Two consecutive thunderstorm associated epidemics of asthma in the city of Melbourne. The possible role of rye grass pollen

Pollen and sub-pollen particles: External interactions shaping the allergic potential of pollen

Pollen allergies, such as allergic rhinitis, are triggered by exposure to airborne pollen. They are a considerable global health burden, with their numbers expected to rise in the coming decades due to the advent of climate change and air pollution. The relationships that exist between pollens, meteorological, and environmental conditions are complex due to a lack of clarity on the nature and conditions associated with these interactions; therefore, it is challenging to describe their direct impacts on allergenic potential clearly. This article attempts to review evidence pertaining to the possible influence of meteorological factors and air pollutants on the allergic potential of pollen by studying the interactions that pollen undergoes, from its inception to atmospheric traversal to human exposure. This study classifies the evidence based on the nature of these interactions as physical, chemical, source, and biological, thereby simplifying the complexities in describing these interactions. Physical conditions facilitating pollen rupturing for tree, grass, and weed pollen, along with their mechanisms, are studied. The effects of pollen exposure to air pollutants and their impact on pollen allergenic potential are presented along with the possible outcomes following these interactions, such as pollen fragmentation (SPP generation), deposition of particulate matter on pollen exine, and modification of protein levels in-situ of pollen. This study also delves into evidence on plant-based (source and biological) interactions, which could indirectly influence the allergic potential of pollen. The current state of knowledge, open questions, and a brief overview of future research directions are outlined and discussed. We suggest that future studies should utilise a multi-disciplinary approach to better understand this complex system of pollen interactions that occur in nature.

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.

Factors associated with aeroallergen testing among adults with asthma in a large health system

Background

Aeroallergen testing informs precision care for adults with asthma, yet the epidemiology of testing in this population remains poorly understood.

Objective

We sought to identify factors associated with receiving aeroallergen testing, the results of these tests, and subsequent reductions in exacerbation measures among adults with asthma.

Methods

We used electronic health record data to conduct a retrospective, observational cohort study of 30,775 adults with asthma who had an office visit with a primary care provider or an asthma specialist from January 1, 2017, to August 26, 2022. We used regression models to identify (1) factors associated with receiving any aeroallergen test and tests to 9 allergen categories after the index visit, (2) factors associated with positive test results, and (3) reductions in asthma exacerbation measures in the year after testing compared with before testing.

Results

Testing was received by 2201 patients (7.2%). According to multivariable models, receiving testing was associated with having any office visit with an allergy/immunology specialist during the study period (odds ratio [OR] = 91.3 vs primary care only [P < .001]) and having an asthma emergency department visit (OR = 1.62 [P = .004]) or hospitalization (OR = 1.62 [P = .03]) in the year before the index visit. Age 65 years or older conferred decreased odds of testing (OR = 0.74 vs age 18-34 years [P = .008]) and negative test results to 6 categories (P ≤ .04 for all comparisons). Black race conferred increased odds of testing (OR =1.22 vs White race [P = .01]) and positive test results to 8 categories (P < .04 for all comparisons). Exacerbation measures decreased after testing.

Conclusion

Aeroallergen testing was performed infrequently among adults with asthma and was associated with reductions in asthma exacerbation measures.

Environmental influences on childhood asthma: Climate change

Climate change is a key environmental factor for allergic respiratory diseases, especially in childhood. This review describes the influences of climate change on childhood asthma considering the factors acting directly, indirectly and with their amplifying interactions. Recent findings on the direct effects of temperature and weather changes, as well as the influences of climate change on air pollution, allergens, biocontaminants and their interplays, are discussed herein. The review also focusses on the impact of climate change on biodiversity loss and on migration status as a model to study environmental effects on childhood asthma onset and progression. Adaptation and mitigation strategies are urgently needed to prevent further respiratory diseases and human health damage in general, especially in younger and future generations.

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.

The phenomenon of thunderstorm asthma in Bavaria, Southern Germany: a statistical approach

Higher incidences of asthma during thunderstorms can pose a serious health risk. In this study, we estimate the thunderstorm asthma risk using statistical methods, with special focus on Bavaria, Southern Germany. In this approach, a dataset of asthma-related emergency cases for the study region is combined with meteorological variables and aeroallergen data to identify statistical relationships between the occurrence of asthma (predictand) and different environmental parameters (set of predictors). On the one hand, the results provide evidence for a weak but significant relationship between atmospheric stability indices and asthma emergencies in the region, but also show that currently thunderstorm asthma is not a major concern in Bavaria due to overall low incidences. As thunderstorm asthma can have severe consequences for allergic patients, the presented approach can be important for the development of emergency strategies in regions affected by thunderstorm asthma and under present and future climate change conditions.

