The association between asthma-related emergency department visits and pollen and mold spore concentrations in the Bronx, 2001-2008

Airborne grass pollen and thunderstorms influence emergency department asthma presentations in a subtropical climate

BACKGROUND

Grass pollen is considered a major outdoor aeroallergen source worldwide. It is proposed as a mechanism for thunderstorm asthma that lightning during thunderstorms promotes electrical rupture of pollen grains that leads to allergic airway inflammation. However, most evidence of associations between grass pollen and asthma comes from temperate regions. The objective of this study was to investigate short-term associations between airborne grass pollen exposure and asthma emergency department presentations in a subtropical population.

METHODS

Episode level public hospital presentations for asthma (2016-2020) were extracted for greater Brisbane, Australia, from Queensland Health's Emergency Data Collection. Concentrations of airborne pollen were determined prospectively using a continuous flow volumetric impaction sampler. Daily time series analysis using a generalised additive mixed model were applied to determine associations between airborne grass pollen concentrations, and lightning count data, with asthma presentations.

RESULTS

Airborne grass pollen showed an association with asthma presentations in Brisbane; a significant association was detected from same day exposure to three days lag. Grass pollen exposure increased daily asthma presentations up to 48.5% (95% CI: 12%, 85.9%) in female children. Lightning did not modify the effect of grass pollen on asthma presentations, however a positive association was detected between cloud-to-cloud lightning strikes and asthma presentations (P = 0.048).

CONCLUSION

Airborne grass pollen exposure may exacerbate symptoms of asthma requiring urgent medical care of children and adults in a subtropical climate. This knowledge indicates an opportunity for targeted management of respiratory allergic disease to reduce patient and health system burden. For the first time, an influence of lightning on asthma was detected in this context. The outcomes support a need for continued pollen monitoring and surveillance of thunderstorm asthma risk in subtropical regions.

Trends in seasonal pollen and asthma-related morbidity among adults and children in a U.S. high-density urban center, 2001-2020

OBJECTIVE

To analyze the long-term trends in pollen counts and asthma-related emergency department visits (AREDV) in adult and pediatric populations in the Bronx.

METHODS

Daily values of adult and pediatric AREDV were retrospectively obtained from three major Bronx hospitals using ICD-10 codes and pollen counts were obtained from the Armonk station from 2001-2020. Wilcoxon Ranked Sum was applied to compare median values, while Spearman correlation was employed to examine the association between these variables, for both decades and each season.

RESULTS

The median value of pediatric AREDV increased by 200% from the 1st to 2nd decade (p < 0.001) and AREDV peak shifted from predominantly the spring season in the 1st decade to the fall and winter seasons in the 2nd decade. Seasonal patterns were consistent over 20 years with summer AREDV lower than all other seasons (9 vs. 17 per day) (p < 0.001). Spring tree pollen peaks were correlated with AREDV peaks (rho = 0.34) (p < 0.001). Tree pollen exceeding 100 grains/m³ corresponded to a median of 19.0 AREDVs while all other tree pollen (0 - 99 grains/m³) corresponded to a median of 15.0 AREDVs (p < 0.001). AREDVs sharply declined in 2020, coinciding with the emergence of COVID-19.

CONCLUSIONS

Pollen and AREDVs peak earlier in the spring and are more strongly interconnected, while asthma rates among children are rapidly rising, particularly in the fall and winter. These findings can advise targeted awareness campaigns for better management of asthma related morbidity.

A Review of the Respiratory Health Burden Attributable to Short-Term Exposure to Pollen

Respiratory diseases such as asthma, allergic rhinitis (AR) and chronic obstructive pulmonary disease (COPD) affect millions worldwide and pose a significant global public health burden. Over the years, changes in land use and climate have increased pollen quantity, allergenicity and duration of the pollen season, thus increasing its impact on respiratory disease. Many studies have investigated the associations between short-term ambient pollen (i.e., within days or weeks of exposure) and respiratory outcomes. Here, we reviewed the current evidence on the association between short-term outdoor pollen exposure and thunderstorm asthma (TA), asthma and COPD hospital presentations, general practice (GP) consultations, self-reported respiratory symptoms, lung function changes and their potential effect modifiers. The literature suggests strong evidence of an association between ambient pollen concentrations and almost all respiratory outcomes mentioned above, especially in people with pre-existing respiratory diseases. However, the evidence on sub-clinical lung function changes, COPD, and effect modifiers other than asthma, hay fever and pollen sensitisation are still scarce and requires further exploration. Better understanding of the implications of pollen on respiratory health can aid healthcare professionals to implement appropriate management strategies.

