Stormy weather: a retrospective analysis of demand for emergency medical services during epidemic thunderstorm asthma

Refining ambulance clinical response models: The impact on ambulance response and emergency department presentations

OBJECTIVE

The ambulance service in Victoria, Australia implemented a revised clinical response model (CRM) in 2016 which was designed to increase the diversion of low-acuity Triple Zero (000) calls to secondary telephone triage and reduce emergency ambulance dispatches. The present study evaluates the influence of the revised CRM on emergency ambulance response times and ED presentations.

METHODS

A retrospective study of emergency calls for ambulance between 1 January 2015 and 31 December 2018. Ambulance data were linked with ED presentations occurring up to 48 h after contact. Interrupted time series analyses were used to evaluate the impact of the revised CRM.

RESULTS

A total of 2 365 529 calls were included. The proportion allocated a Code 1 (time-critical, lights/sirens) dispatch decreased from 56.6 to 41.0% after implementation of the revised CRM. The proportion of calls not receiving an emergency ambulance increased from 10.4 to 19.6%. Interrupted time series analyses demonstrated an improvement in Code 1 cases attended within 15 min (Key Performance Indicator). However, for patients with out-of-hospital cardiac arrest or requiring lights and sirens transport to hospital, there was no improvement in response time performance. By the end of the study period, there was also no difference in the proportion of callers presenting to ED when compared with the estimated proportion assuming the revised CRM had not been implemented.

CONCLUSION

The revised CRM was associated with improved Code 1 response time performance. However, there was no improvement in response times for high acuity patients, and no change in the proportion of callers presenting to ED.

Climate change and epigenetic biomarkers in allergic and airway diseases

Human epigenetic variation is associated with both environmental exposures and allergic diseases and can potentially serve as a biomarker connecting climate change with allergy and airway diseases. In this narrative review, we summarize recent human epigenetic studies examining exposure to temperature, precipitation, extreme weather events, and malnutrition to discuss findings as they relate to allergic and airway diseases. Temperature has been the most widely studied exposure, with the studies implicating both short-term and long-term exposures with epigenetic alterations and epigenetic aging. Few studies have examined natural disasters or extreme weather events. The studies available have reported differential DNA methylation of multiple genes and pathways, some of which were previously associated with asthma or allergy. Few studies have integrated climate-related events, epigenetic biomarkers, and allergic disease together. Prospective longitudinal studies are needed along with the collection of target tissues beyond blood samples, such as nasal and skin cells. Finally, global collaboration to increase diverse representation of study participants, particularly those most affected by climate injustice, as well as strengthen replication, validation, and harmonization of measurements will be needed to elucidate the impacts of climate change on the human epigenome.

Assessing the Effect of Precipitation on Asthma Emergency Department Visits in New York State From 2005 to 2014: A Case-Crossover Study

The Earth's precipitation patterns are changing, and regional precipitation is expected to continue to increase in New York State (NYS). Heavy precipitation may negatively affect asthma prevalence through its effect on seasonally varying allergens. We employed a threshold analysis using a time-stratified semi-symmetric bi-directional case-crossover study design to assess the effect of increase in precipitation on asthma (ICD-9 code 493.xx, N = 970,903) emergency department (ED) visits between 2005 and 2014 during non-winter months in NYS. Spatially contiguous gridded meteorological data from North American Land Data Assimilation System (NLDAS) were utilized. We used conditional logistic regression models and stratified the analyses by seasons. During non-winter months, we found a small, statistically significant risk of asthma ED visits for precipitation levels above 50 mm, with differences by season. These results suggest that heavy precipitation may be related to an increased risk of asthma ED visits. Gridded meteorological estimates provide a means of addressing the gaps in exposure classification, and these findings provide opportunities for further research on interactions with aeroallergens and meteorological conditions in the context of climate and health.

Climate change, air pollution, pollen allergy and extreme atmospheric events

PURPOSE OF REVIEW

Respiratory allergy correlates strictly with air pollution and climate change. Due to climate change, the atmospheric content of trigger factors such as pollens and moulds increase and induce rhinitis and asthma in sensitized patients with IgE-mediated allergic reactions.Pollen allergy is frequently used to evaluate the relationship between air pollution and allergic respiratory diseases. Pollen allergens trigger the release of immunomodulatory and pro-inflammatory mediators and accelerate the onset of sensitization to respiratory allergens in predisposed children and adults. Lightning storms during pollen seasons can exacerbate respiratory allergy and asthma not only in adults but also in children with pollinosis. In this study, we have focalized the trigger (chemical and biologic) factors of outdoor air pollution.

RECENT FINDINGS

Environmental pollution and climate change have harmful effects on human health, particularly on respiratory system, with frequent impact on social systems.Climate change is characterized by physic meteorological events inducing increase of production and emission of anthropogenic carbon dioxide (CO 2 ) into the atmosphere. Allergenic plants produce more pollen as a response to high atmospheric levels of CO 2 . Climate change also affects extreme atmospheric events such as heat waves, droughts, thunderstorms, floods, cyclones and hurricanes. These climate events, in particular thunderstorms during pollen seasons, can increase the intensity of asthma attacks in pollinosis patients.

SUMMARY

Climate change has important effects on the start and pathogenetic aspects of hypersensitivity of pollen allergy. Climate change causes an increase in the production of pollen and a change in the aspects increasing their allergenic properties. Through the effects of climate change, plant growth can be altered so that the new pollen produced are modified affecting more the human health. The need for public education and adoption of governmental measures to prevent environmental pollution and climate change are urgent. Efforts to reduce greenhouse gases, chemical and biologic contributors to air pollution are of critical importance. Extreme weather phenomena such as thunderstorms can trigger exacerbations of asthma attacks and need to be prevented with a correct information and therapy.

Climate change and respiratory disease: clinical guidance for healthcare professionals

Climate change is one of the major public health emergencies with already unprecedented impacts on our planet, environment and health. Climate change has already resulted in substantial increases in temperatures globally and more frequent and extreme weather in terms of heatwaves, droughts, dust storms, wildfires, rainstorms and flooding, with prolonged and altered allergen and microbial exposure as well as the introduction of new allergens to certain areas. All these exposures may have a major burden on patients with respiratory conditions, which will pose increasing challenges for respiratory clinicians and other healthcare providers. In addition, complex interactions between these different factors, along with other major environmental risk factors (e.g. air pollution), will exacerbate adverse health effects on the lung. For example, an increase in heat and sunlight in urban areas will lead to increases in ozone exposure among urban populations; effects of very high exposure to smoke and pollution from wildfires will be exacerbated by the accompanying heat and drought; and extreme precipitation events and flooding will increase exposure to humidity and mould indoors. This review aims to bring respiratory healthcare providers up to date with the newest research on the impacts of climate change on respiratory health. Respiratory clinicians and other healthcare providers need to be continually educated about the challenges of this emerging and growing public health problem and be equipped to be the key players in solutions to mitigate the impacts of climate change on patients with respiratory conditions.