Importance of allergen–environment interactions in epidemic thunderstorm asthma

Australia is home to one of the highest rates of allergic rhinitis worldwide. Commonly known as ‘hay fever’, this chronic condition affects up to 30% of the population and is characterised by sensitisation to pollen and fungal spores. Exposure to these aeroallergens has been strongly associated with causing allergic reactions and worsening asthma symptoms. Over the last few decades, incidences of respiratory admissions have risen due to the increased atmospheric concentration of airborne allergens. The fragmentation and dispersion of these allergens is aided by environmental factors like rainfall, temperature and interactions with atmospheric aerosols. Extreme weather parameters, which continue to become more frequent due to the impacts of climate change, have greatly fluctuated allergen concentrations and led to epidemic thunderstorm asthma (ETSA) events that have left hundreds, if not thousands, struggling to breathe. While a link exists between airborne allergens, weather and respiratory admissions, the underlying factors that influence these epidemics remain unknown. It is important we understand the potential threat these events pose on our susceptible populations and ensure our health infrastructure is prepared for the next epidemic.

Thunderstorms, Pollen, and Severe Asthma in a Midwestern, USA, Urban Environment, 2007-2018

BACKGROUND

Previous research has shown an association between individual thunderstorm events in the presence of high pollen, commonly called thunderstorm asthma, and acute severe asthma events, but little work has studied risk over long periods of time, using detailed measurements of storms and pollen.

METHODS

We estimated change in risk of asthma-related emergency room visits related to thunderstorm asthma events in the Minneapolis-St. Paul metropolitan area over the years 2007-2018. We defined thunderstorm asthma events as daily occurrence of two or more lightning strikes during high pollen periods interpolating weather and pollen monitor data and modeling lightning counts. We acquired daily counts of asthma-related emergency department visits from the Minnesota Hospital Association and used a quasi-Poisson time-series regression to estimate overall relative risk of emergency department visits during thunderstorm asthma events.

RESULTS

We observed a 1.047 times higher risk (95% CI:1.012,1.083) of asthma-related emergency department visits on the day of thunderstorm asthma event. Our findings are robust to adjustment for temperature, humidity, wind, precipitation, ozone, PM2.5, day of week, and seasonal variation in asthma cases. Occurrence of lightning alone or pollen alone showed no association with risk of severe asthma. A two-stage analysis combining individual zip code level results shows similar RR and we see no evidence of spatial correlation or spatial heterogeneity of effect.

DISCUSSION

Our results support an association between co-occurrence of lightning and pollen and risk of severe asthma events. Our approach incorporates lightning and pollen data and small-spatial area exposure and outcome counts.

Thunderstorm asthma in seasonal allergic rhinitis: The TAISAR study

BACKGROUND

Asthma epidemics associated with thunderstorms have had catastrophic effects on individuals and emergency services. Seasonal allergic rhinitis (SAR) is present in the vast majority of people who develop thunderstorm asthma (TA), but there is little evidence regarding risk factors for TA among the SAR population.

OBJECTIVE

We sought to identify risk factors for a history of TA and hospital presentation in a cohort of individuals with SAR.

METHODS

This multicenter study recruited adults from Melbourne, Australia, with a past diagnosis of TA and/or self-reported SAR. Clinical information, spirometry results, white blood cell count, ryegrass pollen-specific (RGP-sp) IgE concentration, and fractional exhaled nitric oxide were measured to identify risk factors for a history of TA in individuals with SAR.

RESULTS

From a total of 228 individuals with SAR, 35% (80 of 228) reported SAR only (the I-SAR group), 37% (84 of 228) reported TA symptoms but had not attended hospital for treatment (the O-TA group), and 28% (64 of 228) had presented to the hospital for TA (the H-TA group). All patients in the H-TA group reported a previous asthma diagnosis. Logistic regression analysis of factors associated with O-TA and H-TA indicated that lower FEV1 value and an Asthma Control Questionnaire score higher than 1.5 were associated with H-TA. Higher blood RGP-sp IgE concentration, eosinophil counts, and fractional exhaled nitric oxide level were significantly associated with both O-TA and H-TA. Receiver operating curve analysis showed an RGP-sp IgE concentration higher than 10.1 kU/L and a prebronchodilator FEV1 value of 90% or lower to be biomarkers of increased H-TA risk.

CONCLUSION

Clinical tests can identify risk of a history of TA in individuals with SAR and thereby inform patient-specific treatment recommendations.

