What Exactly Are You Inhaling When You Wear a Face Mask?

Face masks release chemical compounds, and new research shows surgical masks and FFP2s are the worst offenders.

wavebreakmedia/Shutterstock

Disposable face masks, such as those health officials encouraged (or in some cases, mandated) the public to wear during the COVID-19 pandemic, are made of synthetic fibers and may contain chemical compounds. Many people have questioned the wisdom of wearing masks made of synthetic fibers for long periods, asking whether inhaling the chemical compounds masks release could lead to health problems.

Masks may release up to 5,390 microplastic particles in a 24-hour period and surgical masks in particular may release approximately 3,152 microfibers in less than one hour, according to a review in the journal Ecotoxicology and Environmental Safety in April.

To perform this review, German and Swiss researchers examined 24 studies evaluating 631 surgical, cloth, and N95 masks to determine their composition and the compounds they released. Sixty-three percent of the masks showed “alarming results,” the researchers wrote, releasing high amounts of micro- and nanoplastics.

The researchers found that many substances in the masks—among them volatile organic compounds (VOCs), xylene, acrolein, per- and polyfluoroalkyl substances (PFAS), phthalates, lead, cadmium, copper, and titanium dioxide (TiO₂)—exceeded the established safety limits for humans.

In a 2022 article published in the journal Nature, a group of researchers determined that 12 types of masks all “exceeded the acceptable exposure level to TiO2 by inhalation,” and they called for regulatory standards for the use of TiO2, a potential human carcinogen.

The Latest Research

The latest study of this type, “Comprehensive Risk Assessment of the Inhalation of Plasticizers From the Use of Face Masks,” which recently appeared in the journal Environment International, tested four types of masks for the presence of 31 types of plasticizers. It also investigated to what extent these compounds and others were released (and thus inhaled) during simulated mask use.

While “overall plasticizer concentration was similar in all four face mask types,” the researchers report, they found surgical masks and FFP2s (widely used in Europe) had high plasticizer release rates of around 4 percent (3.9 percent and 4.8 percent, respectively).

“Face masks are predominantly composed of synthetic materials,” most commonly polypropylene, polystyrene, polyethylene terephthalate, and polyester, the researchers wrote. The researchers were part of the Environmental and Water Chemistry for Human Health (ONHEALTH) group within the Institute of Environmental Assessment and Water Research in Barcelona, Spain.

Manufacturers also incorporate additives such as phthalates and organophosphate esters (OPEs) into masks as plasticizers “to increase softness and flexibility, or as a flame retardant,” the researchers stated. Other chemical compounds found in masks include heavy metals, PFAS, and VOCs.

In the ONHEALTH study, the average plasticizer concentrations found in different mask types were: 7.27 micrograms in surgical masks, 8.61 micrograms in reusable masks, 11.0 micrograms in KN-95 masks, and 13.9 micrograms in FFP2 masks.

Inhalation Simulation Tests

To investigate the amounts of plasticizers the masks released, the researchers conducted inhalation experiments on paper-mâché dummy heads to replicate typical use in humans. The findings showed that higher temperatures mimicking human breathing caused higher release of plastic additives. “The high-temperature condition [in the experiment] presents the worst-case scenario for the release of plastic additives,” the researchers wrote.

The amounts of compounds the masks released varied widely, ranging from 0.1 percent to 95 percent depending on the specific compound and mask type.

“Notably, OPEs exhibited a mean release percentage of 1.0 [percent], similar to phthalates, which showed a 1.2 [percent] release,” the researchers wrote.

The mask types with the highest overall release rates were surgical masks and FFP2s (3.9 percent and 4.8 percent, respectively). The reusable masks showed the lowest release rate, averaging 0.6 percent. The release rate of KN-95s was 1.2 percent. One surgical mask showed a release rate of one compound, acetyl tributyl citrate, a potential endocrine disruptor, of 95 percent.

Masks ‘An Additional Exposure Pathway’

Importantly, the values for the specific compounds the study tested for “remained below the established threshold limits,” the researchers wrote. However, plasticizers are present in more than just masks; they are commonly incorporated into toys, food packaging, clothing, cosmetics, cleaning products, and other items most people come into contact with daily.

Face masks “represent an additional exposure pathway that, when considered alongside other more predominant routes such as indoor/outdoor inhalation, dermal absorption, and dietary intake, makes the total exposure worthy of consideration,” the researchers wrote.

“Due to the proven exposure to plasticizers, the genotoxic, immunotoxic, and teratogenic [birth defect] risk remains regardless of the calculated values, particularly for children, pregnant women, and other risk groups.”

Plasticizers have been found in pregnant women’s blood and have been implicated in the dramatic drop in global sperm counts over the past 50 years, raising concern that these chemicals damage fertility and the health of future generations.