The Impact of Climate Change on Respiratory Care: A Scoping Review

Abstract

Background

Fossil fuel combustion and climate change are endangering respiratory health. As these threats increase, healthcare delivery systems must adapt and build resilience. In this scoping review, we aim to assess the current landscape of respiratory care impacts from climate change, identifying priorities for future study.

Methods

We performed a scoping review of scientific and gray literature, and selected institutional websites, to understand the impacts of climate change on respiratory healthcare.

Results

Medline, Embase, Scopus, Cochrane Library, Lens.org, and Google Scholar were searched from database inception through 28 July 2023. The initial search yielded 1207 unique articles. Of the 67 articles identified as relevant to the impacts of climate change on respiratory care, 50 (74.6%) had been published between 2020 and 2023. The most studied climate change and severe weather exposures were extreme heat (n = 31, 46.3%), particulate matter not from wildfires (n = 22, 32.8%), and wildfires (n = 19, 28.4%). Respiratory-related hospital admissions (n = 33, 49.3%) and emergency department visits (n = 24, 35.8%) were the most common study outcomes. Few studies identified potential impacts on telehealth services, facility energy distribution, and pharmaceutical supplies.

Discussion

Climate change is projected to increase respiratory-related emergency department visits and hospital admissions. Limited research is available on current and projected economic costs, infrastructure effects, and supply chain impacts. While climate change and extreme weather are increasing strain on respiratory care systems, additional work is needed to develop evidence-based strategies for climate adaptation.

1. Introduction

Climate change has wide-ranging, deleterious effects on respiratory health. The combustion of fossil fuels results in direct health impacts through the release of fine particulate matter and other respiratory disease-promoting factors [1]. Fossil fuel pollution exerts further stress on the human respiratory system by driving anthropogenic climate change. Extreme weather events, made more common in a warming world, including prolonged and intense heat waves [2], expansive droughts [3], profuse wildfires [4], and earlier and more intense allergy seasons [5], endanger the lung health of adults and children. These threats are of particular concern for populations already shown to be most vulnerable to the effects of climate change, including children [6], pregnant people [6], the elderly [7], patients with pre-existing lung disease [8], and those who have experienced the consequences of historic economic and/or systemic injustices [9].

While the public health impacts of air pollution (e.g., fine particulate matter) and extreme climate change-exacerbated events (e.g., wildfires) on respiratory health and mortality have been extensively studied and reviewed [1,10–12], the effects of climate change on respiratory healthcare delivery have not. To adequately respond to the climate crisis, patients, providers, and health systems must develop evidence-based solutions to reduce respiratory-related morbidity and mortality. Healthcare systems frequently provide the last line of defense for climate-related health emergencies, offering refuge to patients suffering the acute effects of poor air quality, severe heat, flooding, and other extreme weather events. It is therefore important to understand how care providers have experienced climate change, how they are adapting, and what innovations are worthy of further study and investment to protect respiratory health in a changing world.

2. Methods

2.1. Aims and research questions

This scoping review aims to understand how respiratory care systems worldwide experience the effects of climate change and extreme weather by answering the following research questions:

• What are the key respiratory care delivery outcomes related to climate change, and how are these impacts measured?

• What evidence exists to improve climate adaptation and infrastructure “hardening” (i.e., building resilience to extreme weather and other natural disasters)?

• Where are the greatest gaps in the literature, and which populations or geographical locations demand urgent attention and future investigation?

2.2. Study protocol and search strategy

An experienced health sciences librarian (C.S.) generated search terms based on six sentinel articles [13–18]. Reference tracking was performed in Scopus. The original search strategies were developed in PubMed and translated as appropriate to the other databases using the Systematic Review Accelerator Polyglot tool [19]:

((lung neoplasms[mh] OR “lung cancer*”[tw]) OR “pulmonary disease, chronic obstructive”[mh] OR “pulmonary disease*”[tw] OR “respiratory disease*”[tw] OR “asthma”[tw]) AND (“climate change”[mh] OR “climate change”[tw] OR extreme weather[mh] OR “extreme weather”[tw] OR “global warming”[tw]) AND (health care[tw] OR “health care”[tw] OR delivery of healthcare[mh] OR “Patient Care Management”[mh] OR mitigation[tw] OR attitude to health[mh] OR awareness[mh] OR awareness[tw] OR education[mh] OR education[tw] OR “percep*”[tw] OR polic*[tw] OR knowledg*[tw])