Impact of Fungal Spores on Asthma Prevalence and Hospitalization

Despite making up a significant proportion of airborne allergens, the relationship between fungal spores and asthma is not fully explored. Only 80 taxa of fungi have so far been observed to exacerbate respiratory presentations, with Cladosporium spp., Aspergillus spp., Penicillium spp., and Alternaria spp. found to comprise the predominant allergenic airborne spores. Fungal spores have been found in indoor environments, such as hospitals and housing due to poor ventilation. Meanwhile, outdoor fungal spores exhibit greater diversity, and higher abundance and have been associated with hospitalizations from acute asthma presentations. In addition, fungal spores may be the underlying, and perhaps the “missing link”, factor influencing the heightened rate of asthma presentations during epidemic thunderstorm asthma events. To improve our knowledge gap on fungal spores, airborne allergen monitoring must be improved to include not only dominant allergenic fungi but also provide real-time data to accurately and quickly warn the general public. Such data will help prevent future asthma exacerbations and thus save lives. In this review, we examine the health risks of prominent allergenic fungal taxa, the factors influencing spore dispersal and distribution, and why improvements should be made to current sampling methods for public health and wellbeing.

A systematic review of the effects of temperature and precipitation on pollen concentrations and season timing, and implications for human health

Climate and weather directly impact plant phenology, affecting airborne pollen. The objective of this systematic review is to examine the impacts of meteorological variables on airborne pollen concentrations and pollen season timing. Using PRISMA methodology, we reviewed literature that assessed whether there was a relationship between local temperature and precipitation and measured airborne pollen. The search strategy included terms related to pollen, trends or measurements, and season timing. For inclusion, studies must have conducted a correlation analysis of at least 5 years of airborne pollen data to local meteorological data and report quantitative results. Data from peer-reviewed articles were extracted on the correlations between seven pollen indicators (main pollen season start date, end date, peak date, and length, annual pollen integral, average daily pollen concentration, and peak pollen concentration), and two meteorological variables (temperature and precipitation). Ninety-three articles were included in the analysis out of 9,679 articles screened. Overall, warmer temperatures correlated with earlier and longer pollen seasons and higher pollen concentrations. Precipitation had varying effects on pollen concentration and pollen season timing indicators. Increased precipitation may have a short-term effect causing low pollen concentrations potentially due to "wash out" effect. Long-term effects of precipitation varied for trees and weeds and had a positive correlation with grass pollen levels. With increases in temperature due to climate change, pollen seasons for some taxa in some regions may start earlier, last longer, and be more intense, which may be associated with adverse health impacts, as pollen exposure has well-known health effects in sensitized individuals.

Managing Exacerbations in Thunderstorm Asthma: Current Insights

Epidemic thunderstorm asthma (ETSA) occurs following a thunderstorm due to the interaction of environmental and immunologic factors. Whilst first reported in the 1980s, the world's largest event in Melbourne, Australia, on November 21, 2016 has led to a wealth of clinical literature seeking to identify its mechanisms, susceptibility risk factors, and management approaches. Thunderstorm asthma (TA) typically presents during an aeroallergen season in individuals sensitized to perennial rye grass pollen (RGP) in Australia, or fungus in the United Kingdom, in combination with meteorological factors such as thunderstorms and lightning activity. It is now well recognized that large pollen grains, which usually lodge in the upper airway causing seasonal allergic rhinitis (SAR), are ruptured during these events, leading to sub-pollen particles respirable to the lower respiratory tract causing acute asthma. The identified risk factors of aeroallergen sensitization, specifically to RGP in Australians with a history of SAR, and individuals born in Australia of South-East Asian descent as a risk factor for TA has been key in selecting appropriate patients for preventative management. Moreover, severity-determining risk factors for ETSA-related asthma admission or mortality, including pre-existing asthma or prior hospitalization, poor inhaled corticosteroid adherence, and outdoor location at the time of the storm are important in identifying those who may require more aggressive treatment approaches. Basic treatments include optimizing asthma control and adherence to inhaled corticosteroid therapy, treatment of SAR, and education regarding TA to increase recognition of at-risk days. Precision treatment approaches may be more beneficial in select individuals, including the use of allergen immunotherapy and even biologic treatment to mitigate asthma severity. Finally, we discuss the importance of environmental health literacy in the context of concerns surrounding the increased frequency of ETSA due to climate change and its implications for the frequency and severity of future events.

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.

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.

Are convergence lines associated with high asthma presentation days? A case-control study in Melbourne, Australia

BACKGROUND

In epidemic thunderstorm asthma (ETSA) events a large number of people develop asthma symptoms over a short period of time. This is thought to occur because of a unique combination of high amounts of pollen and certain meteorological conditions. However, the exact cause and mechanism of epidemic thunderstorm asthma remains unclear.

