Understanding Airborne Microplastics and Their Health Effect

In 2004, marine biologist Professor Richard Thompson and his team from the University of Plymouth became the first to demonstrate that microplastics ‒ minuscule plastic particles measuring less than five millimeters ‒ had been accumulating in the oceans for decades.¹ Their research revealed that microplastics had spread throughout marine ecosystems across the globe, highlighting a growing and persistent environmental issue.

While initially thought to be confined to water, we now know microplastics can be found in every part of the environment, including the air we breathe.² Most airborne microplastics are less than one millimeter in length and are classified depending on their shape ‒ fibers (long and thin) or non-fibers.³ Their shape, color and polymer type are influenced by the original plastic source.

In this article, we examine airborne microplastics in greater detail, explore detection methods, consider what we currently know about their health risks and highlight various mitigation strategies.

Unpacking the origins of microplastics

Airborne microplastics are a growing concern due to their presence across diverse environments, from lively city centers to isolated, untouched corners of the world.

“Microplastics are found throughout the environment, including remote and high-altitude areas, and have been detected in various forms such as indoor and outdoor air, dust and snow,” explained Professor Kevin Thomas, director of the Queensland Alliance for Environmental Health Sciences (QAEHS) at the University of Queensland. His work explores the risks posed by microplastics and other contaminants of emerging concern.

These particles originate from various sources and are categorized into primary and secondary microplastics. Thomas elaborates: “Primary sources are microplastics intentionally manufactured to be small, such as microbeads in cosmetics, and secondary sources result from the breakdown of larger plastic items through processes like weathering and abrasion.”

“In urban environments, secondary sources are more prevalent due to the high levels of plastic waste and activities that contribute to plastic degradation, such as emissions from traffic and industrial activities,” added Thomas.

Primary vs secondary microplastics

Along with these more commonly recognized sources of microplastic pollution, agricultural practices and other human activities can also play a role. For example, biosolids (a wastewater byproduct used as a fertilizer) are a known source of airborne microplastics.⁶

Figure 1: Distribution and fate of airborne microplastics. Credit: Technology Networks, adapted from Airborne Microplastics.

Home is where the… plastics are

The concentration of airborne microplastics can vary significantly depending on whether you are indoors or outdoors ‒ indoor spaces tend to have much higher levels.

A 2021 study examined twenty homes in the Humber region of England over a six-month period. The concentration of atmospheric microplastics inside the homes was found to be up to 45 times higher than levels detected outdoors.⁷  This observation has also been demonstrated in other locations across the globe.^8,9

“This [increase] is due to sources like synthetic textiles, carpets and household dust,” Thomas noted.

A review paper by Thomas and colleagues indicated that synthetic textiles like carpets and upholstery release microplastic fibers into the air as they degrade. Everyday activities, such as vacuuming or simply walking room-to-room, can also disturb settled microplastic particles, causing them to become airborne. While properly functioning ventilation systems can help reduce the concentration of airborne microplastics, the study found that poorly designed or faulty systems may release previously trapped microplastics and recirculate them.¹⁰   

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Detecting and measuring airborne microplastics

Currently, a lack of consistent methods for measuring airborne microplastics creates challenges, such as the inability to compare data across studies.

“Microplastics are challenging to measure because they are not just chemicals but physical objects,” said Dr. Matthew Campen, head of the cardiovascular toxicology laboratory in the department of pharmaceutical sciences at The University of New Mexico. His work focuses on understanding the cardiovascular health effects of inhaled pollutants.

There are several analytical techniques that can be used for airborne microplastic analysis, each with its own strengths and limitations.

Thomas highlights a few: “Microscopy is widely used for visual identification and counting. It is straightforward but can be time-consuming and may miss smaller particles. Spectroscopy (e.g., Fourier-transform infrared (FTIR), Raman) helps identify the chemical composition of microplastics… whether it’s a polymer or not. Mass spectrometry (e.g., pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS)) provides detailed chemical analysis. It is sensitive but an indirect technique and potentially subject to interferences.”

