Air pollution has been linked to a host of poor health outcomes, from respiratory infections to suicide risk. Now, new research in the Wasatch Front of Utah-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 air pollution to 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," says John Pearson, MD, first author on the paper, associate professor of anesthesiology at Stanford Medicine, and research affiliate of anesthesiology at University of Utah Health, who performed the research while at U of U Health.
When air pollution was 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%.
PM2.5 air pollution increases risk of complications
To discover 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 the level of air pollution 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 35ug/m3 is considered unhealthy, the research team found that changes in the level of air pollution above and below this limit also affect risk. Every 10ug/m3 increase in fine particulate air pollution was associated with about 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, also known as PM2.5, due to its systemic effects on human health. "Particles of that size or smaller can get down to the smallest part of the lung," explains Nathan Pace, MD, professor of anesthesiology at U of U Health and a coauthor on the paper. "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.
Pace adds that while this study found an association between air pollution and post-surgical complications, it can't determine that 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 says.
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. Pearson adds that for residents of the Wasatch Front, the flipside of living in a place with high local 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. "It's always a good idea to protect your health during bad air pollution events," Pearson says.
