by the observation that such paradoxical ozone associations have not been found in regions without significant methyl ether in gasoline. Left unaddressed in the previous paper was the possibility that fine particulate matter (FPM) might explain the POA. If this were true, then it would be necessary that the FPM be negatively correlated with ozone in those regions that found a POA. The current paper reviews data on FPM-ozone correlations in those regions where a POA was identified. The results show that FPM was, in most cases, positively correlated with ozone and so could not explain the POA.

Effect of short-term exposure to air pollution and pollen on medical emergency calls: a case-crossover study in Spain

BACKGROUND

A symmetric case-crossover design was used to analyse the short-term relationship between air pollution, pollen and emergency calls to medical services.

METHODS

This study covered patients who made medical emergency calls in the City of Vigo (Spain) during the period 1996-1999. Morbidity data were obtained from the records of the 061 Medical Emergency Control Center, in its capacity as the body officially coordinating all medical emergencies by telephone. Air pollution data were furnished by the Vigo Municipal Air Pollution Surveillance Grid. Pollen levels were provided by the staff of the Spanish Aerobiology Network in Vigo.

RESULTS

A rise of 10 microg/m(3) in ambient particulate levels led to the risk of medical emergency calls requesting attention increasing by: (i) 1.97% [95% confidence interval (95% CI): 1.83-2.11%] for circulatory causes on the same day; (ii) 1.95% (95% CI: 1.76-2.14%) for respiratory causes at 2 days and (iii) 1.34% (95% CI: 1.23-1.45%) for combined circulatory and respiratory causes on the same day. A number of pollens displayed a statistically significant relationship with emergency calls. No interaction was in evidence between pollens and air pollutants.

CONCLUSIONS

While elevations in particulate air pollution increase medical emergency calls because of cardiac or respiratory causes or both combined, elevations in pollen levels increase medical emergency calls because of respiratory causes.

Tree pollen and hospitalization for asthma in urban Canada

BACKGROUND

Allergy to tree pollen is common and aeroallergens have been associated with severe asthma exacerbations in the community setting. To determine the impact of different trees on asthma, we tested the association between daily hospitalizations for asthma and daily concentrations of different tree pollens in 10 large Canadian cities.

METHODS

Daily time-series analyses were employed to remove unwanted temporal trends. For each family or genus, results were adjusted for day of the week, temperature, barometric pressure and relative humidity. Results were expressed as the percentage increase in asthma hospitalizations related to an increase in tree pollen concentration equivalent in magnitude to its interquartile range.

RESULTS

For an interquartile increase in daily tree pollen concentration, percent increases in daily hospitalization for asthma were: 2.63% (95% CI 1.19-4.07) for Ulmus (elm), 2.45% (1.12-3.78) for the group containing Pinaceae (pine, fir, spruce), Tsuga (hemlock) and Larix (larch, tamarack); 2.32% (0.93-3.71) for the group containing Quercus (oak) and Castanea (chestnut), and 2.16% (0.70-3.62) for Acer (boxelder and maple). Statistically significant (p < 0.05) but small (<2%) effects were observed for Fraxinus (ash), Populus (aspen, poplar), Alnus (alder), Betula (birch) and Corylus (hazelnut).

CONCLUSIONS

Several common tree pollens are an important cause of acute exacerbations of asthma severe enough to require hospitalization.

Associations between grass and weed pollen and emergency department visits for asthma among children in Montreal

CONTEXT AND OBJECTIVE

Asthma among children is a major public health problem worldwide. There are increasing number of studies suggesting a possible association between allergenic pollen and exacerbations of asthma. In the context of global climate change, a number of future climate and air pollution scenarios predict increases in concentrations of pollen, an extension of the pollen season, and an increase in the allergenicity of pollen. The goal of the present study is to evaluate the short-term effects of exposure to grass and weed pollen on emergency department visits and readmissions for asthma among children aged 0-9 years living in Montreal between April and October, 1994-2004.

METHODOLOGY AND RESULTS

Time-series analyses were carried out using parametric log-linear overdispersed Poisson models that were adjusted for temporal variations, daily weather conditions (temperature, atmospheric pressure), and gaseous air pollutants (ozone and nitrogen dioxide). We have found positive associations between emergency department visits and concentrations of grass pollen 3 days after exposure. The effect of grass pollen was higher on emergency department readmissions as compared to initial visits. Weak negative associations were found between weed pollen (including ragweed pollen) and emergency department visits 2 days after exposure.

CONCLUSION

The data indicate that among children, emergency department visits increased with increasing concentrations of grass pollen.

Air quality and pediatric asthma-related emergencies

BACKGROUND

Previous studies suggest a relationship between air pollutants, aeroallergens, and asthma exacerbations.

OBJECTIVE

To simultaneously examine the role of seasonality, air quality, aeroallergens, and climate on asthma-related pediatric emergency department (ED) visits.

METHODS

A retrospective 4-year study of asthma-related ED visits was conducted.

