Climate Change: Dire Implications for Respiratory Conditions

High exposure to fine particulate matter (PM2.5) from diesel exhaust, airborne dusts, smoke from forest fires, and other sources has been linked to increased mortality and worsening of respiratory disease.1 Studies have found, for instance, that PM2.5 exposure is associated with reduced lung function and increased odds of asthma-related clinical encounters in children.4,5 Recent study findings revealed a specific genetic profile in patients with asthma who are most likely to develop inflammation in response to pollution.6

In addition, a 2017 study reported that increasing levels of PM2.5 increased hospitalization risk and emergency room visits in patients with COPD.7

Extreme Temperatures

The combined effects of heat stress, which disrupts pulmonary perfusion via fluid loss, and elevated pollution levels may increase bronchial inflammation and bronchoconstriction. In a 2016 study, a positive interaction was observed between indoor air temperature and pollution levels and findings showed that individuals with COPD experienced worsening cough, breathlessness, and sputum production in response to increased maximal indoor temperature.8 In earlier research,9 the hospitalization rate of patients living in New York City increased by 7.6% for every 1°C increase in temperature above 29°C.

Low temperatures have also been linked with worse outcomes in respiratory disease, such as increased emergency room visits and hospitalization in patients with COPD.7,10

Pulmonology Advisor interviewed Dr Demain to discuss the implications of climate change in patients with respiratory disease.

Pulmonology Advisor: What does the evidence thus far suggest about the potential effects of climate change on COPD and other respiratory diseases?

Dr Demain: [The data suggest that the following issues related to climate change are relevant to respiratory diseases.]

Allergens: Although not all patients with COPD are atopic, in individuals who are it may be relevant that there is a growing body of evidence that pollen levels will rise in response to increasing CO2 and temperature. Ragweed has been the most studied, revealing not only increased biomass and pollen loads, but also longer seasons.

Mold: Like pollens, an increase in mold growth has been demonstrated in the presence of environments with increased CO2. Damp buildings prone to mold growth are associated with increasing extreme weather events and resultant flooding. Mold exposure not only increases the risk for worsening lung disease because of allergies but is also associated with increasing risk for hypersensitivity syndromes such as allergic bronchopulmonary aspergillosis (ABPA).

Pollution: Pollution is both a cause and an effect of climate change. With rising temperatures, O3 levels will rise. O3 levels, along with PM2.5, have been associated with increased risk for emergency room visits and hospitalizations and decreased lung function.

Wildfires: Rising temperatures and drought increase the risk for wildfires. Particulates from wildfires can result an increase in particulates hundreds of miles away. This results in worsening air quality that has a great impact on respiratory health, especially in individuals with pulmonary disease.

Pulmonology Advisor: What are some of the treatment challenges relevant to this issue?

Dr Demain: More frequent exacerbations and worsening lung disease will continue to stress the medical system. While we are doing a better job of phenotyping specific forms of asthma and therapies are improving and becoming more personalized, some of these therapies are not available to many patients — principally due to cost. Emergency departments are overcrowded and hospitals are functioning at capacity. With the prospect of worsening air quality, increasing pollen levels, longer seasons, and compromised indoor air quality from molds, our healthcare system will likely face increasing challenges.

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Pulmonology Advisor: What are the remaining needs in this area and how might clinicians and others address this issue?

Dr Demain: We need to take a more expansive and coordinated approach to research monitoring of the impact of climate on pollution, air quality, pollen trends, allergic sensitization, and effects on lung disease. As healthcare providers, we can advocate for prevention measures and mitigation and/or become involved in policy debates. Climate and weather patterns will continue to change, and new difficulties will likely emerge that could have an impact on lung disease. Physicians and scientists should be at the table, advocating for and committing to the development of strategies that will protect vulnerable persons at risk for adverse respiratory health outcomes.


  1. Demain JG. Climate change and the impact on respiratory and allergic disease: 2018. Curr Allergy Asthma Rep. 2018;18(4):22.
  2. Fisk WJ, Lei-Gomez Q, Mendall MJ. Meta-analyses of the associations of respiratory health effects with dampness and mold in homes. Indoor Air. 2007;17(4):284-296.
  3. Beck I, Jochner S, Gilles S, et al. High environmental ozone levels lead to enhanced allergenicity of birch pollen. PLoS One. 2013;8(11):e80147.
  4. Khalili R, Bartell SM, Hu X, et al. Early-life exposure to PM2.5 and risk of acute asthma clinical encounters among children in Massachusetts: a case-crossover analysis. Environ Health. 2018;17:20.
  5. Jung KH, Torrone D, Lovinsky-Desir S, et al. Short-term exposure to PM2.5 and vanadium and changes in asthma gene DNA methylation and lung function decrements among urban children. Respir Res. 2017;18(1):63.
  6. National Institutes of Health. Genetics and pollution drive severity of asthma symptoms. Accessed September 19, 2018.
  7. Hasan B. Effect of global climate change-related factors on COPD morbidity. Tanaffos. 2017;16(Suppl 1):S24.
  8. McCormack MC, Belli AJ, Waugh D, et al. Respiratory effects of indoor heat and the interaction with air pollution in chronic obstructive pulmonary disease. Ann Am Thorac Soc. 2016;13(12):2125-2131.
  9. Lin S, Luo M, Walker RJ, Liu X, Hwang SA, Chinery R. Extreme high temperatures and hospital admissions for respiratory and cardiovascular diseases. Epidemiology. 2009;20(5):738-746.
  10. D’Amato M, Molino A, Calabrese G, Cechi L, Annesi-Maesano I, D’Amato G. The impact of cold on the respiratory tract and its consequences to respiratory health. Clin Transl Allergy. 2018;8:20.