Educational aims

To define climate change and describe major related environmental factors that pose a threat to patients with respiratory conditions.To provide an overview of the epidemiological evidence on climate change and respiratory diseases.To explain how climate change interacts with air pollution and other related environmental hazards to pose additional challenges for patients.To outline recommendations to protect the health of patients with respiratory conditions from climate-related environmental hazards in clinical practice.To outline recommendations to clinicians and patients with respiratory conditions on how to contribute to mitigating climate change.

A new fluorescence-based methodology for studying bioaerosol scavenging processes using a hyperspectral LIF-LIDAR remote sensing system

This paper presents a novel experimental approach to in-situ study of atmospheric phenomena such as nucleation scavenging by biological seeds, bio-droplet dehydration, and bioaerosol's particle scavenging by raindrops. Our methodology is based on the analysis of the dynamical changes of fluorescence signal. We use a remote sensing system based on a homebuilt hyperspectral laser induced fluorescence (LIF) Lidar to measure the transient back-fluorescence and backscattering signals. The spectral line shape of the transient fluorescence associated with an aerosolized tryptophan solution was first analyzed in the laboratory. It then used to study bioaerosol phase transitions between wet and dry conditions. The experiments were first conducted in a dynamic aerosol cell where we repetitively create and monitor the droplets containing bioaerosol cloud starting from its early formation till its total evaporation. The LIF-Lidar was used to simultaneously measure back-fluorescence, scattering and transmission. These measurements were synchronized with the generation of droplets containing bioaerosol and with the monitoring of aerosol's size distribution and ambient conditions. A novel optical receiver design was used to simultaneously detect both back-fluorescence polarization components. Results showed that along with droplet's evaporation process, bioaerosol's fluorescence spectrum exhibit a blue shift, known as the dynamic Stokes-shifts, of ∼2000 cm^-1 and an increase in its fluorescence anisotropy. To the best of our knowledge, this is the first report of fluorescence Stokes-shifts and anisotropy within microdroplets containing a biological solution due to wet-dry phase transitions. This method was also used to quantify scavenging of biological particle by raindrops from 100 m. It shows that valuable information can be derived from analyzing the fluorescence spectrum of bioaerosol within a cloud and demonstrate the potential of a LIF-LIDAR remote system to perform in-situ studies of scavenging processes.

The perfect storm: temporal analysis of air during the world's most deadly epidemic thunderstorm asthma (ETSA) event in Melbourne

BACKGROUND

There have been 26 epidemic thunderstorm asthma (ETSA) events worldwide, with Melbourne at the epicentre of ETSA with 7 recorded events, and in 2016 experienced the deadliest ETSA event ever recorded. Health services and emergency departments were overwhelmed with thousands requiring medical care for acute asthma and 10 people died.

OBJECTIVES

This multidisciplinary study was conducted across various health and science departments with the aim of improving our collective understanding of the mechanism behind ETSA.

DESIGN

This study involved time-resolved analysis of atmospheric sampling of the air for pollen and fungal spores, and intact and ruptured pollen compared with different weather parameters, pollution levels and clinical asthma presentations.

METHODS

Time-resolved pollen and fungal spore data collected by Deakin AirWATCH Burwood, underwent 3-h analysis, to better reflect the 'before', 'during' and 'after' ETSA time points, on the days leading up to and following the Melbourne 2016 event. Linear correlations were conducted with atmospheric pollution data provided by the Environment Protection Authority (EPA) of Victoria, weather data sourced from Bureau of Meteorology (BOM) and clinical asthma presentation data from the Victorian Agency for Health Information (VAHI) of Department of Health.

RESULTS

Counts of ruptured grass pollen grains increased 250% when the thunderstorm outflow reached Burwood. Increased PM10, high relative humidity, decreased temperature and low ozone concentrations observed in the storm outflow were correlated with increased levels of ruptured grass pollen. In particular, high ozone levels observed 6 h prior to this ETSA event may be a critical early indicator of impending ETSA event, since high ozone levels have been linked to increasing pollen allergen content and reducing pollen integrity, which may in turn contribute to enhanced pollen rupture.

CONCLUSION

The findings presented in this article highlight the importance of including ruptured pollen and time-resolved analysis to forecast ETSA events and thus save lives.

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.

Prediction of airborne pollen concentrations by artificial neural network and their relationship with meteorological parameters and air pollutants

After the early rainfall in the autumn of 2013, respiratory syndromes spread in the Khuzestan province of Iran with the most severity in Ahvaz. There have been recurring outbreaks in recent years. Considering that pollen-derived airborne allergens are regarded as key aeroallergens and the main cause of allergic rhinitis and asthma, this work aimed to forecast total pollen concentration in Ahvaz through an artificial neural network (ANN), followed by evaluating the pollen spatial distribution across the city and the association between pollen concentrations and environmental parameters. The utilized ANN in this work included an input layer with 13 parameters, a hidden layer of five neurons, and an output layer. Data were classified into training, validation, and testing sets. The ANN was implemented with 70% and 80% of data for training. The value of the correlation coefficient for the data validation of these two networks was 0.89 and 0.92, respectively. The results also indicated that despite the difference in the mean concentration of the pollens in various areas of Ahvaz, this difference was not statistically significant (P > 0.05). Furthermore, there was a negative correlation between the concentration of total pollen and relative humidity, precipitation, and air pressure. However, it had a positive correlation with temperature. Consequently, considering the logistical challenges of monitoring bioaerosols in the air, the ANN approach could predict total pollen concentrations. Therefore, in addition to measurements, the ANN technique can be a good tool to enable authorities to mitigate the impact of airborne pollen on people.

The association between outdoor allergens - pollen, fungal spore season and high asthma admission days in children and adolescents

Periods when asthma admissions peaks have serious implications for asthma sufferers and hospitals. We assessed the association between aeroallergen exposure and childhood asthma peak periods during two grass pollen seasons using the Melbourne Air Pollen Children and Adolescent Health (MAPCAH) study conducted in Melbourne, Australia. Two peak periods were identified. Effect modifications by atopy and sex were considered. All pollen 2 days prior was associated with increased odds of these peak periods. Same day fungal spores, but not pollen, were important. Grass at lag 2 was associated with increased odds 1.03 (95%CI 1.01, 1.05) as was the same day Alternaria 1.02 (1.00, 1.04) per spore/m³ for boys. In addition to pollen, fungal spores particularly Alternaria may result in days of high exacerbations during pollen seasons. Further guidance is needed to better prepare families/carers with information about the increased risk of asthma attacks in children prior to pollen seasons.

