Researchers study how many particles people breathe indoors
A new scientific study shows that indoor air contains large numbers of tiny plastic fragments, most of which are small enough to enter deep parts of the lungs. The research team collected air samples from several apartments and car cabins in France. Their goal was to count and study the smallest plastic pieces in indoor air.
The results suggest that people inhale tens of thousands of plastic particles each day, with more coming from cars than homes. These plastics are too small to see and float in the air just like dust. Once inhaled, they can reach the lower lungs or even enter the bloodstream.
Smaller particles were not measured before
Past studies focused on larger particles, often bigger than 10 micrometers. These were easier to detect but less likely to reach the deep lung. In this study, researchers used a high-precision tool called Raman spectroscopy. This method can find particles as small as 1 micrometer, which is about one-hundredth the width of a human hair.
Using this tool, the researchers could study the full range of inhalable particles. They focused on the 1 to 10 micrometer range, which can go deep into the lungs and may stay in the body for a long time.
Car cabins had the highest concentrations
The team tested indoor air in two types of places: regular apartments and car interiors. Both types had plastic fragments, but car cabins showed much higher numbers. In cars, the average count reached 2,238 plastic particles per cubic meter of air. In homes, the average was about 528 particles per cubic meter.
One of the reasons for this difference is the type of material found inside vehicles. Seats, panels, and other surfaces in cars are often made from synthetic materials. These materials wear down over time. Heat, friction, and sunlight can cause them to release plastic fragments into the air. Cars are also closed spaces with limited airflow, which makes it easier for these particles to build up.
Most of the particles came from common plastics
The study found that the types of plastics in indoor air matched the materials found in furniture, textiles, and vehicle parts. In homes, most of the particles were made from polyethylene. This is a plastic commonly used in packaging and containers. In cars, polyamide and other plastics used in upholstery were more common.
The researchers analyzed the particles using their shape and size. Almost all of the plastic bits appeared as irregular fragments. Only a few were long, thread-like fibers. The study focused on suspended particles in the air, not settled dust, so it captured only what people could breathe in.
Inhalation estimates were much higher than expected
Based on the measured concentrations and average breathing rates, the team estimated how many plastic particles people inhale. Adults breathe about 68,000 of these small particles per day from indoor air. Children inhale around 47,000 daily. These numbers apply to indoor environments only and do not include outdoor air.
Most earlier studies had placed this number closer to a few hundred particles per day. But those were based on larger fragments. This new study suggests those estimates missed a large portion of exposure.
Particles could also affect other parts of the body
Not all inhaled particles stay in the lungs. Larger pieces often get caught in the upper airways. These are cleared out by coughing or swallowed with mucus. This means some of the plastic also enters the stomach and intestines.
Plastic fragments in the air can also carry harmful chemicals. Many plastics include additives that make them flexible or long-lasting. These chemicals can come loose inside the body and may affect hormones or other systems. The study did not test health effects directly but explained how these exposures could lead to risks over time.
Nanoplastics might be even more common
The team focused on particles between 1 and 10 micrometers. But they also used mathematical models to estimate how many nanoplastics might be present. These are even smaller than 1 micrometer. Based on their models, indoor air may contain millions of nanoplastic particles per cubic meter.
There is still no standard way to detect particles that small, so more research is needed to confirm those numbers. But if the estimates are close, nanoplastics may be the biggest part of daily exposure.
New detection method gave clearer results
One reason this study produced different numbers is the method used. Raman spectroscopy allows for analysis of very small areas in great detail. The process was slow. Each sample took more than 14 hours to scan. Because of this, the researchers could only test a small number of samples. But each one provided thousands of readings and very accurate data.
Most other studies use infrared tools that cannot detect fragments below 10 micrometers. These tools are faster but miss a large part of the particle spectrum. As a result, they often underestimate how many plastic bits are in the air.
Many factors still unknown
This study gives new data on indoor exposure but also shows how many questions remain. The research focused on two types of spaces, both in one region of France. Larger studies are needed to see how results change in other climates, buildings, or lifestyles.
The team also said that indoor exposure depends on many things, such as how often people clean, what materials are inside, and how much time they spend in each space. They suggest future work should look into those variables in more detail.
Conclusion from the findings
The results show that indoor air contains more microplastics than previously believed. The number of particles small enough to reach deep into the lungs is high, especially in vehicles. These exposures may pose long-term health risks. The study recommends using better detection tools and collecting more data across different environments.
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