Isabella Hornick , 2025-05-15 11:49:00
Key takeaways:
- Researchers observed significantly elevated odds for in-hospital mortality with each 1 μg/m3 rise in PM2.5 and PM10.
- The same was true when assessing the likelihood for ICU admission and mechanical ventilation.
Heightened exposure levels to particulate matter before COVID-19 hospitalization raised the odds for poor outcomes in hospitalization, such as mortality, according to results published in Annals of the American Thoracic Society.
“Exposure to PM10 or PM2.5 was associated with increased in-hospital mortality and the need for ICU admission and mechanical ventilation among patients with COVID-19 in South Korea,” Tak Kyu Oh, MD, PhD, associate professor at Seoul National University Bundang Hospital and the College of Medicine at Seoul National University, and colleagues wrote.
In this South Korea-based study, Oh and colleagues assessed 322,289 adults (mean age, 49.9 years; 50.7% men) hospitalized with COVID-19 between October 2020 and December 2021 from two databases to determine if there is a link between PM2.5 and PM10 exposure — found via the AirKOREA database — and in-hospital mortality.
As Healio previously reported, a study published in European Respiratory Journal found that exposure to elevated levels of air pollutants before COVID-19 hospitalization increased length of hospital stay and risk for ICU admission.
Using average monthly PM2.5 and PM10 exposure data, researchers evaluated values spanning up to 1 year prior to COVID-19 hospitalization to the day of COVID-19 confirmation. Notably, the mean PM10 exposure level in this timeframe was higher than the mean PM2.5 level (38.7 μg/m3 vs. 21.2 μg/m3).
In-hospital mortality was reported for 4,633 patients (1.4%), according to the study.
As exposure to PM2.5 went up, so did the odds for in-hospital mortality (adjusted OR = 1.06 per 1 μg/m3 rise; 95% CI, 1.04-1.07). Researchers also observed significantly heightened odds for this outcome with each 1 μg/m3 rise in PM10 (aOR = 1.04; 95% CI, 1.03-1.05).
This study further evaluated the link between PM and ICU admission plus mechanical ventilation. ICU admittance was reported in 7,442 patients (2.3%), whereas mechanical ventilation use was reported in fewer patients (n = 2,600; 0.8%).
Similar to the above findings, as exposure to PM2.5 went up, so did the likelihood for ICU admission and mechanical ventilation (aOR = 1.08 per 1 μg/m3 rise; 95% CI, 1.06-1.1). Researchers also found a significantly elevated likelihood for these outcomes with each 1 μg/m3 rise in PM10 (aOR = 1.05; 95% CI, 1.04-1.07).
When divided into those aged older than 60 years and those aged 60 years or younger, the pattern of higher odds with each rise in PM2.5 and PM10 by 1 μg/m3 held true in both groups during the assessment of in-hospital mortality, as well as ICU admission plus mechanical ventilation.
“Our results suggest that individuals with COVID-19 who reside in areas with high PM levels are a high-risk population that requires more careful monitoring, intensive treatment, and care,” Oh and colleagues wrote.
Perspective
The findings of this study are not surprising but are significant in adding more knowledge regarding the adverse health effects of high levels of particle pollution. Respiratory infections such as COVID-19, influenza and others lead to inflammation in the airways and the lungs. We also know that particulate matter 2.5 μm and smaller can reach the alveolar sacs in the lungs and travel further into the bloodstream. These airborne particles with diameter of 2.5 μm or less can travel deep into the respiratory system and into the bloodstream and have been linked to a wide range of adverse health outcomes mainly related to the immune response that is triggered leading to inflammation. This inflammation along with that related to the infection leads to a likelihood of worse outcomes. Both acute and long-term exposure to air pollution increases susceptibility to and severity of respiratory and cardiovascular diseases by increasing oxidative stress and inflammation.
This study is similar to my experience with patients who live in areas with high levels of particle pollution who experience respiratory infections. Physicians should understand that poor air quality related to elevated levels of PM2.5 can cause inflammation in normal lungs and potentially make a respiratory infection more severe. It can also lead to exacerbations of underlying pulmonary conditions, such as COPD and asthma, and has also been associated with increased incidences of cardiovascular disease. All individuals, especially patients with underlying conditions should be made aware of this and understand how they can monitor the air quality in their locales. This can help them determine if certain days will not be good for extended time outdoors.
Studies such as this provide additional justification for optimally regulating local air pollution and should prompt support for additional research in this area. Individuals should be aware of the air quality where they live, and if symptoms such as cough, shortness of breath or chest pain occur, a discussion with their health care provider is advised.
Albert Rizzo, MD, FACP
Disclosures: Rizzo reports no relevant financial disclosures.