Combined Exposure to Birch Pollen and Thunderstorms Affects Respiratory Health in Stockholm, Sweden-A Time Series Analysis

Background: Thunderstorm asthma is a term used to describe surges in acute respiratory illnesses following a thunderstorm and is often attributed to an intense exposure to aeroallergens. Several episodes of thunderstorm asthma have been observed worldwide; however, no such cases have been described in Sweden. In Sweden, the most prominent exposure to air-borne pollen occurs during the blooming of the birch. We aimed to explore the associations between respiratory health and the combined exposure to thunderstorms and birch pollen. Methods: We investigated the association between the daily numbers of outpatient visits due to respiratory cases and the combined exposure to thunderstorms and birch pollen during the period of 1 May–31 September in 2001–2017, in Stockholm County, Sweden, by using time series analysis with log linear models. Results: We detected noticeable increases in the number of outpatient visits on both the same day (max 26%; 95% CI 1.16–1.37) and the day after (max 50%; 95% CI 1.32–1.70) the occurrence of a thunderstorm, when the concentrations of birch pollen and the number of lightning discharges were within the highest categories. Conclusions: It is possible that co-exposure to heavy thunderstorms and high concentrations of birch pollen affects the respiratory health of the Stockholm population. To the best of our knowledge, this is the first study addressing the thunderstorm-related respiratory illnesses in Sweden and the effects of birch pollen. Our study may be important for future public health advice related to thunderstorm asthma.

Exposure Assessment for Tropical Cyclone Epidemiology

PURPOSE OF REVIEW

Tropical cyclones impact human health, sometimes catastrophically. Epidemiological research characterizes these health impacts and uncovers pathways between storm hazards and health, helping to mitigate the health impacts of future storms. These studies, however, require researchers to identify people and areas exposed to tropical cyclones, which is often challenging. Here we review approaches, tools, and data products that can be useful in this exposure assessment.

RECENT FINDINGS

Epidemiological studies have used various operational measures to characterize exposure to tropical cyclones, including measures of physical hazards (e.g., wind, rain, flooding), measures related to human impacts (e.g., damage, stressors from the storm), and proxy measures of distance from the storm's central track. The choice of metric depends on the research question asked by the study, but there are numerous resources available that can help in capturing any of these metrics of exposure. Each has strengths and weaknesses that may influence their utility for a specific study. Here we have highlighted key tools and data products that can be useful for exposure assessment for tropical cyclone epidemiology. These results can guide epidemiologists as they design studies to explore how tropical cyclones influence human health.

Ghost in the machine or monkey with a typewriter-generating titles for Christmas research articles in The BMJ using artificial intelligence: observational study

OBJECTIVE

To determine whether artificial intelligence (AI) can generate plausible and engaging titles for potential Christmas research articles in The BMJ.

DESIGN

Observational study.

SETTING

Europe, Australia, and Africa.

PARTICIPANTS

1 AI technology (Generative Pre-trained Transformer 3, GPT-3) and 25 humans.

MAIN OUTCOME MEASURES

Plausibility, attractiveness, enjoyability, and educational value of titles for potential Christmas research articles in The BMJ generated by GPT-3 compared with historical controls.

RESULTS

AI generated titles were rated at least as enjoyable (159/250 responses (64%) v 346/500 responses (69%); odds ratio 0.9, 95% confidence interval 0.7 to 1.2) and attractive (176/250 (70%) v 342/500 (68%); 1.1, 0.8 to 1.4) as real control titles, although the real titles were rated as more plausible (182/250 (73%) v 238/500 (48%); 3.1, 2.3 to 4.1). The AI generated titles overall were rated as having less scientific or educational merit than the real controls (146/250 (58%) v 193/500 (39%); 2.0, 1.5 to 2.6); this difference, however, became non-significant when humans curated the AI output (146/250 (58%) v 123/250 (49%); 1.3, 1.0 to 1.8). Of the AI generated titles, the most plausible was "The association between belief in conspiracy theories and the willingness to receive vaccinations," and the highest rated was "The effects of free gourmet coffee on emergency department waiting times: an observational study."

CONCLUSIONS

AI can generate plausible, entertaining, and scientifically interesting titles for potential Christmas research articles in The BMJ; as in other areas of medicine, performance was enhanced by human intervention.

Predicting Covid-19 emergency medical service incidents from daily hospitalisation trends

INTRODUCTION

The aim of our retrospective study was to quantify the impact of Covid-19 on the temporal distribution of emergency medical services (EMS) demand in Travis County, Austin, Texas and propose a robust model to forecast Covid-19 EMS incidents.

METHODS

We analysed the temporal distribution of EMS calls in the Austin-Travis County area between 1 January 2019 and 31 December 2020. Change point detection was performed to identify the critical dates marking changes in EMS call distributions, and time series regression was applied for forecasting Covid-19 EMS incidents.

RESULTS

Two critical dates marked the impact of Covid-19 on the distribution of EMS calls: March 17th, when the daily number of non-pandemic EMS incidents dropped significantly, and 13 May, by which the daily number of EMS calls climbed back to 75% of the number in pre-Covid-19 time. The new daily count of the hospitalisation of Covid-19 patients alone proves a powerful predictor of the number of pandemic EMS calls, with an r² value equal to 0.85. In particular, for every 2.5 cases, where EMS takes a Covid-19 patient to a hospital, one person is admitted.

CONCLUSION

The mean daily number of non-pandemic EMS demand was significantly less than the period before the Covid-19 pandemic. The number of EMS calls for Covid-19 symptoms can be predicted from the daily new hospitalisation of Covid-19 patients. These findings may be of interest to EMS departments as they plan for future pandemics, including the ability to predict pandemic-related calls in an effort to adjust a targeted response.

Intramuscular corticosteroid injections in seasonal allergic rhinitis: A systematic review

OBJECTIVE

Seasonal allergic rhinitis (SAR) is an exaggerated immunological reaction to allergens (pollen) in the air. In a small subgroup of patients, SAR can be difficult to control with first-line therapy. Intramuscular corticosteroid injections (IMCIs) are an additional treatment in this subgroup of SAR patients. The aim of this systematic review is to investigate the efficacy and safety of IMCIs in SAR.

METHODS

Titles and abstracts were independently screened, followed by full-text screening based on predefined criteria. Included articles were critically appraised using the Cochrane Risk of Bias 2 (RoB 2) tool. The primary outcome is reported as the final conclusion about efficacy that was stated in the included studies. The secondary outcome is the safety of IMCIs with regard to long lasting side-effects.

RESULTS

The search yielded 2139 records, of which 10 were relevant and valid for our clinical question. Critical appraisal showed high risk of bias, which was due to unclear description of methods. Four out of four placebo-controlled, randomized controlled trials reported a significant and relevant difference in efficacy in favor of IMCIs compared with placebo. The occurrence of side-effects was not different between IMCIs and placebo or oral corticosteroids (OCs).