Worsening of chronic house-dust-mite-induced respiratory allergies: An observational survey in three European countries

Background

Although respiratory allergies to house dust mites (HDMs) can often be controlled with symptomatic medications, some patients do not achieve satisfactory disease control.

Objective

To assess fortnightly fluctuations (notably worsening and/or exacerbations) in disease parameters among patients taking only symptomatic medications for HDM allergy.

Methods

In a 13-month, observational, multicenter survey of adults with a self-reported history of poorly controlled, moderate-to-severe, physician-diagnosed HDM respiratory allergy in France, Italy, and Spain, fortnightly telephone interviews were used to gather information on medication use, symptoms, the disease burden, and medical consultations from late May 2012 to early July 2013.

Results

A total of 313 patients completed the study (n = 114 in Italy, 92 in France, and 107 in Spain). Although most participants reported improvements in symptoms, a substantial minority (ranging from 12% to 44% per fortnightly telephone interview in 2012 and from 16% to 37% in 2013) complained of worsening. A few study participants did not improve at any time in the study: 4% overall, and 2%, 2%, and 7% in Italy, France and Spain, respectively. A change in the weather and/or contact with other allergens were the most frequent self-reported reasons for worsening, although the answer “I don't know” was also prominent.

Conclusion

In a 13-month survey of patients with HDM allergy in Italy, France, and Spain, the participants’ symptom status fluctuated significantly — illustrating the complexity of this condition. Although most participants reported improvements, the “never-improver” profile warrants further investigation. More prominence could be given to symptom control and a low exacerbation risk as treatment goals in allergic rhinitis.

Pollen Exposure and Associated Healthcare Utilization: A Population-based Study Using HMO Data in the Washington, DC Area

Rationale: Most studies of the healthcare utilization impact of pollen exposure have focused on emergency department visits or hospital admissions. However, other frequent but lower cost services—phone calls and e-mails to providers and office visits—may also be affected.

Objectives: The objective of our study was to estimate the impact of tree and grass pollen exposures on respiratory-related healthcare utilization across a range of medical services, including calls and e-mails to providers, nonurgent face-to-face visits, urgent and emergent care visits, and hospitalizations.

Methods: We conducted a retrospective observational study of daily tree and grass pollen counts linked to electronic health records of Kaiser Permanente beneficiaries in the metropolitan Washington, DC, area for 2013–2014.

Results: The proportion of Kaiser Permanente beneficiaries with respiratory-related healthcare utilization was significantly greater (for P ⩽ 0.05) given a 1 standard deviation increase in same-day pollen exposure. For tree pollen, a 1 standard deviation increase in same-day pollen exposure was associated with relative increases in utilization ranging from 1.77% (95% confidence interval [CI], 0.07–4.17%) for urgent and emergent care visits to 12.84% (95% CI, 11.02–14.65%) for provider calls/e-mails. For grass pollen exposure, a 1 standard deviation increase in same-day pollen exposure was associated with relative increases in utilization ranging from 1.42% (95% CI, 0.39–2.46) for provider face-to-face visits to 11.09% (95% CI, 9.26–12.92) for provider calls/e-mails.

Conclusions: Increased pollen exposure was associated with increases in healthcare utilization across a range of services, with relatively higher increases in provider calls/e-mails and lower increases in emergent or acute care. If climate change increases intensity and geographic scope of pollen exposure as predicted and if this study’s estimates of association of peak pollen exposure on healthcare utilization are generalizable, then the impact of climate change on healthcare utilization may be significant.

Retrospective analysis of epidemic thunderstorm asthma in children in Yulin, northwest China

BACKGROUND

An epidemic of thunderstorm asthma in pediatric patients occurred in Yulin, a northwest city of China, on 11 September 2018. We described the epidemic and retrospectively analyzed the demographic and clinical aspects of the involved children.

METHODS

The caseload data of patients were collected from the hospital information system in Yulin Pediatric Hospital. The detailed document of hospitalized children with thunderstorm asthma was sourced from the medical records.