OBJECTIVES

The objective of this study was to test the hypothesis that convergence lines may be a causative factor in ETSA events, by investigating whether convergence line weather events are associated with the occurrence of high asthma presentations days during the Victorian grass pollen season (October-December).

METHODS

A case control method was used. All public hospitals within 75 km of the Melbourne weather radar were included, and data were taken from 2009 to 2017 during the Victorian grass pollen season. Cases hospital days were hospitals with a high number of asthma presentations within a 24-h period, and controls were hospitals with an expected number of asthma presentations. Exposure was defined as geographical proximity of a convergence line to the hospital case or control.

RESULTS

Eighty-one case hospital days and 157 hospital day controls were included in the study. The odds of exposure to a convergence line were significantly higher for cases than for controls at all exposure distances. At 4 km, 80 of the 81 cases had been exposed to a convergence line.

CONCLUSION

Convergence lines appear to be a necessary, but not sufficient, element in the cause of epidemic thunderstorm asthma. This is the first study to show a clear link between epidemic thunderstorm asthma and convergence lines.

Thunderstorm Asthma: Looking Back and Looking Forward

Epidemic thunderstorm asthma has been reported to have occurred around twenty times over the past three decades in locations around the world. Thunderstorm asthma events are characterized by a significant increase in asthma presentations, which on occasion can overwhelm local medical services and result in fatalities. This review article presents the epidemiological data underpinning previous thunderstorm asthma events and analyzes what is known about the etiology of this unusual phenomenon. The evidence behind published risk factors, both at the individual and population level, is discussed. Research from the fields of allergy, pulmonology, meteorology, and climatology is drawn together and critically reviewed to surmise future predictions regarding thunderstorm asthma episodes. Finally, evidence-based individual, community, and environmentally targeted preventive strategies are presented.

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

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

Thunderstorm asthma epidemic - management challenges experienced by general practice clinics

OBJECTIVES

To understand the challenges faced by general practice (GP) services in terms of personnel, materials, secondary support services, and discharge and communication obstacles during the thunderstorm asthma (TA) epidemic in 2016.

METHODS

Qualitative study using semi-structured interviews and focus groups between September and October 2017. Participants were general practitioners (GPs), practice nurses, and administrative staff working on the TA epidemic days in the northern region of Melbourne, Australia.

RESULTS

18 participants contributed to the study from six clinic sites. Both daytime and evening clinics experienced a surge in respiratory patient presentations. After-hours clinics were inundated with asthma patients during the night of the thunderstorm. Consistent themes emerged about the challenges encountered by participants the most significant being limitation of medication, equipment, space, and personnel. The extraordinary influx of patients necessitated participants innovate solutions including recycling equipment, procuring medications from hospitals and community pharmacies, triage, altering management strategies and extending clinic hours. Participants were limited by the paucity of information from local services during the TA epidemic.

CONCLUSION

This study supports the view that GP services made a substantial contribution to the emergency response on the evening of the TA epidemic that occurred in Melbourne in 2016. Demands on resources were considerable during and after the epidemic yet GP staff showed great resilience increasing clinic surge capacity. Our findings indicate significant barriers at an organizational level including resource limitations, inadequate operational information, and the absence of timely communication channels that impaired the response of GP services during a TA event.

Thunderstorm asthma: revealing a hidden at-risk population

BACKGROUND

Epidemic thunderstorm asthma (ETSA) refers to large-scale acute bronchospasm events associated with thunderstorm. The most serious episode ever recorded occurred in Melbourne, Australia, in November 2016, where more than 3500 patients were treated in hospitals and 10 died. Previous work has been focused primarily on patient presentations to emergency departments. The prevalence of individuals with milder, non-emergent symptoms and who may be at risk of more serious episodes in the future has not previously been explored.

AIM

To characterise the nature and extent of respiratory symptoms in healthcare workers during the Melbourne ETSA event.

METHODS

A survey was conducted among staff and volunteers across Eastern Health, distributed on the intranet homepage, by email and by word of mouth. Anonymous survey questions were constructed to assess prior and current diagnoses of relevance, symptoms, and demography.

RESULTS

There were 515 participants (80% female, n = 411) of approximately 9000 potential respondents (~6% response rate) who completed the survey; 132 (25.6%) had symptoms suggestive of asthma during the Melbourne ETSA event, the majority of whom did not seek professional medical help. Notably, of those with ETSA-like symptoms, only 58 (43.9%) had a history of asthma, while 97 (73.5%) had a history of allergic rhinitis. Specifically, a history of allergic rhinitis (OR 2.77, P < 0.001), a history of asthma (OR 1.67, P = 0.037) and being of self-identified Asian ethnicity (OR 3.24, P < 0.001) were all strong predictors of ETSA-like symptoms. Being predominantly indoors was not protective.