A systematic search of MEDLINE (PubMed), EMBASE (Embase.com), Scopus (Elsevier), and Cochrane Library - CENTRAL, was conducted from the time of inception of each database to identify articles addressing the impact of climate change on respiratory care. Gray literature was identified by searching Google Scholar @ UM (the first 200 results were selected and screened), Lens.org, and selected institutional websites (US Centers for Disease Control and Prevention, World Health Organization (WHO), and The Lancet) were searched manually [20]. Findings are reported according to the PRISMA Extension for Scoping Reviews (PRISMA-ScR): Checklist and Explanation [21].

All searches were completed by 23 August 2023. Citations were imported into EndNote 21 (Thomson Reuters, New York, NY) for deduplication (with the exception of records from Lens, which were directly imported into Covidence), then exported into Covidence [22] for further deduplication and analysis.

For full details of the search strategy, please see the Supplementary Appendix A.1.

2.3. Eligibility criteria

Peer-reviewed quantitative, qualitative, and mixed-methods studies, as well as reviews published from database inception through 28 July 2023 were considered for inclusion. Articles in English, French, and Russian were eligible for inclusion (languages selected based upon the native fluency of the author group). The included articles were required to address the effects of climate change or extreme weather on respiratory care. Respiratory care was broadly defined to include (1) hospital care, (2) emergency department (ED), or (3) ambulatory clinic care for respiratory illness; (4) respiratory medication procurement or supply chain delivery of durable medical equipment; (5) telehealth; and (6) any other aspect of healthcare delivery that could be viewed as relevant to patients with respiratory disease (e.g., pulmonary function testing, pulmonary rehabilitation, insurance coverage, cost, and quality and safety measures) [23].

Articles were excluded that did not investigate a climate change-driven event or extreme weather exposure or if there were no pertinent respiratory care outcomes. Commentaries, editorials, case reports, and opinion pieces were also excluded.

2.4. Data extraction and analysis

A single reviewer (A.S.R.) completed a title and abstract review to identify relevant literature. Two authors (J.R.L. and A.S.R.) then completed a full-text review. When there was a discrepancy in adjudication, a conversation was initiated between authors to determine eligibility, and in every instance, consensus was achieved for final inclusion. Single-reviewer data extraction was then completed by two authors (J.R.L. and A.N.K.) with oversight provided by the senior author (A.S.R.). The author group sorted articles to identify major themes according to descriptors and findings to generate a thematic synthesis [24–26].

3. Results

An initial search yielded 1271 articles. Of these, 64 duplicates were removed. After title and abstract screening, 720 articles were deemed irrelevant. The remaining 487 full-text studies were assessed for eligibility, of which 420 studies were excluded. The most common reason for exclusion was that the outcomes measured did not relate to respiratory care (n = 343). A total of 67 studies were included for data extraction (Supplementary Table A.1.), of which 50 studies (74.6%) were published between 2020 and 2023. The article selection process is shown in the PRISMA flow diagram (Figure 1) as well as a summary of study findings (Table 1).

Figure 1: Flow Diagram of Study Selection.

PRISMA diagram demonstrates the selection of studies included in the scoping review.

Table 1:

Summary of Included Studies

	N (%) of studies
Year of publication
Prior to 2000	0 (0%)
2000–2009	3 (4.5%)
2010–2019	14 (20.9%)
2020–2023	50 (74.6%)
WHO Region
African	2 (3.0%)
Americas	29 (43.3%)
South-East Asia	4 (6.0%)
European	8 (11.9%)
Eastern Mediterranean	0 (0%)
Western Pacific	12 (17.9%)
Multiple Regions	12 (17.9%)
Primary Exposure (studies may be counted more than once if there were multiple primary exposures)
Temperature - heat	31 (46.3%)
Temperature - cold	8 (11.9%)
Wildfires	19 (28.4%)
Hurricanes	8 (11.9%)
Thunderstorms	4 (6.0%)
Temperature variability	7 (10.4%)
Particulate matter (not primarily from wildfires)	22 (32.8%)
Other	15 (22.4%)
Primary outcome (studies may be counted more than once if there were multiple primary outcomes)
Hospital Admission	33 (49.3%)
Emergency Department Visit	24 (35.8%)
Other Healthcare Utilization*	20 (29.9%)
Health Outcomes†	13 (19.4%)
Other‡	5 (7.5%)

^*Other healthcare utilization includes ambulance dispatches, costs, outpatient visits, and prescriptions.