RESULTS

September had the highest number of visits (p < 0.01). There were lower temperatures and precipitation (p < 0.01) and higher tree and weed pollen levels (p = 0.05) on days with more visits (p = 0.05), while grass pollen, mold, ozone, NO2, and PM2.5 levels showed no significant differences.

CONCLUSIONS

Asthma-related visits were associated with aeroallergens and climatic factors and not air-quality factors.

Paradoxical ozone associations could be due to methyl nitrite from combustion of methyl ethers or esters in engine fuels

We review studies of the effects of low ambient ozone concentrations on morbidity that found a negative coefficient for ozone concentration. We call this a Paradoxical Ozone Association (POA). All studies were in regions with methyl ether in gasoline. All but one study carefully controlled for the effects of other criterion pollutants, so the phenomenon cannot be attributed to them. One was in southern California in mid-summer when ozone levels are highest. Because ozone is created by sunlight, the most plausible explanation for a POA would be an ambient pollutant that is rapidly destroyed by sunlight, such as methyl nitrite (MN). A previously published model of engine exhaust chemistry suggested methyl ether in the fuel will create MN in the exhaust. MN is known to be highly toxic, and closely related alkyl nitrites are known to induce respiratory sensitivity in humans. Support for the interpretation comes from many studies, including three linking asthma symptoms to methyl tertiary butyl ether (MTBE) and the observation that a POA has not been seen in regions without ether in gasoline. We also note that studies in southern California show a historical trend from more significant to less significant ozone-health associations. The timing of those changes is consistent with the known timing of the introduction of gasoline oxygenated with MTBE in that region.

Decompensation of pollen-induced asthma in two towns with different pollution levels in La Mancha, Spain

BACKGROUND

Allergic diseases have increased in industrialized countries and this increase is associated not only with genetic factors but also with lifestyle and environmental factors such as air pollution. Our hypothesis was that asthma in pollen-allergic patients from two towns with very different pollution levels in La Mancha (Spain) could be affected to a very different degree.

OBJECTIVE

Our objectives were to assess the risk factors associated with decompensation of pollen-induced asthma in the two towns and to perform a comparison between the patients from Puertollano (high pollution level) and Ciudad Real (low pollution level) with respect to daily symptoms, medication used and peak-flow measurements.

METHODS

We designed a cohort study with 137 patients (66 from Puertollano and 71 from Ciudad Real), conducted over 3 years (1999-2001) and including two pollen seasons. The two populations presented similar demographic and clinical characteristics. The variables studied included: area of residence, sex, age, smoking status, asthma symptoms and positive prick tests. Clinical decompensation was monitored by symptoms recorded on diary cards, twice daily peak-flow measurements and the use of protocolized medication.

RESULTS

There was a clinically relevant relationship between the place of residence and clinical decompensation. The risk of clinical decompensation in patients from Puertollano was up to three times higher than that of patients in Ciudad Real (P=0.034). Furthermore, patients from Puertollano and patients with moderate asthma presented more rapid decompensation compared with patients from Ciudad Real (P=0.020) and patients with mild asthma (P=0.049).

CONCLUSION

In conclusion, pollen-allergic asthmatics in Puertollano present a poorer clinical course and become decompensated earlier than those from Ciudad Real and it could be due to air pollution.

Analysis of short-term influences of ambient aeroallergens on pediatric asthma hospital visits

The objective of our study was to investigate the association between daily pediatric asthma hospital visits and daily concentrations of aeroallergens and their specific species. Records of daily asthma visits in Cincinnati area were retrieved from Cincinnati Children's Hospital Medical Center and aeroallergen sampling was performed by the Button Inhalable Sampler. The Poisson generalized linear model was carried out in which the log of the number of asthma hospital visits was related to aeroallergen level, treated as a continuous variable with adjustment for seasonal time trend, day of the week, ozone and PM(2.5) concentrations, temperature and humidity. The aeroallergens having a significant impact on asthma hospital visits were ragweed, oak/maple and Pinaceae pollen. Their relative risks on asthma hospital visits with respect to a 100 counts/m(3) increase in concentration were in the range of 1.23 to 1.54. The effects in causing the asthma exacerbation were delayed by 3 or 5 days.

Adverse health effects of outdoor air pollutants

Much research on the health effects of outdoor air pollution has been published in the last decade. The goal of this review is to concisely summarize a wide range of the recent research on health effects of many types of outdoor air pollution. A review of the health effects of major outdoor air pollutants including particulates, carbon monoxide, sulfur and nitrogen oxides, acid gases, metals, volatile organics, solvents, pesticides, radiation and bioaerosols is presented. Numerous studies have linked atmospheric pollutants to many types of health problems of many body systems including the respiratory, cardiovascular, immunological, hematological, neurological and reproductive/ developmental systems. Some studies have found increases in respiratory and cardiovascular problems at outdoor pollutant levels well below standards set by such agencies as the US EPA and WHO. Air pollution is associated with large increases in medical expenses, morbidity and is estimated to cause about 800,000 annual premature deaths worldwide [Cohen, A.J., Ross Alexander, H., Ostro, B., Pandey, K.D., Kryzanowski, M., Kunzail, N., et al., 2005. The global burden of disease due to outdoor air pollution. J Toxicol Environ Health A. 68: 1-7.]. Further research on the health effects of air pollution and air pollutant abatement methods should be very helpful to physicians, public health officials, industrialists, politicians and the general public.

