Tiny plastic particles surround us daily. We can’t see them, but we inhale the plastic dust constantly.
A new study by Nadiia Yakovenko and colleagues at Université de Toulouse uncovers how much more exposure we face indoors than previously assumed.
Published in the journal PLOS ONE, the research reveals just how dense microplastic pollution has become inside homes and vehicles.
Earlier studies showed that plastics float in the air almost everywhere. These fragments, called microplastics, often come from synthetic clothes, car interiors, packaging, and household items. Indoor air contains more of them than outdoor air.
Until now, most research focused on larger particles that rarely enter deep lung tissue. This study takes a sharper look at smaller particles – the ones that can reach the lungs.
Tiny plastics harm your lungs
When particles are smaller than 10 micrometers (µm), or 0.0004 inches, they become a threat to deep lung tissue. They slip past our natural filters and can reach the bronchi and even enter the bloodstream.
These particles also carry toxic chemicals and pollutants. Once inside the body, they may harm vital systems.
Yakovenko’s team studied both apartments and cars using Raman spectroscopy, a method capable of detecting particles as small as 1 µm. They found that the average indoor air contains thousands of these tiny particles per cubic meter.
Homes and cars had different compositions. Polyethylene dominated in homes, while polyamide was more common in cars due to the types of fabrics and plastics used in vehicle interiors.
Smaller particles, bigger problem
Most previous studies used µFTIR spectroscopy, which detects particles no smaller than 10 µm. This left out the most common size range found in indoor air.
The new study used a more sensitive method and found microplastic concentrations up to 100 times higher than earlier estimates.
More than 90% of all detected particles were smaller than 10 µm. These particles followed a pattern where smaller particles appeared more often.
The distribution pattern followed a power law, meaning particle numbers rose sharply as size dropped. That means we are breathing in large quantities of the smallest, most hazardous plastics.
Indoor dust is mostly plastic
Sampling revealed a median of 528 particles per cubic meter (~15 particles/ft³) in homes and 2,238 particles per cubic meter (~63 particles/ft³) in cars.
These particles were mostly fragments rather than fibers. Their size typically ranged from 1 to 10 µm.
Based on combined data from this and other studies, researchers estimated that adults inhale about 3,200 larger microplastics and 68,000 smaller ones on a daily basis.
These smaller particles can cross biological barriers, reach the bloodstream, and impact organs. They may also release additives and chemicals that disrupt hormones and affect immunity.
Role of the gut and beyond
Larger particles usually get trapped in mucus and are removed by coughing or swallowing. This process introduces plastics into the digestive system.
This secondary ingestion route could rival or exceed plastic exposure from food and drinks. In fact, people may absorb more microplastics through air than through meals.
Children may be even more vulnerable due to higher air intake relative to their body weight. Inhalation rates vary, but on average, children may inhale up to 47,000 small plastic particles daily. These particles can reach places in the body where they don’t belong.
Plastic dust found everywhere
“We found that over 90% of the microplastic particles in indoor air across both homes and cars were smaller than 10 µm, small enough to be inhaled deep into the lungs,” noted the researchers.
This was also the first study to measure microplastics in the car cabin environment. Overall, the team detected indoor concentrations up to 100 times higher than previous extrapolated estimates, revealing indoor air as a major and previously underestimated exposure route of fine particulate microplastic inhalation.
“Everywhere we looked, we find microplastics, even in the air we breathe inside our homes and cars,” the researchers said.
The biggest concern is how small these particles are completely invisible to the naked eye. “We inhale thousands of them every day without even realizing it,” the team pointed out.
Deep inside our lungs, microplastics release toxic additives that reach our blood and cause multiple diseases.
Next step in microplastic research
This study also estimates potential exposure to nanoplastics, which are particles smaller than 1 µm (0.00004 inches). These may reach even deeper parts of the lungs and possibly cross into cells.
Though no direct measurements were made, the study extrapolated a likely exposure rate of over 33 million nanoplastics per day in the smallest size range.
Inhaled nanoplastics may behave differently than microplastics. They are smaller, more reactive, and harder to detect. Future research must develop better ways to observe and measure these invisible invaders.
The takeaway is clear. Indoor air carries more microplastics than we assumed, especially in the most harmful size ranges.
This study urges regular monitoring and a closer look at how these particles move, settle, and affect health. Until then, the invisible plastic dust in our homes and cars remains an open hazard. We breathe it in with every passing moment.
The study is published in the journal PLOS One.
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