^†Health outcomes include mortality and other measures of illness severity.

^‡Other includes social disparities of health, clinical practice recommendations, and healthcare system recommendations.

3.1. Respiratory healthcare utilization

Climate change-related respiratory healthcare utilization was measured principally in terms of acute care (ED visits and hospital admissions), with 70.1% of the reviewed articles adopting one or both as primary endpoints (Figure 2).

Figure 2: Primary Outcomes of Included Studies.

Hospital admissions and emergency department visits constituted the largest share of primary study outcomes. N.B. Studies may be counted more than once if there were multiple primary outcomes. *Other healthcare utilization includes ambulance dispatches, costs, outpatient visits, and prescriptions. †Health outcomes include mortality and other measures of illness severity. ‡Other includes social disparities of health, clinical practice recommendations, and healthcare system recommendations.

Although not all studies met thresholds for statistical significance, studies conducted in different populations and geographies generally found that extreme heat was associated with higher odds of respiratory-related acute care visits [27–32]. In a case-crossover study of chronic obstructive pulmonary disease (COPD) hospitalizations in England from 2007 to 2018, every 1°C rise in temperature above 23.2°C was associated with a 1.47% increase in hospitalization (95% Credible Interval 1.19–1.73) [33]. Similarly, in the US state of Alaska, a heat index threshold above 21.1°C (70°F) increased the odds of ED utilization, while ED visits for both asthma and pneumonia were highest the day after a heat event [34].

The effects of wildfire smoke and air pollution similarly showed consistent trends toward increased acute care utilization for respiratory causes. A 2016 review article by Reid et al. on the health impacts of wildfire smoke identified a number of prior studies showing increases in ED visits and hospitalizations [35]. More recent research bolstered these findings, including an Australian study of that country’s 2019–20 bushfire season that demonstrated a 6% (95% empirical Confidence Interval [CI] 1.9–10.3) increase in ED visits for respiratory diseases in regions of the country with lower markers of socioeconomic status and high fire density [36].

Among the studies examining emergency medical service (i.e., ambulance) utilization, there was evidence of increased utilization during extreme cold and heat. Sangkharat et al. found that extreme cold temperatures (less than 0°C) in London, UK were associated with more ambulance dispatches for asthma, dyspnea, and respiratory infections, with the relative risk (RR) ranging from 1.39 (95%CI 1.16–1.70) for asthma to 2.08 (95%CI 1.67–2.57) for respiratory infections. Meanwhile, extreme heat (greater than 22.8°C) was associated with increased ambulance calls for exacerbations of COPD (RR = 1.27, 95%CI 1.18–1.36) [37]. Another study demonstrated that immediate exposure (within one hour) to a 10 μg/m³ increase in fine particulate matter (PM_2.5) during wildfire season was associated with more frequent ambulance dispatches for respiratory conditions [38]. A more recent systematic review and meta-analysis of ambulance dispatches showed that for every 5°C increase in mean temperature, the use of ambulance services increased for all-cause diagnoses and for cardiovascular disease, but not for respiratory-related diagnoses [39]. However, the authors identified potential biases, including possible misclassification of respiratory disease.

Only one study investigated the impact of heat on primary care visits for respiratory-related diseases. Vashishtha et al. analyzed outpatient visits for heat-related illnesses, including respiratory disease, during six heat wave events in southern California, US between 2012 and 2016 and found no significant relationship between heat and ambulatory care utilization as measured by assignment of a heat-related diagnosis code (adjusted odds ratio [OR] 1.35, 95%CI 0.86–1.36, p = 0.51) [40].

