Impact of Air Pollution on Lung Health Sparks Call for Physician-Led Action at CHEST 2024

Experts explored the impact of climate change in the chest medicine space through numerous sessions and posters at the CHEST 2024 annual meeting in Boston, Massachusetts, last week.

The topic was first introduced during the keynote address, “The Climate and Health Pandemic,” delivered by Vanessa Kerry, MD, MSc, director of global and climate health policy in the Department of Environmental Health at the Harvard TH Chan School of Public Health.¹ She discussed various effects of climate change, calling on clinicians to recognize these threats and implement sustainable practices to mitigate them.

Kerry emphasized that air pollution is a main driver of climate change.² The 6 most common air pollutants are ground-level ozone (O₃), particulate matter (PM), nitrogen dioxide (NO₂), carbon monoxide (CO), and sulfur dioxide (SO₂)³; these pollutants are regulated by the US Environmental Protection Agency (EPA).

By signing the Paris Agreement in 2015, 195 countries pledged to limit Earth’s temperature increase during this century to 1.5 ° Celsius. However, Kerry noted that temperatures are projected to increase by about 2.8 ° Celsius by the end of the century.³ This increase is largely due to human emissions of greenhouse gases.

Building on Kerry’s call to action, several posters explored the worldwide impact of air pollution on lung function and the role providers play in mitigating these effects.

CHEST 2024 posters demonstrated air pollution's role in lung impairment and disease, highlighting the urgent need for providers to address the escalating impacts of climate change on lung health. | Image Credit: hramovnick - stock.adobe.com

Impact of Air Pollutants on Lung Function

One poster aimed to determine whether the joint effects of annual changes in ambient air pollutant levels are associated with lung function impairment.⁴ Over 5 years, the researchers analyzed the impact of O₃, NO₂, PM_2.5, CO, and SO₂ on lung function impairment. Despite their significant global threat, they noted that the joint effect of ambient air pollutants on lung function impairment has not been proven.

The researchers conducted their study using the Korea National Health and Nutrition Examination Survey (KNHANES) V-VIII database, spanning 2010 to 2018. They included patients aged 40 to 80 years with available data on air pollutants and spirometry (forced expiratory volume in 1 second [FEV₁], forced vital capacity [FVC], and FEV₁/FVC). Also, the researchers considered patients to have lung function impairment if FEV₁ and FVC were less than 80% and if FEV₁/FVC was less than 70%.

Given the varied scales and data distributions of air pollutants, they assessed the effects of changes in each pollutant on continuous lung function parameters and impairments in quartile increments. The joint effect of air pollutants was analyzed, along with the individual impact weights of each air pollutant.

Of the 29,115 patients in the KHANES V-VIII database, 8660 exhibited lung function impairment. The researchers determined that the joint effect per quartile increment in air pollutants was associated with increased risks of FEV₁/FVC (OR, 1.06; 95% CI, 1.01-1.11) and FEV₁ (OR, 1.05; 95% CI, 1.02-1.08) impairments.

Also, NO₂ contributed most to FEV₁ impairment, followed by CO (15%), PM_2.5 (11%), and O₃ (5%). As for FEV1/FVC impairment, CO contributed the most (53%), followed by NO₂ (24%), O₃ (12%), and SO₂ (11%).

“The findings contribute substantially to understanding the real-world impact of air pollution and provide a foundation for further research and evidence-based policy decisions,” the authors concluded.

Effect of Long-Term Exposure to Air Pollutants on COPD Risk

Other posters examined the impact of air pollutants on specific disease states, like chronic obstructive pulmonary disease (COPD). One poster aimed to determine the effect of combined long-term exposure to various air pollutants on COPD onset.⁵

The researchers used linked data from the KNHANES spanning 2010 to 2017, along with annual air pollutant data from the Ministry of Environment based on administrative units. To evaluate long-term exposures, they analyzed the 5-year average concentrations of CO, NO₂, O₃, SO2, PM_2.5 and PM₁₀ at residences before the survey year. Additionally, they implemented a quantile g-computation (qgcomp) and Bayesian kernel machine regression (BKMR) to estimate the joint effects of air pollutants on COPD.

Of the 21,804 survey participants, 3515 had COPD. Compared to the non-COPD group, the mean (SD) FEV₁ percentage was significantly lower among the COPD group (78.2 [15.7] vs 96.2 [10.3]; P < .001).

