The presence of microplastics in the air is a growing environmental concern. Microplastics are defined as tiny fragments of plastic polymer that are typically less than five millimeters in size. These minuscule pieces are a heterogeneous collection of fragments, spheres, and fibers, including synthetic polymers like polyethylene terephthalate (PET) and polyethylene (PE). Their discovery in remote areas and within human tissue highlights the global nature of this pollution.
Where Airborne Microplastics Originate
Airborne microplastics originate from a variety of sources, with the majority being secondary microplastics—fragments resulting from the breakdown of larger plastic items. A significant source in the outdoor environment is the mechanical abrasion of vehicle tires on roads, which sheds particles into the air as a form of non-exhaust emission. These fragments, along with plastic dust from industrial processes and the fragmentation of plastic litter, become easily aerosolized and transported by wind currents. Indoors, the primary source is synthetic textiles, such as clothing, carpets, and upholstery. Fibers shed from these materials during normal wear, movement, and especially during the laundry process. These fibers then settle into household dust, which can easily be resuspended into the air through daily activities like walking or vacuuming. Atmospheric modeling indicates the marine environment acts more as a sink, absorbing microplastics from the air, meaning that most airborne particles originate from land-based activity.
How Scientists Detect and Track Them
Scientists use specialized methods to confirm the presence of airborne microplastics and identify their chemical composition. Sampling often involves high-volume air filtration systems that draw in large amounts of air, capturing the suspended particles onto a filter medium. Once collected, researchers must chemically or physically separate the plastic from other organic and inorganic matter, a process that can be challenging due to the small size and low mass of the particles. Identifying the polymer type is achieved through various spectroscopic techniques. Fourier-transform infrared (FTIR) spectroscopy is commonly used, providing a spectral “fingerprint” of the chemical bonds within the plastic, allowing for identification of the polymer. Raman spectroscopy offers a complementary method, often preferred for analyzing particles smaller than 10 micrometers. The widespread distribution of airborne microplastics has been confirmed, with particles being detected in environments as isolated as the high-altitude mountains and polar regions.
Health Risks of Inhaling Microplastics
The inhalation of microplastics represents a significant exposure pathway, with the health consequences dependent on particle size and shape. Particles larger than 10 micrometers are typically captured in the upper respiratory tract, such as the nasal cavity and the back of the throat, where they are often cleared by the body’s natural defense mechanisms. However, smaller particles, particularly those under 2.5 micrometers, can penetrate deep into the lungs and reach the alveoli, the tiny air sacs where gas exchange occurs. Once lodged in the deep lung tissue, the presence of these foreign materials can trigger biological responses. Studies suggest that microplastics may induce local inflammation and oxidative stress, a cellular imbalance that can lead to tissue damage. This inflammatory response is a particular concern for individuals with pre-existing conditions like asthma or chronic obstructive pulmonary disease (COPD), as exposure may exacerbate their symptoms. Microplastics can carry an array of chemical additives, such as phthalates and bisphenols, which can leach out once inside the body. These leached chemicals introduce toxicity, interfering with endocrine function or contributing to systemic effects.
Steps for Personal Reduction
Focusing on the home can reduce personal exposure, as indoor environments contain higher concentrations of microplastics than outdoor air. The use of high-efficiency particulate air (HEPA) filters in air purification systems is an effective strategy, as they capture particles as small as 0.3 micrometers, removing most airborne microplastics. Integrating HEPA filtration into vacuum cleaners also prevents microplastic-laden dust from being recirculated back into the air during cleaning. Reducing the generation of fibers from synthetic textiles is important because they are a major indoor source. Choosing natural fibers like cotton, wool, or linen for clothing, bedding, and home furnishings minimizes the shedding of plastic material. For existing synthetic clothing, using specialized laundry bags or installing a microfiber filter on the washing machine can trap shed fibers. Regular dusting with a damp cloth and wet mopping also prevents the accumulation of settled microplastic dust.