3.2. Respiratory disease-related healthcare costs

Future projections of healthcare costs attributable to climate change were limited, although several analyses suggested the likelihood of increased healthcare costs related to respiratory illness-related acute care in a warming climate. In a 2012 study, Lin et al. estimated that heat-related admissions for respiratory disease in the US state of New York would likely rise two to six fold by 2080–2090 compared to a 1991–2004 baseline [28]. In a separate study, costs of respiratory-related care were similarly projected to rise in the western United States owing to increasingly severe wildfire events [41]. A simulation study predicted that climate change-driven temperature increases in Australia could result in a 140% increase in respiratory disease-related hospitalization costs by the 2050s [42].

3.3. Effects on select and vulnerable populations and geographic distribution

Of the 67 studies reviewed, 53 examined the effects of extreme weather on specific demographic groups. A series of studies showed that elderly populations were more affected by adverse weather events, as supported by increased ED visits [43], hospitalizations during times of high temperature variability [44], and prolonged heat wave duration [27]. In a nationwide time-series study of wildfire smoke-related hospital admissions from 2000–15 in Brazil, Ye at al. demonstrated that the very young and the old were at highest risk for all-cause hospital admission (RR 4.88, 95%CI 4.47–5.28 for ages ≤ 4, RR 3.70, 95%CI 3.2–4.2 for ages ≥ 80 vs. RR 0.83, 95%CI 0.44–1.23 for ages 30–39) [45]. The same study showed that for every 10 μg/m³ increase in wildfire-related PM_2.5, there was a 5% (95%CI 4.73–5.44) increase in respiratory-related hospital admissions [45]. Other isolated effects of climate change appeared to occur independently of age. Among those seeking ED care for asthma on thunderstorm days with heavy precipitation and cool temperatures in Louisiana, for instance, the risk of exacerbation was higher among children compared to adults (RR 1.27, 95%CI 1.06–1.53); the association with age did not carry over to non-thunderstorm days with heavy daily precipitation [46].

Among seven studies that focused on children [6,32,47–51], researchers identified those under the age of 18, and especially those under the age of 5 [51], to be at increased risk for climate-related respiratory exacerbations. The varied climatological exposures studied included heavy precipitation [49]; drought [48]; wildfires [45,51,52]; temperature, humidity, and air pollution [32,50]; and aeroallergens [47]. Extremes of precipitation presented challenges to children’s respiratory health: heavy precipitation was associated with 11% higher odds (95%CI 1.02–1.21) of asthma exacerbation resulting in outpatient and inpatient acute care compared to non-precipitation days in the US [49]. In the Brazilian Amazon, a 2010 drought was linked to wide-ranging increases in pediatric hospitalizations (1.2–267%) in a large proportion of affected municipalities compared to the region’s 10-year mean [48]. The risk of hospitalization was in part believed to result from aerosolized particulate matter generated from a variety of human-exacerbated changes, including land use conversion [48].

Ten articles noted differences in healthcare utilization based on race, ethnicity, and underlying disabilities among communities known to suffer disparate pulmonary health outcomes [9]. Some studies examined the disparate effects of specific natural disasters on vulnerable populations. For example, a survey of non-Hispanic black residents of Houston, Texas found higher odds of post-traumatic stress following Hurricane Harvey (OR 5.03, 95%CI 1.90–13.10) and a non-significant trend toward decreased healthcare access (OR 1.57, 95%CI 0.79–3.12); residents with a disability were significantly more likely to face challenges accessing healthcare than those who did not have a disability (OR 3.19, 95%CI 1.37–7.45) [53]. Severe wildfires in the Canadian subarctic during the summer of 2014 also disproportionately affected the healthcare utilization of indigenous peoples [54], while infrastructure deficiencies and debt linked to longtime political marginalization likely contributed to the disastrous aftermath of Hurricane Maria in Puerto Rico [55].

The geographic representation of authors and study locations was not representative of the global population. While most studies focused on North America, Europe, China, and southeast Asia, there was a paucity of studies from South American, Caribbean, African, and Asian countries. Of the five articles from South America, four originated from Brazil and one from Chile. There were only two papers examining the Caribbean region and two from the African continent; among the latter group, both were specific to the country of South Africa. In addition, review papers included in our analysis were often limited to an examination of English-speaking countries, excluding large swaths of the globe most vulnerable to the effects of climate change [56].