CONCLUSIONS

Our study provides evidence of the presence of a large cohort of sufferers during the Melbourne ETSA event of 2016 that did not come to the attention of medical services, implying a potentially hidden and significant susceptible population. Further research should help clarify the true prevalence of vulnerability in the general population, with important public health implications.

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.

Beta-blocker use is an independent risk factor for thunderstorm asthma

OBJECTIVE

To identify risk factors for thunderstorm asthma (TA) in subjects ≥15 years of age from information available in routine clinical records.

METHODS

Retrospective and hospital-based case-control study of various clinical factors in all TA cases (n = 53) who presented to a single-site ED in November 2016 (TA16) and in a control group of patients (n = 156) who presented to the same ED with asthma during the pollen season over eight non-TA years. Bivariate analysis and multivariable logistic regression modelling was performed to calculate the odds of TA asthma in the presence of potential risk factors.

RESULTS

A logistic regression model revealed that the odds of TA were lower for age (odds ratio [OR] 0.97, 95% confidence interval [CI] 0.95-0.99), higher for Asian country of birth (OR 4.09, 95% CI 1.40-11.95) and higher for oral beta-blocker use (OR 6.43, 95% CI 1.58-26.33) compared to controls. No difference was found between TA16 cases and controls for allergies (to medication, grass pollen, animal), hayfever, smoking, oral non-steroidal anti-inflammatory drugs, or aspirin. Newly diagnosed asthma was higher in TA16 cases versus controls (32.1% vs 12.2%, P = 0.001).

CONCLUSIONS

Oral beta-blocker medications, younger age and Asian-born heritage are risk factors for TA. Further study is required to explore the potential association between beta-blockers and TA.

Evaluating the Risk of Epidemic Thunderstorm Asthma: Lessons from Australia

Epidemic thunderstorm asthma (ETA) is an emerging public health threat in Australia, highlighted by the 2016 event in Melbourne, Victoria, that overwhelmed health services and caused loss of life. However, there is limited understanding of the regional variations in risk. We evaluated the public health risk of ETA in the nearby state of Tasmania by quantifying the frequency of potential ETA episodes and applying a standardized natural disaster risk assessment framework. Using a case⁻control approach, we analyzed emergency presentations in Tasmania's public hospitals from 2002 to 2017. Cases were defined as days when asthma presentations exceeded four standard deviations from the mean, and controls as days when asthma presentations were less than one standard deviation from the mean. Four controls were randomly selected for each case. Independently, a meteorologist identified the dates of potential high-risk thunderstorm events. No case days coincided with thunderstorms during the study period. ETA was assessed as a very low risk to the Tasmanian population, with these findings informing risk prioritization and resource allocation. This approach may be scaled and applied in other settings to determine local ETA risk. Furthermore, the identification of hazards using this method allows for critical analysis of existing public health systems.

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.

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.

IL-21 alleviates allergic asthma in DOCK8-knockout mice

Patients with DOCK8 deficiency are at increased susceptibility to develop allergic diseases such as food allergy and asthma. Here, we aimed to analyze the pathogenesis of asthma in DOCK8-deficient patients. In our mouse model, DOCK8-knockout (KO) mice sensitized with low-dose OVA were challenged with 1.5% OVA to induce allergic asthma. As compared to that in WT mice, remarkable airway hyperresponsiveness was observed in KO mice. Increased inflammatory cells and eosinophils infiltrated in airway lumen in KO mice especially around bronchi. KO mice showed higher levels of serum IgE and OVA-specific IgE and significantly elevated IgE-producing B cells in blood and in spleen. Surprisingly, nasal administration with rmIL-21 significantly reduced the airway hyperresponsiveness, inflammatory infiltration, as well as the serum IgE and IgE-producing B cells. DOCK8-knockout mice are susceptible to low-dose OVA induced allergic airway inflammation and airway hyperresponsiveness. Supplementary nasal administration of rmIL-21 alleviates allergic asthma in this mouse model.

