World Asthma Day: How climate change is increasing cases of asthma

By Lois Zoppi, B.A.May 7 2019Reviewed by Kate Anderton, B.Sc. (Editor)

The effects of climate change are evident. Significant changes in weather patterns, landscapes, and wildlife behaviors have become all too common in recent years. Now, a report by the American Academy of Allergy, Asthma & Immunology (AAAAI) suggests that climate change is affecting those with asthma, too.

wavebreakmedia | Shutterstock

The report, which was published in The Journal of Allergy and Clinical Immunology, explored the link between changing environmental conditions and cases of asthma and allergies. The report was published just a few weeks before, World Asthma Day (7^th May 2019), where the focus is on symptom evaluation, test response, observation and assessment, and proceeding to adjust treatments.

The effects of climate change will be ‘unevenly distributed’

In the present study, the researchers explain that “natural system changes” such as climate and weather change may not be having a significant direct impact on a large number of human populations as of yet, but there are “increasing observations in which the results of climate changes are devastating individual populations.”

When considering pollution created by human industry, the paper also predicts that such devastations will be “unevenly distributed” and affect disadvantaged populations most, citing “those with pre-existing conditions, especially pulmonary and cardiovascular diseases” will be most at risk, among other vulnerable groups such as children or the elderly.

The researchers emphasize that the allergy community should be “knowledgeable” about issues surrounding increased risk from climate change, and “understand the effect on allergy and asthma, and be well-versed in possible means to mitigate adverse health consequences.”

How does the environment affect asthma?

There are a huge number of environmental factors that can worsen a person’s asthma symptoms, and internet searches including climate change, weather change, air pollution, particulates, greenhouse gases, traffic, and insect habitats all show that these issues are at the forefront of many people’s minds.

Pollen count

The duration of pollen seasons has been increasing, resulting in larger amounts of pollen being produced by plants and the earlier onset of pollination seasons. This stretch in pollination seasons has been linked to increasing global temperatures and higher levels of atmospheric CO₂.

Studies show that the ragweed season in certain Canadian cities has increased from 44 days to 71 days in 14 years. Longer pollen seasons have also been observed in Europe with British studies finding the average first flowering dates have advanced by almost five days in a decade.

Italy has also seen increases in pollen season duration and pollen load. In one Italian study, the number of patients becoming sensitized to pollen increased in line with pollination season duration.

Air pollution

The new AAAAI report states that it may be possible that people living in urban areas may be more likely to seek treatment for allergic asthma in the future due to the higher levels of CO₂ in urban areas, as plants that thrive in high-CO₂ environments sometimes produce higher amounts of allergens due to changes in their growth mechanisms.

Weather changes are also closely linked to levels of air pollution. The American Lung Association State of the Air 2017 report did find improvements in air quality in monitoring sites between 2013 to 2015, but the amount of people exposed to dangerous amounts of air pollution is still over 125 million, 38.5 percent of which are living with “unhealthy levels of either ozone or particle pollution.”

Polluted air can cause serious problems for those living with asthma, with particulate matter, especially PM_2.5 being a significant concern. PM_2.5 is a mixture of airborne particles that can come from a number of commonly encountered sources, from vehicles, power plants, and heating systems, to burning of fossil fuels, wildfires, and dust.

There should be continual awareness and research of not only the traditional fossil fuel combustion products, but also other air pollutant sources, such as ultrafine particles and [secondary organic aerosols], and their interplay with climate change and asthma.”

Pollution causes ‘airway hyperreactivity’

The burden of asthma on healthcare facilities can be immense. Air pollution not only increases hospitalization and emergency department visits for those with asthma, along with rising pollen counts, it is also increasing the incidence of asthma.

The report summarises the potent effects of pollution, stating:

Mechanistic studies have demonstrated a role for pollutants in inducing airway inflammation, neutrophil influx, cytokine/chemokine release, production of white blood cells, oxygen free radical production, endotoxin-mediated cellular and tissue responses, stimulation of irritant receptors, and covalent modification of key cellular enzymes. Pollutant exposures can also alter mucus production, damage the airway epithelium […] and trigger airway hyperreactivity.”

Additionally, air pollution can progress asthma cases to chronic obstructive pulmonary disease (COPD), a debilitating set of progressive lung diseases. However, measures are being taken to reduce the effect changing environmental conditions are having on respiratory health.

World leaders are taking action

Fairbanks North Star Borough in Alaska suffers from spikes in air pollution from wildfires and energy sourced from wood and coal. A number of changes were brought into place when the Fairbanks community voiced concerns about their respiratory health, and residents of the borough were offered lower-cost alternatives to oil and firewood for heating and cooking. Alternative energy sources are also being investigated to supply the community with greener energy.

In India, where women are far more likely to report cases of asthma than men due to exposure to pollutants from cooking with gas or solid fuels indoors, the 2016 Ujjwala scheme was created to provide cleaner fuel alternatives to those living under the poverty line to improve respiratory health. The scheme has since been praised by the World Health Organisation.

Climate change is an intensely politicized issue, and governments face significant challenges when developing and running environmental movements because of “differing opinions on economic and political priorities”, but efforts already taken may help to pave the way for officials to take further action and protect people from pollutants, irritants, and allergens.

While the AAAI 2019 report does not highlight one single source as a particular challenge for those with asthma, climate change, air pollution, and asthma severity and incidence are connected.

Community efforts can significantly reduce air pollution, thereby reducing greenhouse gas emission and improving air quality,” and that the allergy and scientific community should “continue to adapt our practices to meet the needs of our patients in the face of ever-changing patterns and presentation of disease that might result from weather and climate changes.”