3.4. The role of telehealth

The scoping review found very few studies examining the relationship between climate-related exposures and telehealth services and accessibility, or the influence of extreme weather on access to high-speed internet and electricity for respiratory care. Only one included paper evaluated climate-related exposures and telemedicine: In a trial of 62 patients in Germany with COPD experiencing “heat stress days” (i.e., days when the maximal temperature was greater than 25°C), investigators randomized patients to tele-monitoring (including COPD clinical assessment, daily lung function, and weekly 6-minute walk testing) versus usual care. The trial showed that over the 9-month study period, patients undergoing tele-monitoring had fewer COPD exacerbations (7 vs. 22, p = 0.01), shorter cumulative hospital stays (34 vs. 97 days), and fewer specialist consultations (24 vs. 42, p = 0.04) as compared to controls [57].

3.5. Power outages and adverse respiratory health outcomes

It is known that climate change and adverse weather events affect critical infrastructure needed for healthcare delivery. Power grids supplying electricity essential to hospital operations are at elevated risk during wildfires, droughts, and other extreme weather events [58]. Although one study included in the review showed that power outages in New York City were associated with higher rates of COPD-related hospital admission (RR 1.61, 95%CI 1.05–2.48 at day two following power outage) [59], there was scant additional evidence exploring the effects of prior or projected future extreme events on respiratory care.

3.6. Effects on respiratory medication supply chains

While two studies commented on the need for healthcare providers to ensure proper respiratory home medication supply in preparation for extreme heat events and/or poor air quality days [60,61], we did not uncover any primary research of climate change effects on respiratory medication supply or drug distribution. Many articles highlighted increased rescue medication utilization during extreme weather events, including a positive association between exposure to wildfire-related fine particulate matter and salbutamol dispensations (RR 1.06 95%CI 1.04–1.07 for every 10 μg/m³ increase in wildfire-related PM_2.5) [62]. In addition, one included scoping review underscored the risks of extreme weather to medication access following disasters such as hurricanes [63].

3.7. The practice of respiratory medicine in a changing climate

Four publications examined the effects of climate change on the practice of respiratory medicine, including the importance of educating at-risk populations. George et al. explored how nurses can play a role in mitigating climate change by focusing research efforts on the effects of climate change while educating patients on planetary health [18]. Further, Balakrishnan et al. summarized the climate effects on respiratory healthcare with the aim of building climate literacy among pulmonary providers [13].

3.8. Adaptation for the future

Very limited research on respiratory care system adaptation was identified. One exception was a pilot study of training on personal protective equipment use (e.g., N95 respirators) in the aftermath of Hurricane Harvey in 2017 [64]. Researchers noted a high incidence of respiratory symptoms in the weeks following the flooding disaster, as well as high respirator utilization (98%) [64]. Yet similar studies addressing health system resilience were generally lacking, with the included reviews consistently underscoring a lack of data on climate-disaster preparedness [60].

4. Discussion

This scoping review of respiratory healthcare impacts from climate change and extreme weather shows that patients, and especially vulnerable populations such as children and the elderly, are experiencing adverse respiratory health outcomes. These negative effects risk stressing under-resourced care delivery systems. Respiratory healthcare utilization, as measured by ED visits and hospitalizations, has increased. These impacts have been driven primarily by extreme weather events, including severe heat waves, wildfires, hurricanes, drought—and to a lesser extent extreme cold and floods.

Nonetheless, our review highlights the vast knowledge gaps pertaining to respiratory disease management and health system adaptation in a changing climate. Most of the literature identified in this field has focused narrowly on acute, hospital-based care for climate-related respiratory health, with relatively little attention paid to the effects of climate change on primary care for respiratory illness or pre-hospital care. In addition, while previous work has shown an increased need for acute bronchodilator medication dispensation during wildfire smoke events [62,65] and increased demand for all respiratory medications during short-term exposure to extreme heat or cold [66], we did not identify any literature examining the effects of climate change on medication distribution or pharmacy operations, which are basic necessities of respiratory disease management.

