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.

Prevention of Allergic Asthma with Allergen Avoidance Measures and the Role of Exposome.

PURPOSE OF REVIEW: It is well known that combination of sensitization and exposure to inhaled environmental allergens is related to both the development and elicitation of symptoms of asthma and that avoidance of allergens would exert beneficial effects in the prevention and control of the disease. Other important factors include the relevance of other allergens, exposure to sensitizing agents also outside patient's home, exposure to irritants (like chemical air pollutants), and the involvement of the patient with a correct education. It is also likely that clinical phase of allergic airway disease and the degree of airways remodeling represent relevant factors for the clinical outcome of allergen avoidance procedure. We reviewed existing evidence on prevention of asthma through allergen avoidance. RECENT FINDINGS: The management of respiratory allergy is a complex strategy (including prevention, drugs, immunological, and educational interventions). In addition, it is difficult in real life to distinguish the efficacy of single interventions. However, a combined strategy is likely to produce clinical results. A combined strategy is likely to produce satisfactory management of asthma. Allergens are an important trigger factor for the development of symptoms of respiratory allergy, and avoidance measures are able to reduce allergen levels. It is likely that clinical phase of allergic airway disease and the degree of airways remodeling represents relevant factors for the clinical outcome of allergen avoidance procedures. Considering the management of respiratory allergy is a complex strategy; it is difficult in real life to distinguish the efficacy of single interventions. However, further studies better quantifying the effects of allergens are needed.

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.

Climate change, allergy and asthma, and the role of tropical forests.

BACKGROUND: Tropical forests cover less than 10 per cent of all land area (1.8 × 107 km2) and over half of the tropical-forest area (1.1 × 107 Km2) is represented by humid tropical forests (also called tropical rainforests). The Amazon basin contains the largest rainforest on Earth, almost 5.8 million km2, and occupies about 40% of South America; more than 60% of the basin is located in Brazil and the rest in Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname and Venezuela. Over the past decade the positive role of tropical rainforests in capturing large amounts of atmospheric carbon dioxide (CO2) has been demonstrated. In response to the increase in atmospheric CO2 concentration, tropical forests act as a global carbon sink. MAIN BODY: Accumulation of carbon in the tropical terrestrial biosphere strongly contributes to slowing the rate of increase of CO2 into the atmosphere, thus resulting in the reduction of greenhouse gas effect. Tropical rainforests have been estimated to account for 32-36% of terrestrial Net Primary Productivity (NPP) that is the difference between total forest photosynthesis and plant respiration. Tropical rainforests have been acting as a strong carbon sink in this way for decades. However, over the past years, increased concentrations of greenhouse gases, and especially CO2, in the atmosphere have significantly affected the net carbon balance of tropical rainforests, and have warmed the planet substantially driving climate changes through more severe and prolonged heat waves, variability in temperature, increased air pollution, forest fires, droughts, and floods. The role of tropical forests in mitigating climate change is therefore critical. Over the past 30 years almost 600,000 km2 have been deforested in Brazil alone due to the rapid development of Amazonia, this is the reason why currently the region is one of the 'hotspots' of global environmental change on the planet. CONCLUSION: Deforestation represents the second largest anthropogenic source of CO2 to the atmosphere, after fossil fuel combustion. There are many causes of deforestation, including socioeconomic and natural factors, such as clear-cutting for agriculture, ranching and development, unsustainable logging for timber, as well as droughts, fires and degradation due to climate change. About natural causes of forest degradation, in the context of the Amazon, the major agent of change in the forest ecosystem would most likely be decreased dry-season precipitation. Of the 23 global climate models employed by the Intergovernmental Panel on Climate Change (IPCC) in their 2007 report, 50-70% predict a substantial (above 20%) reduction of dry-season rainfall in eastern Amazonia under mid-range greenhouse gas emissions scenarios, 40% in central Amazonia and 20% in the west. While annual carbon emissions from fossil-fuel combustion have been continually increasing since 1960s, historical trends of deforestation and associated carbon emissions have remained poorly understood.