RESULTS

The mean number of daily visits to emergency/outpatient department and the daily admission to hospital were 2.7 and 16 times, respectively, than on the other days of September. A gender prominence of males was observed in both emergency/outpatient and inpatient department. Among the 51 hospitalized children with detailed medical records, 56% of them had never experienced or were diagnosed with asthma and 25% had confirmed diagnosis of asthma. Sixty-seven percent had a history of allergic rhinitis during August and September. Seventy-six percent of the hospitalized children presented as moderate asthma. Ninety-four percent of the pediatric patients had positive IgE against mugwort pollen and 78% were monosensitized to pollen.

CONCLUSION

Thunderstorm asthma can affect children, especially who has allergic rhinitis or asthma without preventive management. Mugwort is also an aeroallergen in thunderstorm asthma attacks.

IMPACT

Thunderstorm can induce asthma attacks in children with allergic rhinitis owing to mugwort and aggravate symptoms in children with confirmed diagnosis of asthma. Children with mugwort allergy are susceptible to thunderstorm asthma and a preponderance of boys was observed. Better identification of allergic children to mugwort, giving suitable protective measures during thunderstorm and standard therapy to existing allergic situation could be a benefit for children at risk of thunderstorm asthma.

Ambient daily pollen levels in association with asthma exacerbation among children in Philadelphia, Pennsylvania

Pollen from trees, grasses, and weeds can trigger asthma exacerbation in sensitized individuals. However, there are gaps in knowledge about the effects, such as the relative risks from different plant taxa and threshold levels of effect. We aimed to describe the local association between pollen and asthma exacerbation among children in the City of Philadelphia, and to evaluate whether effects are modified by children's characteristics and clinical factors (e.g., child's age, race/ethnicity, comorbidities). We conducted a time-stratified case-crossover study of pediatric (age <18 years) asthma exacerbation, with cases identified through electronic health records (EHR) of the Children's Hospital of Philadelphia (CHOP) health system from March through October in the years 2011-2016. Daily pollen counts were obtained from the local National Allergy Bureau certified pollen counter. We applied conditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for the association between the pollen level (vs. none detected) and odds of asthma exacerbation, adjusting for temperature, relative humidity, and holidays. We estimated same-day exposure effects, as well as effects from exposure lagged by up to 5 days. There were 35,040 asthma exacerbation events during the study period, with the majority occurring among black, non-Hispanic children (81.8%) and boys (60.4%). We found increased odds of asthma exacerbation among Philadelphia children in association with tree pollen, both for total tree pollen and most individual tree types. Increased odds from total tree pollen were observed at the lowest levels studied (≤5 grains/m³, unlagged, OR = 1.06, 95% CI: 1.02, 1.10), and exhibited a positive exposure-response pattern of effect; tree pollen levels above 1000 grains/m³ (unlagged) were associated with 64% increased odds of asthma exacerbation (95% CI: 1.45, 1.84). Grass pollen was associated with asthma exacerbation only at levels above the 99^th percentile (52 grains/m³), which occurred, on average, two days per year during the study period (with 2-day lag, OR = 1.38, 95% CI: 1.19, 1.60). There was an inverse association (reduced asthma exacerbation) with ragweed pollen that was consistent across analyses. Pollen from other weeds was associated with increased odds of asthma exacerbation, without a clear exposure-response pattern (2-day lag, significant increases ranging from 8% to 19%). Increased odds from tree pollen and weeds (other than ragweed) were higher among children with allergic rhinitis. While there are known benefits from urban vegetation for human health, there are risks as well. It is important to note, however, that pollen is released during a limited time frame each year, and advisories informed by local data can enable susceptible individuals to avoid outdoor exposure on high-risk days.

