Speaker: ‘We don’t have much time’ to stem impacts of climate change on allergy, asthma
Click Here to Manage Email Alerts
Climate change is having a substantial negative impact on allergies, asthma and other respiratory disorders, according to a presentation given during the European Academy of Allergy and Clinical Immunology Hybrid Congress.
Yet clinicians can play a role in improving care for their patients as well as in changing public policy to combat the effects of climate change, Kari C. Nadeau, MD, PhD, Nadissy professor of medicine and pediatrics at Stanford University, said.
“We as allergy and asthma experts can be a trusted voice in this, and we can be that change,” Nadeau, who also is the director of Stanford’s Sean N. Parker Center for Allergy and Asthma Research, said. “We need to be proactive.”
Some populations are more vulnerable to the dangers of climate change due to demographics, geography and biology as well as sociopolitical or socioeconomic factors. Exposure pathways may include extreme weather events, heat stress, air quality, water quality and quantity, and food security and safety. The quality of the health system where these people live matters as well. These multiple exposures all need to be considered in providing individual care and in creating and implementing policy, Nadeau said.
“Those low- and middle-income countries oftentimes have to suffer the most consequences of climate change and health, and yet those are the countries that are producing the least greenhouse gases,” Nadeau said.
The impacts of climate change on health
Although genetic factors may predispose people to atopic diseases, Nadeau said, environmental factors can trigger or exacerbate those risks. For example, she noted, climate change can impact the immune system of those people born with defective skin barriers.
Already, Nadeau continued, there have been rapid increases in allergic diseases and asthma, now affecting approximately 1 billion people around the world. Also, atopic dermatitis and asthma represent the most prevalent chronic diseases among children, she said, with significant associations with early-life exposures.
“Climate change and global warming are inducing de novo allergies and asthma, especially with air pollution,” she said. “And unchecked global warming will definitely worsen respiratory allergies and more airborne allergens that are associated with asthma attacks.”
Prevalence of total and specific serum IgE has been increasing, with long-term exposure to pollution increasing risks for allergic sensitization, she said. Also, exposure to phthalates has been associated with increased prevalence of AD and allergic rhinitis.
Increases in sIgE to grass and cat allergens associated with exposure to particulate matter 2.5 µm in size has been associated with diesel exhaust pollution. Asthma exacerbation increases with heat stress. Mold proliferation from rain and flooding can increase allergy and asthma.
In 2016, increased thunderstorms in Australia led to asthma-related deaths. Whole pollen grains were swept up into clouds as these storms matured. Moisture in the clouds fragmented the pollen. Dry, cold outflows then carried these fragments to the ground.
“The emergency room was packed with people that unfortunately had pollen allergies,” Nadeau said. “The thunderstorm electrified the pollens, caused more immersion of the pollens into the air, increased the risk of pollen allergies and asthma, and unfortunately led to deaths.”
Meanwhile, increases in pollen counts due to increases in temperatures and carbon dioxide that are already happening in Europe are expected to get worse both there and around the world.
Dust storms due to drought caused by climate change are increasing in Africa and elsewhere, with more asthma attacks particularly among children due to these storms seen in Saudi Arabia.
In 2019, Nadeau said, there were 3.3 million excess deaths due to air pollution. In 2021, the total was 4 million excess deaths.
“And that will likely get worse if we don’t do anything about climate change,” she said.
Increasing wildfires due to global warming and droughts are a key source of air pollution, Nadeau continued. As their smoke circumnavigates the globe, she explained, everyone will be exposed to it, even if they live thousands of miles away.
“We need to think about these contributions as we design our research goals for interventions and implementation,” Nadeau said.
Solving the problem
Solutions can begin in the health care sector, which generates about 4% of the world’s greenhouse gases, Nadeau said.
“We need to think about improving and decreasing pollution in our health care settings as well as decarbonizing health care,” she said.
Nadeau encouraged members of the health care sector to be more proactive in launching projects that reduce the direct impact of environmental factors on the health of people in their communities, beginning with research.
“So many of my patients were coming in and they would say, every year, ‘Oh, my pollen is getting worse. My allergies are getting worse,’” she said. “So, we did research on 17 years’ worth of data collections on pollen, and you can do the same in your own country.”
Nadeau’s research indicated that over those 17 years, the duration of tree pollen allergies increased by 8 weeks, and the duration of mold spore allergies increased by 9 weeks.
“For patients, that’s really meaningful,” she said. “We need to get ahead of that and manage it effectively.”
In Central Valley in California, communities installed air filters on school buses to reduce the amount of exhaust that children were inhaling. This project led to a 30% reduction in asthma.
“These are the data that we can use to help officials change policy,” Nadeau said.
Another project in Finland added forest floor, sod, planters and peat blocks to urban daycare centers that had little to no green space. Within 28 days, children at these centers had increased diversity in their microbiota and enhanced immune regulation.
Clinicians also can work with patients to improve home filtration, provide personal masks and change diets and exercise routines, Nadeau recommended.
Resources are available for clinicians who want to do more, Nadeau said, with information available widely on the internet from organizations such as WHO and EAACI and journals such as The Lancet and Allergy.
The need for action is urgent, she concluded.
“We have a call for emergency action now. We don’t have much time,” Nadeau said. “We need to try to maintain the temperatures in the Paris agreement at 1.5°C. That means we have to limit global temperature increases, restore biodiversity and protect health.”