The Relationship Between Asthma and Environmental Health

According to the Centers for Disease Control and Prevention, the prevalence of asthma among people in the United States has continued to steadily increase. About 1 in 12, or 25 million, Americans have asthma. The World Health Organization estimated that 262 million people worldwide were affected by asthma in 2019 and that it led to 455,000 deaths. What are the factors influencing increasing asthma rates, and how do they relate to environmental- and climate change-related outcomes? 

Asthma is a disease that is characterized by inflammation of the lungs and airways, also called the bronchi. It is chronic and in many cases requires ongoing medical care throughout a person’s lifetime. Asthma itself causes constriction of the airway, bronchospasms, and inflammation, all of which present a challenge to daily life. Such symptoms are generalized into what are called “asthma attacks,” with other symptoms that may include: 

• Chest pain/tightness 

• Shortness of breath 

• Wheezing coughs and difficulty breathing 

• Wheezing and coughing attacks brought on by triggers like dust, viruses, etc. 

There are a variety of elements that can trigger asthma or asthma attacks in people. These triggers include: 

• Dust, dust mites, and other household pests like mice and cockroaches 

• Molds 

• Pets 

• Smoke from tobacco 

• Air pollution 

• Exercise (in the case of Exercise-Induced Asthma) 

Research supports there are many environmental factors influencing the onset, uptake, and prevalence of asthma. While death rates from asthma are highest in countries of low- and middle-socio-demographic indices (SDI), the prevalence of the disease is greater in countries of high SDI. This means that in a country like the USA, more people have asthma, but fewer die from it. Conversely, in a country like Mali, fewer will be diagnosed with asthma, but those that do have the disease are more likely to die from it. These factors point to an important idea in environmental health science called the hygiene hypothesis. The basis of the hypothesis is that high-SDI countries have developed in such a way that living environments are “too clean” – that is, children are not exposed to as many environmental factors (i.e., germs) that promote the development of immune responses against asthma factors. Newborns in countries with lower SDI will be exposed to these factors at orders of magnitude greater than their counterparts, which explains why prevalence is low in these countries. 

Other studies point to air pollution as a major contributing factor to asthma. Not only is air pollution implicated in exacerbating asthma, but it can also be responsible for the initial onset and development of asthma, leading to more cases of the disease as air pollution increases globally. Urbanization and living in urban areas are also tied to asthma.  

Additionally, there is a possible genetic link to the development of asthma, yet this tie-in has been difficult for researchers to pin down, as they have had difficulty consistently replicating experiments in which specific genetic factors are studied. Still, scientists agree that an element of genetic predisposition exists when it comes to the development of asthma at any stage of life.  

Numerous interventions could help to reduce the incidence of asthma, or at least reduce asthma triggers. The CDC, WHO, and American Lung Association both point to the reduction of smoking as a good way of reducing the risk of developing asthma in smokers and non-smokers alike. Reducing ambient air pollution would also help to reduce cases of asthma. Making an effort to reduce foreign particles of any kind from entering the bronchi is critical in preventing the further development of asthma, especially in youth. 

Finally, it is important to recognize that asthma is not distributed evenly across socioeconomic lines. It is widely studied that those of lower incomes, especially in urban settings like New York City, suffer from asthma mortality at a greater rate than their higher-income counterparts. Therefore, this is as much an issue of environmental justice as it is a public health crisis. 

Understanding how asthma functions in the body, as well as how it affects people at a societal level, is of growing concern as the effects of climate change become more apparent. It will be important to follow how these asthma outcomes further manifest themselves as global climate outcomes continue to change.