Another key finding of this review was the scarcity of published research originating from large swaths of the Global South that are expected to confront the worst effects of climate change [56]. Areas of the developing world that have contributed the least to climate effects now also face increasingly severe weather and climate effects without the research or healthcare resources necessary to bolster healthcare systems [67]. This is of particular concern for respiratory disease management, as, worldwide, the WHO estimates that outdoor air pollution results in over four million excess deaths per year [68].

Despite the large content areas in need of scientific exploration, the increase in the number of reports generated on the topics of respiratory health and climate change in recent years has been notable. A growing number of physician viewpoints and policy perspectives, although excluded from the present scoping review, highlight the increased awareness of climate change among respiratory care providers [69,70]. Still, scientific study of respiratory disease outcomes, economic costs, and innovations in climate resilience and adaptation are urgently needed to bolster healthcare systems as climate change increasingly threatens care delivery.

4.1. Strengths and weaknesses

Strengths of our approach included the broad literature search comprising any aspect of respiratory healthcare that could be affected by climate change (performed using six databases, including a gray literature search). Over 1,000 papers were considered in multiple languages, and our multi-disciplinary review team included an experienced health sciences librarian.

The targeted approach of our article inclusion process, focusing on climate change-related exposures (as opposed to weather impacts alone) and healthcare delivery outcomes, may have led to the exclusion of a substantial body of literature connecting respiratory care to climate change. This was evident upon further examination of review papers, including those by Reid et al. [35], showing that a number of cited articles on climate change-related respiratory health outcomes had been omitted from the present review [71]. As the primary focus of the article was to identify novel aspects of respiratory care delivery rather than to re-examine known epidemiological associations, we felt that these gaps did not substantially deter from the cumulative findings of the paper. In addition, the study may have been subject to misclassification bias as respiratory-related outcomes frequently overlapped with cardiac or other organ-system outcomes. Future reviews may consider adopting knowledge maps to minimize the impact of such bias. Consistent with previously described scoping review methodology [26], we did not perform a quality assessment of the included articles. The inclusion of lower-quality studies may limit the strength of our conclusions.

4.2. Future directions

The scoping review has identified several key areas for future research to better elucidate the effects of climate change on respiratory care:

1. Understudied populations: Africa, South America, large portions of Asia, and the Caribbean stand out as vastly under-researched geographies. Many healthcare systems in these areas of the Global South are likely to experience the worst impacts of climate change, yet they remain understudied and thus at risk of underrepresentation in future policymaking.

2. Going beyond acute care: Studies to date have largely adopted ED visits and hospitalizations as proxies for healthcare utilization from climate change effects. Primary and specialty respiratory care utilization, emergency medical service calls, supply chain impacts, effects on long-term care and pulmonary rehabilitation, respiratory pharmaceutical availability, and studies of economic impacts would be useful to inform policies related to climate change preparedness and the provision of respiratory care.

3. A focus on solutions: Studies have consistently demonstrated that fossil fuel pollution and climate change have exacerbated respiratory health, yet there remains relatively little research focus on solutions. Telehealth is one such technology that may provide low-carbon, high-quality healthcare [72], but how best to integrate this tool in the areas most affected by climate change or extreme weather remains unexplored. Insurers, architects, urban planners, health system engineers, sustainability experts, regulators, and other related stakeholders must play a role in constructing a resilient healthcare system.

4.3. Currently available resources

There are several existing resources and tools to help respiratory care providers and investigators generate new research questions and healthcare-based interventions to improve climate resilience. The US government has a publicly available online “toolkit” with suggestions on the provision of healthcare during extreme weather events [73]; prominent journals have offered generalized findings and recommendations on how to improve healthcare delivery infrastructure in the face of climate change [74,75]; the WHO has created a report on the current status of healthcare systems [76]; and reports are available to supplement understanding of how allied health professionals can work together to create systemic change [77].

5. Conclusions

Our scoping review of climate change-related impacts on respiratory healthcare delivery has identified important future research opportunities. Ambulatory care, medication availability, telehealth, and supply chain distribution for respiratory care are under-researched. More work is needed to address the lack of representation in geographies most at risk of climate impacts and to develop systemic health interventions to ensure that patients in need of respiratory care can receive it.