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Nitrogen dioxide, benzene, and lead were strongly associated with chronic rhinosinusitis (CRS) in a case-control study published in JAMA Otolaryngology–Head & Neck Surgery.

The pollutants, commonly generated by sources such as vehicle exhaust, fuel combustion, and gasoline evaporation, were also linked to distinct inflammatory responses in the sinuses, suggesting that different environmental exposures may contribute to different forms of CRS.

An analysis of sinonasal epithelial specimens found that, after adjustment for demographics, smoking history, steroid use, and comorbidities, higher residential exposure to nitrogen dioxide (NO₂), benzene, and lead was associated with significantly greater odds of CRS. Each standard deviation increase in exposure was linked to a 132% increase in CRS odds for NO₂, a 115% increase for benzene, and a 248% increase for lead. Chromium, 1,3-butadiene, nickel, and zinc were also assessed but did not show an association with CRS.

Although prior research has linked particulate matter exposure to CRS prevalence and severity, little work has examined traffic-related gases and industrial pollutants individually, said Jivianne Lee, MD, professor of rhinology and endoscopic skull base surgery in the Department of Head and Neck Surgery at the University of California, Los Angeles David Geffen School of Medicine. 

The study included 92 adults (48% women; mean age, 50 years) treated at a tertiary referral center in California between 2018 and 2021. Of those, 62 patients with CRS underwent endoscopic sinus surgery, while 30 control participants without CRS underwent skull base surgery. Researchers used geocoded residential addresses and land-use regression models to estimate participants' average exposure to the pollutants during the 5 years before surgery. 

The inflammatory signatures differed by pollutant. NO₂ exposure was associated with elevated levels of IL-4, IL-5, and IL-13, cytokines involved in type 2 inflammation.

Benzene and lead were associated with changes in IL-1RA, IL-6, and IL-8 levels. The researchers suggested that while NO₂ may promote CRS through type 2 immune responses, benzene and lead may contribute through oxidative stress, damage to the sinus lining, and neutrophil-driven inflammation. 

“It was surprising that specific traffic pollutants were associated with CRS and that specific chemicals were associated with a particular pattern of inflammatory cytokine profiles,” said Lee, senior author of the study. 

According to Lee, environmental exposures may eventually help clinicians predict whether a patient is more likely to develop type 2 or non-type 2 CRS. While treatment would still be guided by clinical findings, understanding a patient's exposure history could provide additional insight into disease course and help inform management decisions.

“When we are picking from an array of treatment options for our patients, it would be very helpful to know which ones they’re more likely to respond to,” said Aria Jafari, MD, assistant professor in the Department of Otolaryngology–Head & Neck Surgery at the University of Washington School of Medicine in Seattle, who was not associated with the study. If the CRS is related to their environmental exposures or the region in which they live, he said, it would be an additional piece of information to better guide treatment of these patients.

Jafari said the findings highlight the importance of asking patients about environmental exposures, including where they live and work.

“We can let them know that we’re learning how long-term exposure to traffic exhaust, pollution, and airborne chemicals may chronically inflame the lining of the sinuses over time,” Jafari said. 

Lee said that interventions such as masks and air purifiers may help reduce exposure for some patients.

The study was funded by the US Department of Defense. The sources cited in this article report no relevant disclosures. 

Brittany Vargas is a journalist who covers medicine, mental health, and wellness.