On the occasion of World Meteorological Day 23 March 2021, the European Academy of Allergy Asthma and Clinical Immunology (EAACI), the European Federation of Allergy and Airways Diseases Patients’ Associations (EFA), and the World Meteorological Organisation (WMO) are joint in the global challenge of tackling climate change, mitigating its health-related impacts towards the enhancement of patients’ quality of life.
Air pollution shortens the lives of around 7 million people each year, and nine out of 10 people breathe air polluted by traffic emissions, industry, agriculture or incineration, according to WHO.
WHO estimates that by 2050, half of the world’s population will be affected by asthma and allergy. Human-caused climatic change strongly contributes to this rising frequency through direct and indirect effects.
Weather changes may affect the airways directly by cooling or irritation. Exacerbations of asthma and rhinitis have been shown to be precipitated by low temperature and humidity or by a sudden fall in temperature. Asthma admissions increase following low or high barometric pressure and rainfall.
Climate change is also a huge threat to the well-being of patients with asthma and allergy through increased exposure to risk factors, namely through worsening ambient air pollution and altered local and regional pollen production, mould proliferation and biodiversity loss. The pattern of the effects varies regionally depending on latitude, altitude, rainfall and storms, land-use patterns, urbanisation, transportation, and energy production.
Increased air pollution. Significant variations in the temperature, humidity, wind, and precipitations that accompany climate change profoundly impact air quality via modifications in the transport, dispersion, and conversion of air pollutants. Atmospheric warming increases ground-level ozone in many regions. Related phenomena – urbanisation, perturbed ventilation and increased confinement indoors, wildfires and sandstorms, – are at the origin of worsening of gas and particulate matter (PM) exposure. All these events put individuals at an elevated risk of exposure to polluted air, resulting in the development or aggravation of asthma and allergic diseases.
It is well established that air pollution exposure, especially fine PM and ozone, exacerbates pre-existing asthma and rhinitis. A causal relationship between new onset of childhood asthma and long-term exposure to outdoor air pollution, especially traffic-related, such as nitrogen dioxide (NO2), fine PM and black carbon, has been reported. Recent data also suggest that long-term exposure to air pollution causally contributes to adult-onset asthma. Air pollution has recently been shown to be a causal factor in the induction, progression and death from asthma of the 9-year-old London girl, Ella Kissi-Debrah. Even short-term exposures to PM2.5, NO2, and ozone may increase asthma mortality risk.
More recently, air pollution, especially truck traffic emissions, has been related to an increase in atopic dermatitis prevalence.
Higher pollen count and allergenicity increase the risk of pollen sensitization and allergy in susceptible individuals. Global warming, drought, extreme rainfall, wind bursts, thunderstorms, air,water, and soil pollution, and land-use changes, profoundly impact plant pollen production, release, dispersion and quality. Increasing concentrations in the atmospheric carbon dioxide (CO2), involved in the photosynthesis process together with increased plant biomass and flowering, result in a higher concentration of airborne pollen. Increasing temperatures lead to an earlier and prolonged pollen season. Air pollutants increase the allergenic load per pollen and change allergen composition.
Geographic and temporal changes in temperature and humidity influence vegetation patterns and plant physiology and modifies pollen distribution. Pollen can travel hundreds of kilometres and, with changing weather patterns and altered species distribution, it has become possible for people to be exposed to new and foreign pollen species from other geographical regions and countries.
|Increased mould spores in the air. Change in climate and the correlated warm and humid conditions affects the quantity, intensity, and frequency of precipitation of moulds, which are well-known risk factors for severe asthma.|
|Thunderstorm-asthma. Sudden and massive allergen release from pollen and moulds after a storm resulted in epidemics of thunderstorm asthma overwhelming the emergency departments in a few hours.|
|Loss of biodiversity. Climate change is a primary driver of biodiversity loss, favoring the development of asthma and allergy through the lack of modulation of the immune system. Conversely, the loss of biodiversity contributes to climate change, for example deforestation increases carbon dioxide, the major “human-produced” greenhouse gas.|