Seasonal asthma in Melbourne, Australia, and some observations on the occurrence of thunderstorm asthma and its predictability

We examine the seasonality of asthma-related hospital admissions in Melbourne, Australia, in particular the contribution and predictability of episodic thunderstorm asthma. Using a time-series ecological approach based on asthma admissions to Melbourne metropolitan hospitals, we identified seasonal peaks in asthma admissions that were centred in late February, June and mid-November. These peaks were most likely due to the return to school, winter viral infections and seasonal allergies, respectively. We performed non-linear statistical regression to predict daily admission rates as functions of the seasonal cycle, weather conditions, reported thunderstorms, pollen counts and air quality. Important predictor variables were the seasonal cycle and mean relative humidity in the preceding two weeks, with higher humidity associated with higher asthma admissions. Although various attempts were made to model asthma admissions, none of the models explained substantially more variation above that associated with the annual cycle. We also identified a list of high asthma admissions days (HAADs). Most HAADs fell in the late-February return-to-school peak and the November allergy peak, with the latter containing the greatest number of daily admissions. Many HAADs in the spring allergy peak may represent episodes of thunderstorm asthma, as they were associated with rainfall, thunderstorms, high ambient grass pollen levels and high humidity, a finding that suggests thunderstorm asthma is a recurrent phenomenon in Melbourne that occurs roughly once per five years. The rarity of thunderstorm asthma events makes prediction challenging, underscoring the importance of maintaining high standards of asthma management, both for patients and health professionals, especially during late spring and early summer.

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.

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

OBJECTIVES

To describe the demand for emergency medical assistance during the largest outbreak of thunderstorm asthma reported globally, which occurred on 21 November 2016.

DESIGN

A time series analysis was conducted of emergency medical service caseload between 1 January 2015 and 31 December 2016. Demand during the thunderstorm asthma event was compared to historical trends for the overall population and across specific subgroups.

SETTING

Victoria, Australia.

MAIN OUTCOME MEASURES

Number of overall cases attended by emergency medical services, and within patient subgroups.

RESULTS

On 21 November 2016, the emergency medical service received calls for 2954 cases, which was 1014 more cases than the average over the historical period. Between 6 pm and midnight, calls for 1326 cases were received, which was 2.5 times higher than expected. A total of 332 patients were assessed by paramedics as having acute respiratory distress on 21 November, compared with a daily average of 52 during the historical period. After adjustment for temporal trends, thunderstorm asthma was associated with a 42% (95% confidence interval 40% to 44%) increase in overall caseload for the emergency medical service and a 432% increase in emergency medical attendances for acute respiratory distress symptoms. Emergency transports to hospital increased by 17% (16% to 19%) and time critical referrals from general practitioners increased by 47% (21% to 80%). Large increases in demand were seen among patients with a history of asthma and bronchodilator use. The incidence of out-of-hospital cardiac arrest increased by 82% (67% to 99%) and pre-hospital deaths by 41% (29% to 55%).

CONCLUSIONS

An unprecedented outbreak of thunderstorm asthma was associated with substantial increase in demand for emergency medical services and pre-hospital cardiac arrest. The health impact of future events may be minimised through use of preventive measures by patients and predictive early warning systems.

An epidemic of thunderstorm asthma in Melbourne 2016: asthma, rhinitis, and other previous allergies

Background

On 21st November 2016, Melbourne experienced an epidemic of ‘thunderstorm asthma.’ Although previously described in the literature, risk factors and natural history remain incompletely understood.

Objective

Our aim was to follow up those presenting to the 3 Emergency Departments (EDs) in our health service during the epidemic, and assess their history for previous asthma, rhinitis, and allergies.

Methods

ED notes of all respiratory presentations within 48 hours of the thunderstorm event were reviewed and patients with acute asthma included. A standardised questionnaire was devised encompassing asthma diagnosis, undiagnosed asthma symptoms and rhinitis severity. Patients were contacted by phone within 30 days of the event.

Results

Three hundred forty-four patients were identified overall; 263 patients were contactable and completed a phone or mail questionnaire. The mean age was 32.7 ± 19.2 years (range, 6 months–87 years; 25% < 18 years) with 58% male sex. A previous diagnosis of asthma was present in 42% (n = 111), and there was no previous asthma diagnosis in 58% (n = 152). Of those who had no asthma diagnosis 53% had probable undiagnosed asthma. Overall, rhinitis prevalence was 88%, of which 72% were moderate or severe (Allergic Rhinitis and its Impact on Asthma guidelines) and 51% (n = 133) reported a history of grass pollen allergy.

Conclusion

Our data highlights the importance of atopy and rhinitis as risk factors for epidemic thunderstorm asthma. Better identification of undiagnosed asthma, and implementing treatment of asthma and rhinitis may be important.