Urban Trees and Human Health: A Scoping Review

The urban forest is a green infrastructure system that delivers multiple environmental, economic, social and health services, and functions in cities. Environmental benefits of urban trees are well understood, but no review to date has examined how urban trees affect human health. This review provides a comprehensive summary of existing literature on the health impacts of urban trees that can inform future research, policy, and nature-based public health interventions. A systematic search used keywords representing human health, environmental health, and urban forestry. Following screening and appraisal of several thousand articles, 201 studies were conceptually sorted into a three-part framework. Reducing Harm, representing 41% of studies, includes topics such as air pollution, ultraviolet radiation, heat exposure, and pollen. Restoring Capacities, at 31%, includes attention restoration, mental health, stress reduction, and clinical outcomes. Building Capacities, at 28%, includes topics such as birth outcomes, active living, and weight status. The studies that were reviewed show substantial heterogeneity in purpose and method yet indicate important health outcomes associated with people’s exposure to trees. This review will help inform future research and practice, and demonstrates why urban forest planning and management should strategically promote trees as a social determinant of public health.

Automated Tool for Health Utility Assessments: The Gambler II

Background. The Gambler II is a web-based utility assessment tool supporting visual analogue scale (VAS), standard gamble (SG), and time trade-off (TTO) utility assessments. It contains novel features, including an easy to use project development authoring tool and use of multimedia clips for health state descriptions. Objectives. Evaluate the usability and understandability of the patient-facing side of The Gambler. Investigate the feasibility of using The Gambler and evaluate its impact on patient knowledge regarding the relevant health states. Materials and Methods. We used The Gambler to assess utilities on a convenience sample of 55 users for common long-term complications of type 2 diabetes mellitus: diabetic neuropathy, diabetic retinopathy, and diabetic foot infection requiring transmetatarsal amputation. Using VAS, SG, and TTO, we collected metadata, such as time spent on each assessment and the entire assessment process. We evaluated usability with an adaptation of the System Usability Scale survey and understandability. We evaluated impact on knowledge gained through knowledge assessments about these complications before and after use of The Gambler. Results. Overall satisfaction with The Gambler was high, 4.02 on a 5-point scale. Usability rated highly at 84.93 on a normalized scale between 0 and 100. Knowledge scores increased significantly following use of The Gambler from pretest mean of 68% to posttest mean of 76% (P < 0.01). Average time using the software: ∼7½ minutes. Conclusions. The Gambler is an easy to use and understand computer-based tool for utility assessment. It is feasible to use within clinical encounters to support shared decision making, and it has unique features that make it a powerful tool for investigators interested in research on health utilities.

Longitudinal trends in asthma emergency department visits, pollutant and pollen levels, and weather variables in the Bronx from 2001-2008

Objective: To evaluate how asthma-related emergency department visits (AREDV), air pollutant levels, pollen counts, and weather variables changed from 2001 to 2008 in the Bronx, NY. Methods: 42,065 daily AREDV values (1 January 2001 to 31 December 2008) were collected using our institution's Clinical Looking Glass software. Daily values of sulfur dioxide (SO₂), carbon monoxide (CO), ozone (O₃), nitrogen dioxide (NO₂), temperature, and humidity were obtained from the National Climatic Data Center's Bronx station. Daily tree pollen counts were obtained from the Armonk counting station near the Bronx. Median values for each variable were analyzed using the Mann-Whitney test to compare 2001-2004 and 2005-2008 values. Simple linear regression examined associations between AREDV and individual pollutants. Due to seasonal variations of the variables, each season was considered separately. Results: There were significant decreases for AREDV, SO₂, CO, and humidity for all seasons, and for NO₂ in the spring and winter. Significant increases occurred for O₃ in the spring, fall, and winter; for temperature in the summer and winter; and for tree pollen in the spring. Significant positive associations were found between AREDV and SO₂, CO, NO₂, and humidity, respectively, while significant negative associations were found between AREDV and O₃ and temperature, respectively. Conclusions: From 2001 to 2008, significant: a) decreases in AREDV, SO₂, CO, and humidity for all seasons, and decreases in NO₂ for the spring and winter; and b) increases in O₃, temperature, and spring tree pollen were observed. By tracking and anticipating environmental and pollutant changes, efforts can be made to minimize AREDV.

