Microplastics in air: Are we breathing it in?
Graphical abstract
Introduction
Plastic pollution is an emerging concern worldwide, with the majority of studies focusing on microplastics (MPs; plastic particles with a longest dimension < 5 mm) in marine, and more recently, continental environments. Worldwide plastic production increases annually by approximately 3%, and, excluding plastic fiber production, reached 322 million metric tons in 2016 [1]. Whilst the ubiquity of MPs, and especially of fibrous MPs in both marine and freshwater ecosystems has been demonstrated, the dynamics of their sources, pathways and reservoirs are not well documented. Among the sources of microplastics, urban inputs such as wastewater treatment plant effluents are increasingly studied while the atmospheric comportment is mostly neglected. If present in sufficient quantity, the question of their inhalation and associated health risks will be an important issue. Focusing on fibrous MPs, this paper addresses both issues by reviewing work undertaken on the occurrence of MPs in the atmospheric compartment as well as discussing human exposure and the potential for subsequent health risks.
Section snippets
Airborne MPs: is there an issue?
In air, different kinds of fibers can be found. A general classification of fibers is given in Table 1. Fibers can be either natural or man-made. Man-made fibers can also be classified as inorganic (carbon, ceramic, glass) or organic. In this latter category, organic fibers are produced by transformation of natural products (artificial fibers) or from synthetic polymers (Table 1).
Worldwide, more than 90 million metric tons of textile fibers were produced in 2016. Two thirds of this production
Are airborne fibrous microplastics breathable?
The likelihood that airborne fibrous MPs enter our respiratory system will be dependent upon size. First, it is important to discriminate between the terms inhalable and respirable. Particles and fibers able to enter the nose and mouth and deposit in the upper airway are inhalable, whilst those able to reach and deposit in the deep lung are respirable. Deposition in the airway is a function of aerodynamic diameter and within the respiratory zone, deposition falls off above 5 μm diameter [11].
Recommendations
There is an urgent need for data on the human health impacts of fibrous MPs. However, before this is determined, it is important to better assess whether and if so, how we are exposed. To this end, collaboration between environmental, epidemiological and air quality communities is required to set up relevant research programmes, which include specific monitoring strategies. Both length and diameter should be included when reporting on the presence of MPs since diameter is crucial to
Conflict of Interest
Nothing declared.
References (0)
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shared first authorship.