Airborne fungal spores in a cross-sectional study of office buildings

Airborne fungal spores were measured in 44 office buildings in the summer and winter throughout the continental United States, as part of the Building Assessment, Survey and Evaluation (BASE) program. Six indoor air and two outdoor air samples were collected on a single day from each building. The cross-sectional and repeated measure design afforded evaluation of between-building and within-building variability of fungal spore levels in buildings. Total fungal spore concentrations in indoor air ranged from < 24 to 1000 spores/m3, except for one building with natural ventilation where indoor levels were approximately 9000 spores/m3. Indoor air concentrations of total spores did not vary significantly between winter and summer or morning and afternoon monitoring periods or among climate zones or locations within a test area. Indoor-outdoor ratios of total spore concentrations typically ranged between 0.01 and 0.1 and were approximately seven times greater in winter than summer because of relatively low outdoor levels in the winter. The indoor-outdoor ratio of total spore concentrations for a building was consistent (reliability coefficient = 0.91) among repeated measures. Distributions of rank correlation coefficients for spore types in pairs of individual indoor-outdoor and indoor-indoor samples were weakly correlated (Spearman correlation = 0.2 on average). When spore type data were aggregated among samples from the same building, the central tendency of the rank correlation coefficients increased to 0.45. Rank correlation coefficients were also proportional to the number of spore types present in the samples that were compared. The BASE study provides normative data on concentrations of fungal spores that can aid in identification of problematic levels of mold in buildings.

Temporal associations between daily counts of fungal spores and asthma exacerbations

BACKGROUND

Outdoor aeroallergens are one of a number of environmental factors thought to precipitate asthma exacerbations.

AIMS

To investigate the short term associations between daily fungal spore concentrations and indicators of daily asthma exacerbations in a large urban population.

METHODS

Daily counts of visits for asthma to family physicians and hospital accident and emergency (A&E) departments and emergency hospital admissions in London 1992-93 were compiled. Daily concentrations of fungal spores (30 species), daily average temperature, humidity, and concentrations of pollen and outdoor air pollution were also compiled. The analysis was restricted to the period when fungal spores were most prevalent (June to mid October). Non-parametric regression time series methods were used to assess associations controlling for seasonality, day of week, and meteorological factors. The sensitivity of the findings to the inclusion of pollen and air pollution into the models was also assessed.

RESULTS

In children aged 0-14 years the relative risks for increases in the number of A&E visits and hospital admissions associated with changes in fungal spore concentrations from the lower to upper quartiles were 1.06 (95% CI 0.94 to 1.18) and 1.07 (0.97 to 1.19) respectively. The addition of pollen or air pollutants had little impact on the observed associations. A number of individual spore taxa, in particular Alternaria, Epicoccum, Agrocybe, Mildews, and both coloured and colourless Basidiospores and Ascospores, were associated with increases in the number of emergency visits and hospital admissions for asthma, although the precision of these estimates were low. No evidence was found for associations in adults.

CONCLUSIONS

Fungal spore concentrations may provoke or exacerbate asthma attacks in children resulting in visits to A&E departments and emergency hospital admissions. These findings were unlikely to be due to confounding by other environmental factors. The associations were comparable to those observed for ambient air pollution from similarly designed studies.

Correlation of ambient inhalable bioaerosols with particulate matter and ozone: a two-year study

In this study, we have examined the relationships between the concentrations of ambient inhalable airborne fungi and pollen with PM10, PM2.5, ozone, organic carbon, selected trace metals (cadmium, copper, lead, and zinc), temperature, and relative humidity. The database was collected in Cincinnati, Ohio, USA, during two consecutive years. Measurements of all environmental variables were performed at the same site continuously 5 days a week except during winter months. The airborne concentrations of biological and non-biological pollutants ranged as follows: total fungi: 184-16 979 spores m(-3); total pollen: 0-6692 pollen m(-3); PM10: 6.70-65.38 microg m(-3); PM2.5: 5.04-45.02 microg m(-3); and ozone: 2.54-64.17 ppb. Higher levels of total inhalable fungi and particulate matter were found during fall and summer months. In contrast, total pollen concentration showed elevated levels in spring. Peak concentrations of ozone were observed during summer and beginning of fall. Our study concluded that several types of inhalable airborne fungi and pollen, particulate matter, and ozone could be positively correlated as a result of the atmospheric temperature influence.