Effect of intra-urban temperature variation on tree flowering phenology, airborne pollen, and measurement error in epidemiological studies of allergenic pollen

Temperature gradients in cities can cause inter-neighborhood differences in the timing of pollen release. However, most epidemiological studies examining allergenic pollen utilize daily measurements from a single pollen monitoring station with the implicit assumption that the measured time series of airborne pollen concentrations applies across the study areas, and that the temporal mismatch between concentrations at the counting station and elsewhere in the study area is negligible. This assumption is tested by quantifying temperature using satellite imagery, observing flowering times of oak (Quercus) and mulberry (Morus) trees at multiple sites, and collecting airborne pollen. Epidemiological studies of allergenic pollen are reviewed and temperatures within their study areas are quantified. In this one-year study, peak oak flowering time was well explained by average February nighttime temperature (R2 = 0.94), which varied by 6 °C across Detroit. This relationship was used to predict flowering phenology across the study region. Peak flowering ranged from April 20-May 13 and predicted a substantial portion of relative airborne oak pollen concentrations in Detroit (R2 = 0.46) and at the regional pollen monitoring station (R2 = 0.61). The regional pollen monitoring station was located in a cooler outlying area where peak flowering occurred around May 12 and peak pollen concentrations were measured on May 15. This provides evidence that the timing of pollen release varies substantially within a metropolitan area and challenges the assumption that pollen measurements at a single location are representative of an entire city. Across the epidemiological studies, 50% of study areas were not within 1 °C (equal to a lag or lead of 4 days in flowering time) of temperatures at the pollen measurement location. Epidemiological studies using a single pollen station as a proxy for pollen concentrations are prone to significant measurement error if the study area is climatically variable.

The association between pollutant levels and asthma-related emergency department visits in the Bronx after the World Trade Center attacks

Objective: To examine the potential impact of the World Trade Center (WTC) attacks on asthma-related emergency department visits (AREDV) in the New York City borough of the Bronx. Methods: We obtained daily nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and ozone (O₃) values from the National Climatic Data Center's collection station in the Bronx from 1999 and 2002, a year before and after the WTC attacks. We compared daily AREDV and pollutant levels between 1999 and 2002 using the Wilcoxon signed rank sum test. We considered each season separately due to seasonal variations of AREDV and pollutants. We then used multiple linear regression models to assess the relationships between the changes in AREDV and the changes in pollutants from 1999 to 2002 in each season. Results: There were statistically significant increases from 1999 to 2002 in the daily NO₂ in the summer. Significant increases for daily SO₂ and O₃ values from 1999 to 2002 occurred in all seasons. Significant increases occurred in daily AREDV values in the spring and fall. Multiple linear regression analyses showed that increases in the daily O₃ values were significantly associated with increases in AREDV from 1999 to 2002 in the summer season. Conclusion: We observed a possible association between the WTC attacks and significant increases in O₃ and SO₂ for all seasons, and NO₂ for the summer. AREDV significantly increased following the WTC attacks. Increases in daily O₃ values were significantly associated with increases in AREDV in the summer season.

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

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

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.

Levels and determinants of tree pollen in New York City

Exposure to allergenic tree pollen is a risk factor for multiple allergic disease outcomes. Little is known about how tree pollen levels vary within cities and whether such variation affects the development or exacerbation of allergic disease. Accordingly, we collected integrated pollen samples at uniform height at 45 sites across New York City during the 2013 pollen season. We used these monitoring results in combination with adjacent land use data to develop a land use regression model for tree pollen. We evaluated four types of land use variables for inclusion in the model: tree canopy, distributed building height (a measure of building volume density), elevation, and distance to water. When included alone in the model, percent tree canopy cover within a 0.5 km radial buffer explained 39% of the variance in tree pollen (1.9% increase in tree pollen per one-percentage point increase in tree canopy cover, P<0.0001). The inclusion of additional variables did not improve model fit. We conclude that intra-urban variation in tree canopy is an important driver of tree pollen exposure. Land use regression models can be used to incorporate spatial variation in tree pollen exposure in studies of allergic disease outcomes.

Sensitization to Fungi in Atopic Dermatitis Patients 14 Year and Older - Association with Other Atopic Diseases and Parameters

Background:

Fungi as a source of allergen are still largely neglected in basic research as well as in clinical practice. This study aimed to highlight the impact of fungal allergens in a group of patients suffering from atopic dermatitis (AD).

Aims and Objectives:

The evaluation of the sensitization to fungi in AD patients aged 14 year and older and the evaluation of the relation of fungal sensitization to the occurrence of other atopic diseases and parameters.