CONCLUSION

The outcome of this systematic review on trials concerning intramuscular steroid injections, despite being based on individual studies claiming favorable outcome with their use, is "inconclusive." This is because of the epidemiological high risk of bias in these studies that were mostly executed more than 30 years ago. The "inconclusive" rating allows for a description as an "optional therapy" for severe cases in guideline formation.

Use of a metalearner to predict emergency medical services demand in an urban setting

OBJECTIVE

To develop and internally validate a metalearner algorithm to predict the hourly rate of emergency medical services (EMS) dispatches in an urban setting.

METHODS

We performed an analysis of EMS data from New York City between years 2015-2019. Our outcome was hourly EMS dispatches, expressed as continuous data. Hours were split into derivation (75%) and validation (25%) datasets. Candidate variables included averages of prior rates, temporal and weather characteristics. We used a metalearner to evaluate and aggregate individual learners (generalized linear model, generalized additive model, random forest, multivariable adaptive regression splines, and extreme gradient boost). Four models were investigated: 1) temporal variables, 2) weather and temporal variables, and datasets in which weather data were lagged by 3) six and 4) twelve hours. In exploratory analyses, we constructed learners for high acuity and trauma encounters.

RESULTS

7,364,275 EMS dispatches occurred during the 43,823-hour period. When using temporal variables, the mean absolute error (MAE) rate was 11.5 dispatches in the validation dataset. These were slightly improved following incorporation of weather variables (MAE 11.3). When using 6- and 12-hour lagged weather variables, learners demonstrated lower accuracy (MAE 11.8 in 6-hour lagged datasets; 12.2 in 12-hour lagged dataset). All models had a coefficient of determination (R²) ≥0.91. The extreme gradient boosting and random forest learners were assigned the highest coefficients. In an investigation of variable importance, hour of day and average EMS dispatches over the previous six hours were the most important variables in both the extreme gradient boosting and random forest learners. The algorithm performed well at predicting frequently occurring peaks, with greater challenges at both extremes. Learners created high-acuity and for trauma-related encounters demonstrated superior MAE, but with lower R² in the validation cohort (MAE 6.9 and R² 0.84 for high acuity encounters; MAE 5.3 and R² 0.79 for trauma in learners using time and weather variables).

CONCLUSION

We developed an ensemble machine learning algorithm to predict EMS dispatches in an urban setting. These models demonstrated high accuracy, with MAEs <12 per hour in all. These algorithms may carry benefit in the real-time prediction of EMS responses, allowing for improved resource utilization.

Climatic factors are associated with asthma prevalence: An ecological study using English quality outcomes framework general practitioner practice data

Asthma is a complex disease with multiple environmental factors proposed to contribute to aetiology. Geographical analyses can shed light on the determinants of asthma. Ultraviolet radiation has been associated with asthma prevalence in past ecological studies. We have increased the detail of examining the association between asthma and ultraviolet radiation with addition of the variables of temperature, relative humidity and precipitation. An ecological study was designed to investigate meteorological factors associated with asthma prevalence in England. Data from the 2005 quality outcomes framework were used to determine the prevalence of asthma in primary care in England. This information was supplemented with indicators of obesity and smoking of the General Practitioner practice and population (by age and sex), deprivation and ethnicity at lower super output level from the 2001 and 2011 census. Annual mean meteorological data was attained from the Met Office and Joint Research Centre. We used a multiple linear regression to examine individual and multiple climatic factors through a principal components analysis. We tested for an association with asthma prevalence, after taking into account the spatial autocorrelation of the data. Asthma prevalence from general practice surgeries in England was 5.88% (95% CI 5.83 to 5.92). In the highest ultraviolet radiation weighted by the pre-vitamin D action spectrum (UV_vitd) quartile (2.12 to 2.50 kJ/m²/day), asthma had a 5% reduction in prevalence; compared to the lowest quartile here (0.95 (95% CI 0.92 to 0.98)). Similar reductions were found in the higher temperature 0.93 (95% CI 0.90 to 96). The opposite was found with relative humidity 1.09 (95% CI 1.05 to 1.12). A combination of high temperature and UVvitd highlighted postcode districts in the South East of England with a climate beneficial to low asthma prevalence. The South West of England represented a climate which had both beneficial and detrimental associations with asthma development. Climate is associated with asthma prevalence in England. Understanding the contribution of multiple climatic factors and the relationship with the indoor environment could help to explain the population distribution of asthma.

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.

Thunderstorm allergy and asthma: state of the art

Thunderstorm-triggered asthma (TA) can be defined as the occurrence of acute asthma attacks immediately following a thunderstorm during pollen seasons. Outbreaks have occurred across the world during pollen season with the capacity to rapidly inundate a health care service, resulting in potentially catastrophic outcomes for allergic patients. TA occurs when specific meteorological and aerobiological factors combine to affect predisposed atopic patients with IgE-mediated sentitization to pollen allergens. Thunderstorm outflows can concentrate aeroallergens, most commonly grass pollen but also other pollens such as Parietaria and moulds in TA, at ground level to release respirable allergenic particles after rupture by osmotic shock related to humidity and rainfall. Inhalation of high concentrations of these aeroallergens by sensitized individuals can induce early asthmatic responses which can be followed by a late inflammatory phase. There is evidence that, during pollen season, thunderstorms can induce allergic asthma outbreaks, sometimes also severe asthma crisis and sometimes deaths in patients suffering from pollen allergy. It has been observed that changes in the weather such as rain or humidity may induce hydratation of pollen grains during pollen seasons and sometimes also their fragmentation which generates atmospheric biological aerosols carrying allergens. Asthma attacks are induced for the high concentration at ground level of pollen grains which may release allergenic particles of respirable size after rupture by osmotic shock. In other words, it is a global health problem observed in several cities and areas of the world that can strike without sufficient warning, inducing sometimes severe clinical consequences also with deaths of asthma patients. Due to constant climate change, future TA events are likely to become more common, more disastrous and more unpredictable, as a consequence it is important to have deep knowledge on this topic to prevent asthma attacks. Other environmental factors, such as rapid changes in temperature and agricultural practices, also contribute to causing TA.

The Role of Extreme Weather and Climate-Related Events on Asthma Outcomes

Extreme weather and climate events are likely to increase in frequency and severity as a consequence of global climate change. These are events that can include flooding rains, prolonged heat waves, drought, wildfires, hurricanes, severe thunderstorms, tornadoes, storm surge, and coastal flooding. It is important to consider these events as they are not merely meteorologic occurrences but are linked to our health. We aim to address how these events are interconnected with asthma outcomes associated with thunderstorm asthma, pollen production, mold infestation from flooding events, and poor air quality during wildfires.

