Reposted from U of U Health.
Air pollution has been linked to a host of poor health outcomes, from respiratory infections to suicide risk. Now, new research on Utah's Wasatch Front-which occasionally experiences the worst air quality in the nation-has found an association between high air pollution and risk of post-surgical complications.
The new study, encompassing nearly 50,000 surgery patients, has linked higher levels of particulate air pollution to a higher risk of a combined measure of post-surgical complications that included sepsis, pneumonia, and surgical wound infection.
"When there was an elevation in PM2.5 air pollution in the week before surgery, even for one day, we saw increased risk of major medical complications and infectious complications," said first author John Pearson, a former U assistant professor of anesthesiology who performed the research while at U of U Health. Pearson is now a clinical associate professor at Stanford Medicine and remains U research affiliate.
Fine particulate matter, which can become lodged in respiratory issues and undermine a person's health in a number of ways, is most often associated with the Wasatch Front's wintertime inversions when polluted air is trapped on the valley floor. When PM2.5 levels were higher than the EPA daily exposure limit in the week before surgery, the risk of post-surgical complications increased from 4.8% to 6.2%.
The results are published in Acta Anaesthesiologica Scandinavica. Faculty from the U's College of Social and Behavioral Science contributed to this interdisciplinary research, which was led by the School of Medicine.
PM2.5 air pollution increases the risk of complications
To uncover the relationship between air quality and surgical outcomes, the researchers analyzed post-surgical data from 49,615 non-emergency surgeries in the Wasatch Front. They used a combination of EPA and state-level air quality sensors, as well as satellite data, to estimate PM2.5 levels at each patient's home address for a week before surgery.
The higher the level of air pollution, the greater the increase in risk. While a concentration of fine particulate air pollution of 35 micrograms per cubic meter is considered unhealthy, the research team found that changes in the level of air pollution above and below this limit also affect risk. Every 10 microgram increase in PM2.5 was associated with an 8% increase in the relative risk of post-surgical complications, resulting in an absolute increase in risk of 1.4% when pollution exceeded EPA daily limits.
The researchers were specifically interested in levels of fine particulate air pollution due to its systemic effects on human health. "Particles of that size or smaller can get down to the smallest part of the lung," explained study co-author Nathan Pace, a U professor of anesthesiology. "Some of it will cross into the blood and it can end up anywhere in your body: your brain, your heart, your liver, your kidneys."
This increases overall levels of inflammation, putting stress on the lungs and heart and possibly increasing the risk of infections.
Future directions
The researchers emphasize that this study used a composite measure of complications that combined many different post-surgical outcomes, which means that more research is needed to determine which specific complications are more likely to arise following high air pollution. Research in larger studies, including multiple hospitals, could also help determine which kinds of surgeries are most affected by air quality, which could help health centers time surgeries to minimize risks.
While this study found an association between air pollution and post-surgical complications, it can't determine whether the increased risk is directly caused by air pollution or if there's an unknown third factor that links them both. "A caveat in any observational study is that there might be a relevant factor that affects both the exposure and the outcome," Pace said.
While more research is needed to determine which people and surgeries might benefit from additional risk-reducing interventions, the team says that this work provides even more evidence that better air quality benefits human health. For Wasatch Front residents, the flip side of living in a place with elevated air pollution is that local changes to transit and industry can have a major impact on air quality.
For now, standard precautions-like quality home air filters and avoiding outdoor exercise during wildfire smoke or inversion days-are a healthy choice for everyone, whether or not someone will be getting surgery.
This research was published April 26 in Acta Anaesthesiologica Scandinavica as "Bayesian Analysis of Postoperative Complication Risk Associated With Preoperative Exposure to Fine Particulate Matter: A Single-Center Cohort Study." Co-authors include Long Yin Lee and Neng Wan of the U's School of Environment, Society & Sustainability, Tabitha Benney of the Division of Public Affairs, as well as researchers from the University of Nevada, Reno and Columbia University.
This work was supported by a University of Utah Wilkes Center for Climate Science & Policy seed grant, the National Science Foundation, and the National Institutes of Health, including the National Institute of Environmental Health Sciences and the National Cancer Institute. Content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health, the National Science Foundation or the Wilkes Center.
