COMBATING AIRBORNE MICROPLASTICS IN THE WORKPLACE


They’re with you on every trip you take, every surface you clean, every outfi t you try out. Like the tagline for a bad horror fi lm, you can’t run and you can’t hide from microplastics. In particular, for those of us who work indoors, there’s no escaping plastic-based textile fi bres. Every year, European households consume about 60 million tons of the stuff, accounting for about 16% of global plastic production.1


the clothes that we wear and 70% of our tea-towels, quilts, curtains and cushions are plastic-based.2 And production is increasing – by about 6% each year.


What are microplastics?


To be precise, microplastics are solid synthetic particulates or polymeric matrices of varying shape that measure somewhere between 1 mm and 1 µm, all of which are insoluble in water.3 Sometimes, microplastics are deliberately produced, as in the microbeads which are ubiquitous in cosmetic products. Otherwise, they are the result of larger plastics degrading – and that’s what has the experts most on-edge.


For instance, a study of settled dust in households found that carpeted homes had more than double the amount of fi brous polyethylene, polyamide, and polyacrylic in the air than places without carpeting. Yet, worryingly, while they might be spared these particular microplastics, the long-term degradation of coating applied to most hard fl ooring ensures that these homes have a greater concentration of polyvinyl fi bres than their carpeted counterparts.4


What’s the harm?


When it comes to plastics, it’s what’s added to the compound – to give it extra strength, a certain odour, decreased fl ammability,


etc. – which is worrying. Most additives leach from the surfaces of microplastics once ingested because they are not bound to the plastic polymers. In particular, the additives of concern are the phthalates and bisphenol A (BPA), all of which disrupt the human endocrine system.


Take benzyl butyl phthalate, or BBP, a plasticiser used in everything from food containers and electrical wires to fl oorings and paints. Owing to their endocrinal effects, most phthalates are linked to insulin resistance and are classifi ed as xenoestrogens.5


All of


this also applies to bisphenol A (BPA), which has been hardening plastics since 1957.6


Aerial threat


The troubling fact is that we are inhaling plastics treated with BBP and BPA at a higher rate when we’re indoors – current concentrations range from 1.6 to 12.6 microplastic particles per m3


.7


By far and away, synthetic textile fi bres – particularly polyamine, a.k.a. nylon, and polyester fi bres -are the most abundant microplastics in indoor air. Many of the clothes that we all wear to the offi ce will be made from synthetic materials, from which thousands of tiny fi bres easily tear over the course of a day. But all sorts of everyday tasks, from the opening of plastic packaging to using a printer, spit out other microplastics, like degraded polypropylene and polyethersulfone, into the offi ce air.8


Of course, there are simple safe- guarding measures that can be put in place immediately, like increased ventilation – in fact, many workplaces already take similar precautions for COVID-19.9


And other measures,


like redistributing offi ce space to allow for greater distance between workstations, may be more expensive, but as we all continue to split time between home and offi ce, this might not even require any extra


square-footage, just a bit of extra scheduling.


But, in the interests of health and safety, however, it’s important to characterise and quantify airborne microplastics – especially those which measure 2.5 µm in diameter or smaller, because at this size they can breach the lung barrier and enter the bloodstream.


Measuring airborne microplastics


As you descend below 500 µm, though, background interference by organic compounds will scupper analysis of untreated samples. There are a few chemicals capable of neutralising this interference, but the current vogue is to treat samples with sodium hydrochlorite or a 30% hydrogen peroxide.10 Usually, after treatment, a solution of zinc chloride, with a density between 1.6 - 1.7 g/cm3


, is used to separate components, including microplastics of different types.11


In order to identify the particulates, it is customary to follow a two-step process. Firstly, using a stereomicroscope with an imaging analysis software, study the shape of the microplastics in the sample, which should provide a cursory understanding of their origin. If you observe thin fi bres, the culprit is clothing and furniture; if you can see fragments, they’re the degradants of larger plastics like food containers, bin-liners and electrical appliances.


Secondly, an analysis of the polymeric composition of your microplastics, which will help to identify toxicological risks, is commonly conducted using Fourier-Transform infrared spectroscopy (FTIR). Using infrared light, this non-destructive spectroscopic method turns the absorption rates of the components into a spectrum, according to the Fourier Transform function, and digitally cross-references to identify the polymers. Although FTIR instruments are relatively expensive and require skilled technicians, the method produces reliable results with small samples.


Another popular choice is a combination of Raman spectroscopy and spectral imaging equipment, in which a uniform-wavelength laser is refl ected, scattered, and absorbed by a sample, producing a unique fi ngerprint for each component. Although this method boasts the unique ability to detect microplastics all the way down to 1 µm, it suffers from a fair amount of interference (particularly, high background fl uorescence) and the libraries of the instruments are currently under-developed.


Nevertheless, information about how to measure airborne microplastics is still very limited, but the dangers of overexposure


IET JANUARY / FEBRUARY 2022 In fact, it has been estimated that around 60% of


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