Based on the qgcomp analysis, O₃ contributed the most to COPD onset (36%), followed by NO₂ (33%), PM_2.5 (24%), CO (6%), and SO₂ (1%). Conversely, PM₁₀ exhibited a negative association with COPD onset. Overall, a 1 quartile increase in all air pollutants was associated with increased COPD odds (OR, 1.23; 95% CI, 1.12-1.35).

Similarly, the BKMR analysis demonstrated a positive association between the overall effect of air pollutants and COPD odds. More specifically, a significant increase in COPD odds was observed as air pollutant concentrations rose from the 25th to the 75th percentile.

Lastly, the researchers examined the posterior inclusion probabilities (PIPs) as indicators of the relative importance of each air pollutant. The PIPs for O₃ and NO₂ exceeded the 0.5 threshold, indicating their relative importance in the association between air pollutant mixture exposure and COPD onset.

“It is suggested that in order to reduce the incidence of COPD, it is necessary not only to limit individual pollutants but also to regulate the mixture of air pollutants,” the authors concluded.

The Role of the Provider in Mitigating Air Pollution Effects

These posters demonstrated the effects of long-term air pollutant exposure on respiratory health; it impairs lung function and increases COPD risk. Consequently, they indicate to providers that protection against air pollutants is needed to mitigate adverse respiratory outcomes among patients.

One poster aimed to improve the knowledge of training physicians on the impact of air pollution exposure and ways to counsel vulnerable patient populations on prevention techniques.⁶

The researchers analyzed 53 physicians currently in medical residency in the Northeast region of the US. They took a 32-question pretest survey created using a compilation of online literature and environmental resources. It addressed various topics, including participants’ knowledge of air pollution sources, preventive measures for limiting exposure, and attitudes toward including air pollution in practice and training.

After the pretest, participants were given a 15-minute resident-led educational presentation. Then, they were asked to fill out the same questionnaire as a posttest assessment.

Of the 53 participants who completed the pretest questionnaire, 27 completed the posttest. Of those who completed both questionnaires, about 68% reported receiving no lectures on the effects of air pollution on human health during medical training. Conversely, 28% reported receiving 1 lecture and 4% received 3 or more lectures.

Sixty-seven percent of participants indicated they care for those with chronic or acute respiratory diseases daily. Before the presentation, 26% reported a strong association between air pollution levels and disease severity; this increased to 59% after the presentation. Lastly, although 56% of participants correctly identified methods to limit general air pollution exposure on the pretest, 89% identified them correctly post presentation.

On average, participants scored 52.8% on the pretest and 89.2% on the posttest. Therefore, there was a 36 percentage point increase in scores after education intervention (P < .00018).

“Our study suggests that continuing education about air pollution for training physicians can assist them in confidently counseling vulnerable patient populations,” the authors concluded.

References

1. McCormick B. Air pollution increases IPF exacerbations, but role in disease progression remains uncertain. AJMC^®. October 6, 2024. Accessed October 14, 2024. https://www.ajmc.com/view/air-pollution-increases-ipf-exacerbations-but-role-in-disease-progression-remains-uncertain

2. Keynote speaker: pulmonary, critical care clinicians play vital role in response to climate crisis. CHEST Daily News. October 7, 2024. Accessed October 14, 2024. https://chestdailynews.chestnet.org/keynote-speaker-pulmonary-critical-care-clinicians-play-vital-role-in-response-to-climate-crisis/

3. Environments and contaminants – criteria air pollutants. EPA. 2023. Accessed October 14, 2024. https://www.epa.gov/americaschildrenenvironment/environments-and-contaminants-criteria-air-pollutants#:~:text=The%20six%20most%20common%20air,sulfur%20dioxide%20(SO2).

4. Gu KM, Lee JK J, Heo E, Lee HW. Joint effects of air pollutant changes on lung function. Poster presented at: CHEST Annual Meeting 2024; October 6-9, 2024; Boston, MA. doi:10.1016/j.chest.2024.06.2968

5. Baek MS, Kim C, Park B. The effect of long-term exposure to a mixture of air pollutants on chronic obstructive pulmonary disease. Poster presented at: CHEST Annual Meeting 2024; October 6-9, 2024; Boston, MA. doi:10.1016/j.chest.2024.06.2810

6. Barua S, Romano M, Seibert M, Saffran G, Bender MT. Air pollution and the role of the provider. Poster presented at: CHEST Annual Meeting 2024; October 6-9, 2024; Boston, MA. doi:10.1016/j.chest.2024.06.2334