Epidemic Thunderstorm Asthma: Lessons Learned from the Storm Down-Under

Epidemic thunderstorm asthma (ETSA) is a global health problem that can strike without sufficient warning and can have catastrophic consequences. Because of climate change, future events are likely to become more common, more disastrous, and more unpredictable. To prevent loss of life and avoid surge events on health care infrastructure, identifying at-risk individuals and their potential biomarkers is the most prophylactic approach that can be taken to mitigate the deadly consequences of ETSA. In this review, we provide an update on the clinical mechanism, global prevalence, and characteristics of those patients moderately or severely at risk of ETSA. Identifying these patient characteristics will aid clinical professionals to provide suitable and personalized treatment plans and, in turn, avoid future loss of life.

Weather and temporal models for emergency medical services: An assessment of generalizability

BACKGROUND

Emergency medical services (EMS) response volume has been linked to weather and temporal factors in a regional EMS system. We aimed to identify if models of EMS utilization incorporating these data are generalizable through geographically disparate areas in the United States.

METHODS

We performed a retrospective analysis of EMS dispatch data from four regions: New York City, San Francisco, Cincinnati, and Marin County for years 2016-2019. For each model, we used local weather data summarized from the prior 6 h into hourly bins. Our outcome for each model was EMS dispatches as count data. We fit and optimized a negative binomial regression model for each region, to estimate incidence rate ratios. We compared findings to a prior study performed in Western Pennsylvania.

RESULTS

We included 5,940,637 EMS dispatches from New York City, 809,405 from San Francisco, 260,412 from Cincinnati, and 77,461 from Marin County. Models demonstrated consistency with the Western Pennsylvania model with respect to temperature, season, wind speed, dew point, and time of day; both in terms of direction and effect size when expressed as incidence rate ratios. Precipitation was associated with increasing dispatches in the New York City, Cincinnati, and Marin County models, but not the San Francisco model.

CONCLUSION

With minor differences, regional models demonstrated consistent associations between dispatches and time and weather variables. Findings demonstrate the generalizability of associations between these variables with respect to EMS use. Weather and temporal factors should be considered in predictive modeling to optimize EMS staffing and resource allocation.

Thunderstorm asthma: an overview of mechanisms and management strategies

INTRODUCTION

Epidemic thunderstorm asthma (ETSA) is due to a complex interaction of environmental and individual susceptibility factors, with outbreaks reported globally over the last four decades. Australia has been particularly susceptible with nearly half of episodes reported internationally, culminating in the catastrophic Melbourne 2016 event.

AREAS COVERED

Reported ETSA episodes are reviewed for common environmental and meteorological risk factors. Allergen aerobiology interaction with thunderstorm activity and rapid weather condition changes is examined. Assessment of the clinical and immunological data highlights risk factors for ETSA presentation, hospital admission, and intensive care admission. Risk factors associated with ETSA deaths are evaluated. Public health strategies, as well as pharmacological and immunological management approaches to reduce individual susceptibility and prevent ETSA are discussed.

EXPERT OPINION

Improved understanding of the specific meteorological factors predisposing to the greatest risk of ETSA to improve forecasting is required. Better monitoring of aeroallergen levels in areas of greatest geographic risk, with further research into allergen aerobiology underpinning mechanisms of allergen exposure is needed. The role of climate change in increasing the risk of ETSA outbreaks requires further research. Public awareness and education are required to reduce exposure, and to improve uptake of pharmacological and immunological risk reduction and preventive strategies.

The effects of climate change on respiratory allergy and asthma induced by pollen and mold allergens

The impact of climate change on the environment, biosphere, and biodiversity has become more evident in the recent years. Human activities have increased atmospheric concentrations of carbon dioxide (CO₂ ) and other greenhouse gases. Change in climate and the correlated global warming affects the quantity, intensity, and frequency of precipitation type as well as the frequency of extreme events such as heat waves, droughts, thunderstorms, floods, and hurricanes. Respiratory health can be particularly affected by climate change, which contributes to the development of allergic respiratory diseases and asthma. Pollen and mold allergens are able to trigger the release of pro-inflammatory and immunomodulatory mediators that accelerate the onset the IgE-mediated sensitization and of allergy. Allergy to pollen and pollen season at its beginning, in duration and intensity are altered by climate change. Studies showed that plants exhibit enhanced photosynthesis and reproductive effects and produce more pollen as a response to high atmospheric levels of carbon dioxide (CO₂ ). Mold proliferation is increased by floods and rainy storms are responsible for severe asthma. Pollen and mold allergy is generally used to evaluate the interrelation between air pollution and allergic respiratory diseases, such as rhinitis and asthma. Thunderstorms during pollen seasons can cause exacerbation of respiratory allergy and asthma in patients with hay fever. A similar phenomenon is observed for molds. Measures to reduce greenhouse gas emissions can have positive health benefits.

Natural history of asthma symptoms after epidemic thunderstorm asthma: a 3-year longitudinal study

Background

The world's most catastrophic epidemic thunderstorm asthma event (ETSA) affected Melbourne in 2016. Little is known about the natural history of individuals affected by such extreme events.

Objective

In this single center prospective 3-year longitudinal study, symptomatology and behaviors of individuals affected by ETSA were assessed.

Methods

Standardized telephone questionnaire was used to evaluate frequency of asthma symptoms, inhaled corticosteroid preventer use, asthma action plan ownership, and healthcare utilization. Questionnaires were administered at 12, 24, and 36 months after 2016 ETSA. Subgroup analyses of the ‘current’, ‘past’, ‘possible,’ and ‘no asthma’ subgroups were also conducted.

Results

Two hundred and eight, 164, and 112 completed questionnaires were analyzed in 2017, 2018, and 2019, respectively. Seventy to eighty five percent of respondents reported ongoing asthma symptoms in any given year, of which 20%–28% experienced weekly symptoms. Nearly 50% of respondents were prescribed preventers, with approximately 45% adherent at least 5 days a week. Less than 40% had an asthma action plan and 15%–20% sought urgent medical attention for asthma over the follow-up period. Among 106 individuals with 3 consecutive years of completed questionnaires, those with no prior doctor diagnosis of asthma were significantly more likely to be asymptomatic on follow-up than those with a prior doctor diagnosis of asthma (p = 0.02). Subgroup analyses suggest that large proportions of respondents with ‘past’ and ‘no asthma’ continue to remain symptomatic throughout the 36-month period.

Conclusion

In individuals affected by ETSA, we found evidence of ongoing loss of asthma control in those with previously well controlled asthma, and the persistence of symptoms suggestive of asthma in those with no history or symptoms suggestive of prior asthma, even after 36 months from initial ETSA. Low rates of inhaler adherence and asthma action plan ownership may contribute to increased morbidity and mortality from future ETSA events. Further research is required to confirm these findings.