Materials and Methods:

All patients satisfying inclusion criteria attending our hospital between 2008 and 2017 were included in the study. The complete dermatological and allergological examinations were performed in all included patients including examination of specific immunoglobulin E, skin prick test to mixture of fungi and inhalant allergens, evaluation of asthma bronchiale, rhinitis, onset of AD, family history about atopy, duration of eczematous lesions, severity of AD. Pairs of these categories were entered in the contingency tables and the Chi-square test for relationship of these variables was performed with the level of significance set below 5%.

Results:

Three hundred and thirty-one patients were included in the study; the average age was 26.8 years. The sensitization to fungi was recorded in 100 patients (30%). In these patients, the occurrence of asthma bronchiale, rhinitis, family history about atopy, sensitization to grass and trees was significantly higher than in patients without sensitization to fungi. We did not find any significant relation between the sensitization to fungi and the severity of AD, no relation was also found between the sensitization to fungi and sensitization to mites, animal dander, bird feather, and dust.

Conclusion:

The occurrence of asthma bronchiale, rhinitis, family history about atopy, sensitization to grass and trees was significantly higher in AD patients with sensitization to fungi. No relation was found between the severity of AD and the sensitization to fungi.

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

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

Ambient ozone and asthma hospital admissions in Texas: a time-series analysis

Background

Many studies have evaluated associations between asthma emergency department (ED) visits, hospital admissions (HAs), and ambient ozone (O₃) across the US, but not in Texas. We investigated the relationship between O₃ and asthma HAs, and the potential impacts of outdoor pollen, respiratory infection HAs, and the start of the school year in Texas.

Methods

We obtained daily time-series data on asthma HAs and ambient O₃ concentrations for Dallas, Houston, and Austin, Texas for the years 2003–2011. Relative risks (RRs) and 95% confidence intervals (CIs) of asthma HAs per 10-ppb increase in 8-h maximum O₃ concentrations were estimated from Poisson generalized additive models and adjusted for temporal trends, meteorological factors, pollen, respiratory infection HAs, day of the week, and public holidays. We conducted a number of sensitivity analyses to assess model specification.

Results

We observed weak associations between total asthma HAs and O₃ at lags of 1 day (RR_{10 ppb} = 1.012, 95% CI: 1.004–1.021), 2 days (RR_{10 ppb} = 1.011, 95% CI: 1.002–1.019), and 0–3 days (RR_{10 ppb} = 1.017, 95% CI: 1.005–1.030). The associations were primarily observed in children aged 5–14 years (e.g., for O₃ at lag 0–3 days, RR_{10 ppb} = 1.037, 95% CI: 1.011–1.064), and null in individuals 15 years or older. The effect estimates did not change significantly with adjustment for pollen and respiratory infections, but they attenuated considerably and lost statistical significance when August and September data were excluded. A significant interaction between time around the start of the school year and O₃ at lag 2 day was observed, with the associations with pediatric asthma HAs stronger in August and September (RR_{10 ppb} = 1.040, 95% CI: 1.012–1.069) than in the rest of the year (October–July) (RR_{10 ppb} = 1.006, 95% CI: 0.986–1.026).

Conclusions

We observed small but statistically significant positive associations between total and pediatric asthma HAs and short-term O₃ exposure in Texas, especially in August and September. Further research is needed to determine how the start of school could modify the observed association between O₃ and pediatric asthma HAs.

Electronic supplementary material

The online version of this article (doi:10.1186/s40733-017-0034-1) contains supplementary material, which is available to authorized users.

Feasibility of Deploying Inhaler Sensors to Identify the Impacts of Environmental Triggers and Built Environment Factors on Asthma Short-Acting Bronchodilator Use

BACKGROUND

Epidemiological asthma research has relied upon self-reported symptoms or healthcare utilization data, and used the residential address as the primary location for exposure. These data sources can be temporally limited, spatially aggregated, subjective, and burdensome for the patient to collect.

OBJECTIVES

First, we aimed to test the feasibility of collecting rescue inhaler use data in space-time using electronic sensors. Second, we aimed to evaluate whether these data have the potential to identify environmental triggers and built environment factors associated with rescue inhaler use and to determine whether these findings would be consistent with the existing literature.

METHODS

We utilized zero-truncated negative binomial models to identify triggers associated with inhaler use, and implemented three sensitivity analyses to validate our findings.