Who's at risk of thunderstorm asthma? The ryegrass pollen trifecta and lessons learnt from the Melbourne thunderstorm epidemic

The Melbourne thunderstorm asthma epidemic in November 2016 was unprecedented in scale and impact. We systematically reviewed our hospital's patients with thunderstorm asthma to identify key risk factors. Of 85 adult patients assessed, the majority (60%) had no prior diagnosis of asthma. However, allergic rhinitis during the grass pollen season was almost universal (99%), as were ryegrass pollen sensitization (100%) and exposure to the outdoor environment during the thunderstorm (94%). Airborne pollen levels on the thunderstorm day were extreme. We conclude that ryegrass pollen sensitization, clinical allergic rhinitis, and acute allergen exposure constitute a risk-factor 'trifecta' for thunderstorm asthma.

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.

Climate change, air pollution, and allergic respiratory diseases: an update

PURPOSE OF REVIEW

The rising trend in prevalence of allergic respiratory disease and bronchial asthma, observed over the last decades, can be explained by changes occurring in the environment, with increasing presence of biologic, such as allergens, and chemical atmospheric trigger factors able to stimulate the sensitization and symptoms of these diseases.

RECENT FINDINGS

Many studies have shown changes in production, dispersion, and allergen content of pollen and spores because of climate change with an increasing effect of aeroallergens on allergic patients.

SUMMARY

Over the last 50 years, global earth's temperature has markedly risen likely because of growing emission of anthropogenic greenhouse gas concentrations. Major changes involving the atmosphere and the climate, including global warming induced by human activity, have a major impact on the biosphere and human environment.Urbanization and high levels of vehicle emissions are correlated to an increase in the frequency of pollen-induced respiratory allergy prevalent in people who live in urban areas compared with those who live in rural areas. Measures of mitigation need to be applied for reducing future impacts of climate change on our planet, but until global emissions continue to rise, adaptation to the impacts of future climate variability will also be required.

Allergen Avoidance in Allergic Asthma

Allergic asthma is the most frequent disease among the chronic respiratory disorders in pediatric age with an important social impact. In the last years, many efforts have been made to identify effective preventive approaches to get a better control of symptoms and to obtain the best future outcomes for the patients. In patients with allergic asthma triggered by the exposure to indoor allergens, the avoidance is the first intervention to prevent the appearance or the worsening of bronchial symptoms. This review article summarized the most recent evidence from literature about the efficacy of specific control interventions for the most important allergens. Even if a wide spectrum of interventions has been suggested and may help to reduce exposure to trigger allergy for sensitized patients suffering from respiratory allergy, evidence supporting the efficacy of these approaches is still weak and subject of controversy. However, the exposure control to specific airborne allergens is still widely recommended and may be effective as part of a holistic approach to reduce the severity of allergic respiratory symptoms in sensitized individuals.

Thunderstorm-related asthma: what happens and why

The fifth report issued by the Intergovernmental Panel on Climate Change forecasts that greenhouse gases will increase the global temperature as well as the frequency of extreme weather phenomena. An increasing body of evidence shows the occurrence of severe asthma epidemics during thunderstorms in the pollen season, in various geographical zones. The main hypotheses explaining association between thunderstorms and asthma claim that thunderstorms can concentrate pollen grains at ground level which may then release allergenic particles of respirable size in the atmosphere after their rupture by osmotic shock. During the first 20-30 min of a thunderstorm, patients suffering from pollen allergies may inhale a high concentration of the allergenic material that is dispersed into the atmosphere, which in turn can induce asthmatic reactions, often severe. Subjects without asthma symptoms, but affected by seasonal rhinitis can also experience an asthma attack. 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 exacerbations. In light of these observations, it is useful to predict thunderstorms and thus minimize thunderstorm-related events.

Differences in grass pollen allergen exposure across Australia

Objective: Allergic rhinitis and allergic asthma are important chronic diseases posing serious public health issues in Australia with associated medical, economic, and societal burdens. Pollen are significant sources of clinically relevant outdoor aeroallergens, recognised as both a major trigger for, and cause of, allergic respiratory diseases. This study aimed to provide a national, and indeed international, perspective on the state of Australian pollen data using a large representative sample.

Methods: Atmospheric grass pollen concentration is examined over a number of years within the period 1995 to 2013 for Brisbane, Canberra, Darwin, Hobart, Melbourne, and Sydney, including determination of the ‘clinical’ grass pollen season and grass pollen peak.

Results: The results of this study describe, for the first time, a striking spatial and temporal variability in grass pollen seasons in Australia, with important implications for clinicians and public health professionals, and the Australian grass pollen‐allergic community.

Conclusions: These results demonstrate that static pollen calendars are of limited utility and in some cases misleading. This study also highlights significant deficiencies and limitations in the existing Australian pollen monitoring and data.

Implications: Establishment of an Australian national pollen monitoring network would help facilitate advances in the clinical and public health management of the millions of Australians with asthma and allergic rhinitis.

