Humans are likely inhaling far greater amounts of lung-penetrating microplastics than previously assumed, scientists are warning.
People may be breathing in about 100 times more of these tiny fragments than past estimates indicated — from sources based both outside and indoors, including in homes and cars, researchers revealed in a new study, published on Wednesday in PLOS One.
These tiny, inhaled particles can invade the lungs and cause oxidative stress, while wreaking havoc on the immune system and other organs, according to the study authors.
“Everywhere we look, we find microplastics, even in the air we breathe inside our homes and cars,” they said in a statement. “The biggest concern is how small these particles are completely invisible to the naked eye.”
While research has thus far largely focused on larger microplastics ranging from 20 to 200 micrometers in diameter, the study authors — from the Université de Toulouse in France — decided to focus on those 10 micrometers or less, which penetrate the lungs more easily.
“Something we can’t see can still harm us,” co-lead-authors Nadiia Yakovenko, a postdoctoral scholar at the university, and Jerome Sonke, a research director at the French National Center for Scientific Research, said in joint remarks.
“Our findings show that microplastics in the air, especially indoors, may be an invisible threat we are only beginning to understand,” Yakovenko and Sonke added.
To better quantify the typical number of inhaled microplastics, the scientists said they collected air samples from their own apartments and cars, under realistic driving conditions. The researchers then employed a technique called Raman spectroscopy, through which they measured concentrations of microplastics in 16 air samples.
The median concentration of detected microplastics was 528 particles per cubic meter in the apartment air samples and 2,238 particles per cubic meter in the cars, with 94 percent of all detected particles measuring less than 10 micrometers.
“We inhale thousands of them every day without even realizing it,” the authors said. “Deep inside our lungs, microplastics release toxic additives that reach our blood and cause multiple diseases.”
After combining their results with previously published data regarding indoor microplastics, the researchers estimated that adults inhale about 3,200 microplastic particles in the 10-300-micrometer range daily.
But they also found that these same individuals breathe in about 68,000 particles of 1-10-micrometer particles per day — more than 100 times more than previous research estimated for these small-diameter fragments.
These findings, the authors stressed, suggest that health risks from inhaling lung-penetrating microplastic could be much higher than previously thought. As such, they called for more research into this critical question.
Yakovenko and Sonke, the co-lead-authors, expressed particular concern about car cabins, which they stressed have limited ventilation — enabling microplastic particles to accumulate and concentrate in the air. Under these circumstances, they explained, people can inhale microplastics in greater quantities during long commutes.
The two researchers said they hope that by raising awareness about this issue, their study could help guide future public health recommendations and indoor air quality standards. Their team, the scientists continued, plans to assess a wider variety of indoor exposures and relevant daily habits.
“We hope to shed light on a more personal and constant route of microplastic exposure through inhalation that has so far remained under the radar,” they added.