Exposure and health risks

Emerging evidence suggests that microplastics can accumulate in human organs, blood and breast milk. Microplastics also carry chemical additives and can adsorb environmental pollutants (e.g., heavy metals) and biological agents (e.g., bacteria and viruses) allowing them to enter human cells and tissues when inhaled or ingested.^{12,13 14}

While the health effects of microplastic exposure remain largely unclear, studies suggest potential links to cardiovascular disease and inflammatory bowel disease.^15,16

“Despite the growing number of studies, significant knowledge gaps remain, particularly in understanding the atmospheric fate, behavior and toxicity of microplastics ‒ there is an urgent need for standardized mass-based quantification and comprehensive toxicity assessments,” said Thomas.

Three main routes into the body

While we need robust analytical methods to study microplastics in the atmosphere, these techniques are also crucial for understanding microplastics’ behavior within the human body once inhaled, ingested or absorbed through the skin.¹⁷

It may seem counterintuitive at first, but inhalation is likely not the primary route of exposure to airborne microplastics, Campen notes. Ingestion poses a greater risk for micro- and nanoplastic uptake, although smaller particles are more likely to be a respiratory concern. “Certainly, the most relevant particles will be <1 µm, and maybe 100‒200 nm is the major concern,” he said.¹⁸

How microplastics influence lung health

Most research on the physical and chemical toxicity of inhaled microplastics to date has been conducted using in vitro test systems, Thomas noted: “In vitro studies suggest that these particles can induce inflammatory responses and oxidative stress in lung tissues, but I would question whether the model microplastics used are representative of what we are being exposed to.”

“Before it’s possible to comment with any certainty of the physical and chemical toxicity of inhaled microplastics we need to understand what we are being exposed to ‒ sound particle characterization ‒ and establish where these particles are ending up,” added Thomas.

Thomas’ points resonated with Campen: “They [microplastics] have physical characteristics that influence their uptake and travel within the body. Thus, there are valuable approaches such as FTIR and Raman spectroscopy that can visually identify plastic particles and confirm their polymer chemistry, but such techniques are typically limited to particles larger than 5 µm.”

He continues: “The recent surge in the use of Py-GC-MS reflects a need to more cumulatively assess plastics of all sizes in the body, most of which are below 1 µm.”

Beyond the lungs: bioaccumulation in other organs

Campen has been using Py-GC-MS to study the bioaccumulation of microplastics in various human organs, including the placenta and brain.^19,20* One of these studies, published in Toxicological Sciences found microplastics in every human placental tissue sample tested, with concentrations ranging from 6.5 to 790 µg/g.¹⁹

In a recent preprint, Campen and colleagues analyzed micro- and nanoplastic particles in post-mortem samples of human liver, kidney and brain collected from deceased individuals in 2016 and 2024. The team discovered that the brain samples had higher concentrations of particles compared to the liver and kidneys, with all organs showing increases over the years.^20*

Campen is optimistic that, with more experience and optimization, Py-GC-MS will give researchers a better path to linking exposures to plastics with health outcomes: “Py-GC-MS assesses the total mass concentration of plastics – that is in µg/g. This does not tell us much about the size, but when we consider linking chemicals to health effects, we always use mass concentration. This approach also affords a nice way to look generally at a lot of different kinds of polymers, identifying polyethylene, polypropylene, etc.”

Despite its benefits, Campen cautions that Py-GC-MS is not yet a “settled science”, and it’s important to acknowledge that many questions remain regarding the specificity results for polymers.

“Many chemists and health scientists around the planet are currently working to optimize this approach to ensure that we have confidence in this technique,” said Campen.

A unified approach to mitigating microplastics

Mitigating airborne microplastics requires a multifaceted approach, from better individual choices in daily life to novel product innovations, updated industry regulations and government policies. Researchers are striving to bring about positive change across all levels ‒ from individuals to organizations and policymakers ‒ all of whom play a role in reducing the formation and spread of microplastics into the atmosphere (Table 1).

In a correspondence article published in Nature Medicine, Thomas and colleagues highlighted the harmful effects of plastics and stressed the need for urgent action ‒ such as banning hazardous chemicals, reducing the use of microplastics in products and prioritizing research into their health risks.¹²

Table 1: Key strategies for mitigating airborne microplastics.