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“The concentration we found is 100-fold higher than previous extrapolated estimates,” said authors Nadiia Yakovenko and Jeroen Sonke in , the peer-reviewed journal .

Plastic particles have been found all around us, from our water and food to the air we breathe. It has been found in almost every organ, including the brain, , and, yes, lungs.

“The findings from this paper make a lot of sense,” said Miriam Diamond, an environmental chemist and professor at the University of ÎÚÑ»´«Ã½ who is not affiliated with the study. “We know that we’re exposed indoors to plastic additives, but the mechanism (of exposure) was always a little bit questionable.”

How much plastic are you breathing?

The researchers, from the Université de Toulouse in France, took seven samples of air from their own homes and five from their cars. These were analyzed using a technique called Raman spectroscopy, to determine the concentration of microplastics suspended in air.

They counted a median 528 microplastics for every cubic metre of indoor space in the average home. In the car, the number quadrupled to 2,238 microplastics per cubic metre.

Out of these, 94 per cent were smaller than 10 micrometres in length — tiny enough to penetrate deep into the lungs.

Based on that, the team estimated that adults will inhale around 68,000 microplastics smaller than 10 micrometres while indoors every day, and about 3,200 plastics between 10 to 300 micrometres in size.

“People spend an average of 90 per cent of their time indoors, including homes, workplaces, shops, transportation, etc.,” the authors said. “All the while they are exposed to microplastic pollution through inhalation without even thinking about it.”

Wait, why do cars have so many microplastics?

Car cabins are small, often enclosed spaces mostly made of synthetic materials like plastic, from the dashboard to seat coverings.

These materials can shed tiny plastic particles as they go through the wear-and-tear of daily use, solar irradiance, friction and heat: “Just imagine a car that was baking outside during the heat wave,” Diamond said. “Temperatures can be extraordinarily high, so that’s going to promote a breakdown of plastic.”

Furthermore, are often more toxic because they contain greater levels of flame retardants, Diamond continued.

“Unlike homes, car cabins often have limited ventilation, allowing microplastic particles to accumulate and concentrate in the air,” the researchers continued. “As a result, they can be inhaled in higher amounts during regular commutes or long drives.”

Are microplastics bad for you?

The science is still out on exactly how microplastics are affecting our health, but there have been hints.

Evidence has linked the plastics and their additives to a , , ,Ìý, ,Ìý and more.

Much of the harm comes from the toxic additives they may carry, from dyes to UV blockers such as bisphenol A or phthalates,ÌýYakovenko and Sonke said.

“When microplastics are inhaled, these tiny particles can enter deep into our respiratory system and potentially cause inflammation or irritation,” the authors said.

Diamond added that the type of plastic and its shape also factor in. “A microplastic made of styrene is way more toxic than a microplastic made of polyethylene or polypropylene,” she said, while a sharp, jagged microplastic is more likely to cause damage than a round one.

The authors hope their findings could help guide public health recommendations, indoor air quality standards or even affect the products and materials we use in the future.

“I hope that our findings will raise awareness about indoor air as a significant source of microplastic exposure through inhalation,” they said.