RESULTS

Electronic sensors fitted on metered dose inhalers tracked 5,660 rescue inhaler use events in space and time for 140 participants from 13 June 2012 to 28 February 2014. We found that the inhaler sensors were feasible in passively collecting objective rescue inhaler use data. We identified several environmental triggers with a positive and significant association with inhaler use, including: AQI, PM10, weed pollen, and mold. Conversely, the spatial distribution of tree cover demonstrated a negative and significant association with inhaler use.

CONCLUSIONS

Utilizing a sensor to capture the signal of rescue inhaler use in space-time offered a passive and objective signal of asthma activity. This approach enabled detailed analyses to identify environmental triggers and built environment factors that are associated with asthma symptoms beyond the residential address. The application of these new technologies has the potential to improve our surveillance and understanding of asthma. Citation: Su JG, Barrett MA, Henderson K, Humblet O, Smith T, Sublett JW, Nesbitt L, Hogg C, Van Sickle D, Sublett JL. 2017. Feasibility of deploying inhaler sensors to identify the impacts of environmental triggers and built environment factors on asthma short-acting bronchodilator use. Environ Health Perspect 125:254-261; http://dx.doi.org/10.1289/EHP266.

Pollen concentration and asthma exacerbations in Wake County, North Carolina, 2006-2012

Pollen has been generally linked to an increased risk for asthma exacerbation. However, the delayed effect (lag), the length of effect duration, and the association heterogeneity by pollen types have not been well characterized. Short-term associations between ambient concentration of various pollen types (tree, grass, and weed) and emergency department (ED) visits for asthma were assessed using data in Wake County, North Carolina, during 2006-2012. Distributed lag nonlinear models (DLNM) were used to characterize the associations, while adjusting for air pollutants, meteorological, and temporal factors. A strong association between same-day tree pollen and asthma ED visits was detected. This association lasted four days, with a 4-day cumulative risk ratio (RR) up to 2.10 (3500 grains/m(3) vs. 0 grains/m(3), 95% confidence interval [CI]=1.21-3.65). The associations of asthma ED visits with weed pollen and grass pollen were weak, suggestively starting from lag 2 and lasting 3 days, with the strongest association a 3-day cumulative RR of 1.08 (32 grains/m(3) vs. 0 grains/m(3), 95% CI=1.01-1.15) and 1.05 (11 grains/m(3) vs. 0 grains/m(3), 95% CI=1.00-1.11). Our results indicate that the association of ambient pollen and asthma exacerbation vary by pollen type, both quantitatively and temporally. These findings have important implications for optimizing targeted allergic disease prevention and management, and helping understand the etiology of ambient exposure-induced allergic diseases.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Outdoor temperature changes and emergency department visits for asthma in Seoul, Korea: A time-series study

BACKGROUND

Extreme temperatures and temperature changes are known indicators of climate change, and large temperature variations for several consecutive days may affect human health such as exacerbating respiratory symptoms. The objective of this study was to determine the association between outdoor temperature change and asthma-related emergency department visits. In particular, this study examined seasonality and identified susceptible populations, such as the elderly.

METHODS

The health data for asthma-related emergency department visits were collected from July 1, 2007, to December 31, 2010 in Seoul, Korea, through the National Emergency Department Information System of the National Emergency Medical Center and we defined temperature change as the absolute difference of mean temperature between the current day and the previous day. We applied generalized linear models with an allowance of over-dispersion for quantifying the estimated effects of temperature change on asthma-related emergency department visits, adjusting for meteorological conditions, air pollution, and time trend.

RESULTS

In general, temperature change was adversely associated with asthma-related emergency department visits, with a 1-unit increase of temperature change associated with a 3.5% (95% CI 0.7, 6.4%) increase in emergency department visits. In addition, seasonal variation after adjusting for mean temperature and diurnal temperature range had an adverse effect in spring, summer, and fall and a protective effect in winter. Patients aged ≥65 years experienced the most prominent effect during the fall, with a 17.9% (95% CI 4.1, 33.6%) increase in emergency department visits per 1-unit increase of temperature change, whereas the other seasons showed no statistically significant association.

CONCLUSIONS

Along with diurnal temperature range, temperature change may be an alternative indicator of climate change. Temperature change variables are well-known and easy to communicate with the public relative to the health effects of outdoor temperature fluctuations.