Thunderstorm Asthma Epidemic-A Systematic Review of the General Practice Perspective

Thunderstorm asthma (TA) epidemics have been recognized globally as a rare phenomenon, producing a rapid surge of acute asthma presentations leading to an increased demand on emergency medical services and healthcare resources. General practitioners (GPs) are well placed in the community to contribute to healthcare during TA epidemics and similar disaster events. The aim of this review was to synthesize current evidence of the experiences of GPs during TA epidemics and similar surge events. A comprehensive systematic search of eleven electronic databases, including ancestry searching for peer-reviewed studies and grey literature published in English was conducted. Quantitative and qualitative study designs were included, and a quality assessment conducted. Of the 125 records identified, 16 were included for synthesis. During TA epidemics and surge events, GPs experience an increased demand for services, yet it is not known if general practice clinics experience resource limitations from this patient surge. While GPs express a willingness to help, few structures are in place to liaise, support and provide information to GPs during surge events. Following most surge/disaster events, no GP data is collected so it is not known how to improve coordination and communication between general practice services and emergency services. GPs have well-functioning adaptive management systems, and resources of space, supplies and staff thus the ability to increase surge capacity of their clinics.

A systematic review of the role of grass pollen and fungi in thunderstorm asthma

BACKGROUND

Thunderstorm asthma is defined as epidemics of asthma occurring shortly after a thunderstorm. While grass pollen has been implicated in thunderstorm asthma events, little is known about the role of fungi and studies have not been synthesised.

OBJECTIVE

This systematic review aims to evaluate whether grass pollen is necessary in thunderstorm asthma events and whether fungi also play a part in these associations.

METHODS

We conducted a systematic search using six electronic databases (i.e. CINAHL, Medline (Ovid), Web of Science, ProQuest Central, EMBASE and Google Scholar) and checked reference lists. The search terms used were pollen AND thunderstorm* AND asthma. The inclusion criteria were studies published in English with original human data relating to outdoor pollen and thunderstorm asthma.

RESULTS

Twenty of 2198 studies were eligible. Reported findings differed due to variation in methodological approaches and a meta-analysis was not possible. Nonetheless, of the 20 studies included, 15 demonstrated some relationship with nine demonstrating lagged effects up to four days for increasing grass pollen counts associated with increased risk of thunderstorm asthma. Of the 10 studies that examined fungi, nine demonstrated a positive relationship with thunderstorm asthma. The fungal taxa involved varied, depending on whether measurements were recorded before, during or after the thunderstorm. Nevertheless, none of the studies considered fungi as a potential effect modifier for the pollen-thunderstorm asthma association.

CONCLUSION

We found evidence to suggest that grass pollen was a necessary factor for thunderstorm asthma but there are other as yet unrecognised environmental factors that may also be important. Further research is required to examine the role of fungi and other environmental factors such as air quality as potential effect modifiers of the association.

Mechanisms and Management of Asthma Exacerbations

Acute asthma remains an important medical emergency, the most frequent cause of acute admissions in children and a major source of morbidity for adults with asthma. In all ages with asthma, the presence of exacerbations is an important defining characteristic of asthma severity. In this review, we assess the epidemiology of acute asthma, the triggers of acute exacerbations, and the mechanisms that underlie these exacerbations. We also assess current treatments that prevent exacerbations, with an emphasis on the role of type 2 airway inflammation in the context of acute exacerbations and the novel treatments that effectively target this. Finally we review current management strategies of the exacerbations themselves.

A Clean Air Plan for Sydney: An Overview of the Special Issue on Air Quality in New South Wales

This paper presents a summary of the key findings of the special issue of Atmosphere on Air Quality in New South Wales and discusses the implications of the work for policy makers and individuals. This special edition presents new air quality research in Australia undertaken by (or in association with) the Clean Air and Urban Landscapes hub, which is funded by the National Environmental Science Program on behalf of the Australian Government’s Department of the Environment and Energy. Air pollution in Australian cities is generally low, with typical concentrations of key pollutants at much lower levels than experienced in comparable cities in many other parts of the world. Australian cities do experience occasional exceedances in ozone and PM2.5 (above air pollution guidelines), as well as extreme pollution events, often as a result of bushfires, dust storms, or heatwaves. Even in the absence of extreme events, natural emissions play a significant role in influencing the Australian urban environment, due to the remoteness from large regional anthropogenic emission sources. By studying air quality in Australia, we can gain a greater understanding of the underlying atmospheric chemistry and health risks in less polluted atmospheric environments, and the health benefits of continued reduction in air pollution. These conditions may be representative of future air quality scenarios for parts of the Northern Hemisphere, as legislation and cleaner technologies reduce anthropogenic air pollution in European, American, and Asian cities. However, in many instances, current legislation regarding emissions in Australia is significantly more lax than in other developed countries, making Australia vulnerable to worsening air pollution in association with future population growth. The need to avoid complacency is highlighted by recent epidemiological research, reporting associations between air pollution and adverse health outcomes even at air pollutant concentrations that are lower than Australia’s national air quality standards. Improving air quality is expected to improve health outcomes at any pollution level, with specific benefits projected for reductions in long-term exposure to average PM2.5 concentrations.

Anatomy of a demand shock: Quantitative analysis of crowding in hospital emergency departments in Victoria, Australia during the 2009 influenza pandemic

Objective

An infectious disease outbreak such as the 2009 influenza pandemic is an unexpected demand shock to hospital emergency departments (EDs). We analysed changes in key performance metrics in (EDs) in Victoria during this pandemic to assess the impact of this demand shock.

Design and setting

Descriptive time-series analysis and longitudinal regression analysis of data from the Victorian Emergency Minimum Dataset (VEMD) using data from the 38 EDs that submit data to the state’s Department of Health and Human Services.

Main outcome measures

Daily number of presentations, influenza-like-illness (ILI) presentations, daily mean waiting time (time to first being seen by a doctor), daily number of patients who did-not-wait and daily number of access-blocked patients (admitted patients with length of stay >8 hours) at a system and hospital-level.

Results

During the influenza pandemic, mean waiting time increased by up to 25%, access block increased by 32% and did not wait presentations increased by 69% above pre-pandemic levels. The peaks of all three crowding variables corresponded approximately to the peak in admitted ILI presentations. Longitudinal fixed-effects regression analysis estimated positive and statistically significant associations between mean waiting times, did not wait presentations and access block and ILI presentations.

Conclusions

This pandemic event caused excess demand leading to increased waiting times, did-not-wait patients and access block. Increases in admitted patients were more strongly associated with crowding than non-admitted patients during the pandemic period, so policies to divert or mitigate low-complexity non-admitted patients are unlikely to be effective in reducing ED crowding.