Allergen-induced airway responses

Environmental allergens are an important cause of asthma and can contribute to loss of asthma control and exacerbations. Allergen inhalation challenge has been a useful clinical model to examine the mechanisms of allergen-induced airway responses and inflammation. Allergen bronchoconstrictor responses are the early response, which reaches a maximum within 30 min and resolves by 1-3 h, and late responses, when bronchoconstriction recurs after 3-4 h and reaches a maximum over 6-12 h. Late responses are followed by an increase in airway hyperresponsiveness. These responses occur when IgE on mast cells is cross-linked by an allergen, causing degranulation and the release of histamine, neutral proteases and chemotactic factors, and the production of newly formed mediators, such as cysteinyl leukotrienes and prostaglandin D2. Allergen-induced airway inflammation consists of an increase in airway eosinophils, basophils and, less consistently, neutrophils. These responses are mediated by the trafficking and activation of myeloid dendritic cells into the airways, probably as a result of the release of epithelial cell-derived thymic stromal lymphopoietin, and the release of pro-inflammatory cytokines from type 2 helper T-cells. Allergen inhalation challenge has also been a widely used model to study potential new therapies for asthma and has an excellent negative predictive value for this purpose.

Meteorological conditions, climate change, new emerging factors, and asthma and related allergic disorders. A statement of the World Allergy Organization

The prevalence of allergic airway diseases such as asthma and rhinitis has increased dramatically to epidemic proportions worldwide. Besides air pollution from industry derived emissions and motor vehicles, the rising trend can only be explained by gross changes in the environments where we live. The world economy has been transformed over the last 25 years with developing countries being at the core of these changes. Around the planet, in both developed and developing countries, environments are undergoing profound changes. Many of these changes are considered to have negative effects on respiratory health and to enhance the frequency and severity of respiratory diseases such as asthma in the general population.

Increased concentrations of greenhouse gases, and especially carbon dioxide (CO₂), in the atmosphere have already warmed the planet substantially, causing more severe and prolonged heat waves, variability in temperature, increased air pollution, forest fires, droughts, and floods – all of which can put the respiratory health of the public at risk. These changes in climate and air quality have a measurable impact not only on the morbidity but also the mortality of patients with asthma and other respiratory diseases. The massive increase in emissions of air pollutants due to economic and industrial growth in the last century has made air quality an environmental problem of the first order in a large number of regions of the world. A body of evidence suggests that major changes to our world are occurring and involve the atmosphere and its associated climate. These changes, including global warming induced by human activity, have an impact on the biosphere, biodiversity, and the human environment. Mitigating this huge health impact and reversing the effects of these changes are major challenges.

This statement of the World Allergy Organization (WAO) raises the importance of this health hazard and highlights the facts on climate-related health impacts, including: deaths and acute morbidity due to heat waves and extreme meteorological events; increased frequency of acute cardio-respiratory events due to higher concentrations of ground level ozone; changes in the frequency of respiratory diseases due to trans-boundary particle pollution; altered spatial and temporal distribution of allergens (pollens, molds, and mites); and some infectious disease vectors. According to this report, these impacts will not only affect those with current asthma but also increase the incidence and prevalence of allergic respiratory conditions and of asthma. The effects of climate change on respiratory allergy are still not well defined, and more studies addressing this topic are needed. Global warming is expected to affect the start, duration, and intensity of the pollen season on the one hand, and the rate of asthma exacerbations due to air pollution, respiratory infections, and/or cold air inhalation, and other conditions on the other hand.

An overview of thunderstorm-associated asthma outbreak in southwest of Iran

The aim of this study was to report the characteristics and treatment strategies of all patients with acute bronchospasm who were presented to the emergency departments of Ahvaz, Iran, following the occurrence of a thunderstorm on November 2, 2013. A total of 2000 patients presenting with asthma attacks triggered by thunderstorm were interviewed and an initial questionnaire was completed for each individual. After twenty days, patients were asked to complete a supplementary questionnaire, but only 800 of them accepted to do so. The majority of subjects was aged 20–40 years (60.5%) and had no history of asthma in most cases (60.0%). The symptoms had started outdoors for 60.0% of the participants. In most patients, the onset of the condition was on November 2. Short-acting β₂-agonist (salbutamol) and aminophylline were the most commonly prescribed medications in the emergency department. Upon the second interview, 85.3% of the patients were still symptomatic. Overall, 63.6% did not have a follow-up visit after hospital discharge, although all of them were referred to the specialist. The findings of the present study suggest that thunderstorm-associated asthma could affect young adults with no gender priority, with or without asthma history, which put a strain on emergency medical services.