Effects of Meteorological Factors on Hospitalizations in Adult Patients with Asthma: A Systematic Review

Background

Environmental factors such as weather variables contribute to asthma exacerbation. The impact of meteorological factors on asthma-related hospital admissions (HAs) or emergency department visits (EDVs) has been assessed in the literature. We conducted a systematic review to establish a conclusion of whether these findings from the literature are consistent and generalizable or if they vary significantly by certain subgroups.

Objective

This study aims to review the effect of meteorological variables on asthma HAs and EDVs in adults, to identify knowledge gaps and to highlight future research priorities.

Method

A systematic search was conducted in electronic databases such as PubMed, Embase, and CINAHL. All studies published in English were screened and included if they met the eligibility criteria. Two independent reviewers assessed the quality of the studies and extracted the data. The available evidence was summarized and presented using a harvest plot.

Results

Our initial search returned a total of 3887 articles. After screening titles, abstracts, and full texts, 16 studies were included. Thirty-one percent of the included studies (5/16) found that temperature was the only factor associated with asthma hospitalization or EDVs. Six studies (37%) found that both temperature and relative humidity were associated with HAs. Four studies (25%) identified thunderstorms as a possible factor associated with asthma hospitalization in adults.

Conclusion

Our review suggests that HAs and EDVs due to asthma are associated with many meteorological factors. Among the articles included in this review, changing temperature is the most commonly studied variable. We did not find studies that measured barometric pressure, weather phenomena, or the effect of tornados. To develop effective strategies to protect subjects at risk, further studies are required.

Thunderstorm-triggered asthma: what we know so far

Thunderstorm-triggered asthma (TA) is the occurrence of acute asthma attacks immediately following a thunderstorm. Epidemics have occurred across the world during pollen season and have the capacity to rapidly inundate a health care service, resulting in potentially catastrophic outcomes for patients. TA occurs when specific meteorological and aerobiological factors combine to affect predisposed patients. Thunderstorm outflows can concentrate aeroallergens, most commonly grass pollen in TA, at ground level to release respirable allergenic particles after rupture by osmotic shock related to humidity and rainfall. Inhalation of high concentrations of these aeroallergens by sensitized individuals can induce early asthmatic responses which are followed by a late inflammatory phase. Other environmental factors such as rapid temperature change and agricultural practices contribute to the causation of TA. The most lethal TA event occurred in Melbourne, Australia, in 2016. Studies on the affected individuals found TA to be associated with allergic rhinitis, ryegrass pollen sensitization, pre-existing asthma, poor adherence to inhaled corticosteroid preventer therapy, hospital admission for asthma in the previous year and outdoor location at the time of the storm. Patients without a prior history of asthma were also affected. These factors are important in extending our understanding of the etiology of TA and associated clinical indicators as well as possible biomarkers which may aid in predicting those at risk and thus those who should be targeted in prevention campaigns. Education on the importance of recognizing asthma symptoms, adherence to asthma treatment and controlling seasonal allergic rhinitis is vital in preventing TA. Consideration of allergen immunotherapy in selected patients may also mitigate risk of future TA. Epidemic TA events are predicted to increase in frequency and severity with climate change, and identifying susceptible patients and preventing poor outcomes is a key research and public health policy priority.

Weather and Temporal Factors Associated with Use of Emergency Medical Services

Background: Fluctuations in emergency medical services (EMS) responses can have a substantial impact on the ability of agencies to meet resource needs within an EMS system. We aimed to identify weather characteristics as potentially predictable factors associated with EMS responses. Methods: We reviewed hourly counts of scene responses documented by 24 EMS agencies in Western Pennsylvania from January 1, 2014 to December 31, 2017 and compared rates of responses to weather characteristics. Responses to counties nonadjacent to the studied weather reporting station and interfacility/scheduled transports were excluded. We identified the mean temperature, meters visibility, dew point, wind speed, total millimeters of precipitation, and presence of rain or snow in 6-hour windows prior to dispatch, in addition to temporal factors of time of day and weekend vs. weekday. Analysis was performed using multivariable linear regression of a negative binomial distribution, reporting incidence rate ratios (IRR) with 95% confidence intervals (CI). Secondary analyses were performed for transports to the hospital and cases involving transports for traumatic complaints and pediatric patients (age <18 years). Results: We included 529,058 responses (54.8% female, mean age 57.2 ± SD 24.7 years). In our multivariable model, responses were associated with (IRR, 95% CI) rain (1.10, 1.08-1.11) snow (1.07, 1.05-1.09), and both rain and snow (1.15, 1.11-1.19). A lower incidence of responses occurred on weekends (0.84, 0.83-0.85) and at night (0.62, 0.61-0.62). Increasing temperature in 5 °C increments was associated with an increase in responses across seasons with an effect that varied between 1.16 (1.15-1.17) in winter to 1.31 (1.28-1.33) in summer. Windy weather was associated with increased responses from light breeze (1.10, 1.09-1.11) to fresh breeze or greater (1.23, 1.16-1.30). Transports occurred in a similar pattern to responses. Trauma transports (n = 64,235) occurred more during weekends (1.04, 1.02-1.06). Pediatric transports (n = 21,880) were not significantly associated with precipitation or season. Conclusion: EMS responses increased with rising temperature and following rain and snow. These findings may assist in planning by EMS agencies and emergency departments to identify periods of greatest resource utilization.

Advances in the clinical and mechanism research of pollen induced seasonal allergic asthma

Seasonal allergic asthma prevalence has been increasing over the last decades and is one of global health concerns now. Pollen is one of the main reasons to cause seasonal allergic asthma and influenced by multiple risk factors. Thunderstorm-related asthma is a typical type of seasonal allergic asthma that thunderstorms occurring can induce severe asthma attacks during pollen season. The diagnosis of seasonal allergic asthma relies on precise medical history, skin prick tests (SPT) and specific IgE detection. Component resolved diagnosis is greatly significant in determining the complex situation. Allergen specific immunotherapy (AIT) is the only disease-modifying therapy that can change the natural course from seasonal allergic rhinitis to seasonal allergic asthma.

The 2016 Melbourne thunderstorm asthma epidemic: Risk factors for severe attacks requiring hospital admission

BACKGROUND

The world's most catastrophic and deadly thunderstorm asthma epidemic struck Melbourne, Australia, on November 21, 2016.

OBJECTIVE

Among thunderstorm-affected patients presenting to emergency rooms (ERs), we investigated risk factors predicting severe attacks requiring admission to hospital.

METHODS

Thunderstorm-affected patients were identified from ER records at the eight major Melbourne health services and interviewed by telephone. Risk factors for hospital admission were analyzed.

RESULTS

We interviewed 1435/2248 (64%) of thunderstorm-affected patients, of whom 164 (11.4%) required hospital admission. Overall, rhinitis was present in 87%, and current asthma was present in 28%. Odds for hospital admission were higher with increasing age (odds ratio 1.010, 95% CI 1.002, 1.019) and among individuals with current asthma (adjusted odds ratio [aOR] 1.87, 95% CI 1.26, 2.78). Prior hospitalization for asthma in the previous 12 months further increased the odds for hospital admission (aOR 3.16, 95% CI 1.63, 6.12). Among patients of Asian ethnicity, the odds for hospital admission were lower than for non-Asian patients (aOR 0.59, 95% CI 0.38, 0.94), but higher if born in Australia (OR = 5.42, 95% CI 1.56, 18.83).

CONCLUSIONS

In epidemic thunderstorm asthma patients who presented to the ER, higher odds for hospital admission among patients with known asthma were further amplified by recent asthma admission, highlighting the vulnerability conferred by suboptimal disease control. Odds for hospital admission were lower in Asian patients born overseas, but higher in Asian patients born locally, than in non-Asian patients; these observations suggest susceptibility to severe thunderstorm asthma may be enhanced by gene-environment interactions.

Epidemiology of Asthma in Children and Adults

Asthma is a globally significant non-communicable disease with major public health consequences for both children and adults, including high morbidity, and mortality in severe cases. We have summarized the evidence on asthma trends, environmental determinants, and long-term impacts while comparing these epidemiological features across childhood asthma and adult asthma. While asthma incidence and prevalence are higher in children, morbidity, and mortality are higher in adults. Childhood asthma is more common in boys while adult asthma is more common in women, and the reversal of this sex difference in prevalence occurs around puberty suggesting sex hormones may play a role in the etiology of asthma. The global epidemic of asthma that has been observed in both children and adults is still continuing, especially in low to middle income countries, although it has subsided in some developed countries. As a heterogeneous disease, distinct asthma phenotypes, and endotypes need to be adequately characterized to develop more accurate and meaningful definitions for use in research and clinical settings. This may be facilitated by new clustering techniques such as latent class analysis, and computational phenotyping methods are being developed to retrieve information from electronic health records using natural language processing (NLP) algorithms to assist in the early diagnosis of asthma. While some important environmental determinants that trigger asthma are well-established, more work is needed to define the role of environmental exposures in the development of asthma in both children and adults. There is increasing evidence that investigation into possible gene-by-environment and environment-by-environment interactions may help to better uncover the determinants of asthma. Therefore, there is an urgent need to further investigate the interrelationship between environmental and genetic determinants to identify high risk groups and key modifiable exposures. For children, asthma may impair airway development and reduce maximally attained lung function, and these lung function deficits may persist into adulthood without additional progressive loss. Adult asthma may accelerate lung function decline and increase the risk of fixed airflow obstruction, with the effect of early onset asthma being greater than late onset asthma. Therefore, in managing asthma, our focus going forward should be firmly on improving not only short-term symptoms, but also the long-term respiratory and other health outcomes.

The Melbourne epidemic thunderstorm asthma event 2016: an investigation of environmental triggers, effect on health services, and patient risk factors

BACKGROUND

A multidisciplinary collaboration investigated the world's largest, most catastrophic epidemic thunderstorm asthma event that took place in Melbourne, Australia, on Nov 21, 2016, to inform mechanisms and preventive strategies.

METHODS

Meteorological and airborne pollen data, satellite-derived vegetation index, ambulance callouts, emergency department presentations, and data on hospital admissions for Nov 21, 2016, as well as leading up to and following the event were collected between Nov 21, 2016, and March 31, 2017, and analysed. We contacted patients who presented during the epidemic thunderstorm asthma event at eight metropolitan health services (each including up to three hospitals) via telephone questionnaire to determine patient characteristics, and investigated outcomes of intensive care unit (ICU) admissions.

FINDINGS

Grass pollen concentrations on Nov 21, 2016, were extremely high (>100 grains/m³). At 1800 AEDT, a gust front crossed Melbourne, plunging temperatures 10°C, raising humidity above 70%, and concentrating particulate matter. Within 30 h, there were 3365 (672%) excess respiratory-related presentations to emergency departments, and 476 (992%) excess asthma-related admissions to hospital, especially individuals of Indian or Sri Lankan birth (10% vs 1%, p<0·0001) and south-east Asian birth (8% vs 1%, p<0·0001) compared with previous 3 years. Questionnaire data from 1435 (64%) of 2248 emergency department presentations showed a mean age of 32·0 years (SD 18·6), 56% of whom were male. Only 28% had current doctor-diagnosed asthma. 39% of the presentations were of Asian or Indian ethnicity (25% of the Melbourne population were of this ethnicity according to the 2016 census, relative risk [RR] 1·93, 95% CI 1·74-2·15, p <0·0001). Of ten individuals who died, six were Asian or Indian (RR 4·54, 95% CI 1·28-16·09; p=0·01). 35 individuals were admitted to an intensive care unit, all had asthma, 12 took inhaled preventers, and five died.

INTERPRETATION

Convergent environmental factors triggered a thunderstorm asthma epidemic of unprecedented magnitude, tempo, and geographical range and severity on Nov 21, 2016, creating a new benchmark for emergency and health service escalation. Asian or Indian ethnicity and current doctor-diagnosed asthma portended life-threatening exacerbations such as those requiring admission to an ICU. Overall, the findings provide important public health lessons applicable to future event forecasting, health care response coordination, protection of at-risk populations, and medical management of epidemic thunderstorm asthma.

FUNDING

None.

How Do Storms Affect Asthma?

PURPOSE OF REVIEW

There are observations in various geographical areas that thunderstorms occurring during pollen seasons can induce severe asthma attacks in pollinosis patients.

RECENT FINDINGS

An accredited hypothesis explaining the association between thunderstorms and asthma suggests that storms can concentrate pollen grains at ground level, which may then release allergenic particles of respirable size in the atmosphere after their imbibition of water and rupture by osmotic shock. During the first 20-30 min of a thunderstorm, patients affected by pollen allergy may inhale a high quantity of the allergenic material that is dispersed into the atmosphere as a bioaerosol of allergenic particles, which can induce asthmatic reactions, often severe. Subjects without asthma symptoms, but affected by seasonal rhinitis can also experience an asthma attack. A key message is that all subjects affected by pollen allergy should be alerted to the danger of being outdoors during a thunderstorm in the pollen season, as such events may be an important cause of severe asthma exacerbations. In light of these observations, it is useful to predict thunderstorms and thus minimize thunderstorm-related events. Patients with respiratory allergy induced by pollens and molds need to be informed about a correct therapeutic approach of bronchial asthma by inhalation, including the use of bronchodilators and inhaled corticosteroids. The purpose of this review is to focalize epidemiological, etiopathogenetic, and clinical aspects of thunderstorm-related asthma.