Small but mighty: Benchtop XRD and XRF for accurate air particulate analysis

Going outside for a breath of fresh air always sounds like a good idea – and maybe even a healthy decision. After all, it’s easy to ignore that column of smog billowing out of a factory chimney far in the distance. But the reality is that, in today’s industrialized world, the fresh air we have in mind doesn’t really exist. Air pollution is everywhere, indoors and outdoors, with 99% of the global population breathing air that contains high levels of pollutants.

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Perhaps because we can’t often see them, the presence of toxic pollutants in the air around us is an often-overlooked aspect of the environmental crisis. Indeed, these pollutants don’t stay in the air around us. Instead, humans can inhale particulates with a diameter below 10 μm (known as PM10 and PM2.5), causing severe, chronic, or even fatal health problems, many of which are related to our respiratory and cardiovascular systems. In fact, together, indoor and outdoor forms of air pollution are associated with 7 million premature deaths every year.

Many of the factors that contribute to air pollution are also sources of greenhouse gas emissions. This is obviously a major problem, but from another perspective, it’s also good news: with all eyes on the 1.5-degree global warming threshold, actions to reduce emissions and protect our struggling planet are being accelerated. Efforts to phase out pollution sources and bring in cleaner solutions will also have a positive impact on air quality – and thus on human health.

Digging into RCS regulations

Of course, some people are still more at risk than others. Respirable crystalline silica (RCS), for instance, commonly in the form of airborne quartz dust, is high on the health and safety agenda for mining, construction, and other mineralogical-related operations. The effects of prolonged inhalation of RCS can be serious, and businesses whose employees are exposed to this risk have a responsibility to monitor air quality.

This is driven in part by changing regulatory demands. As the scope and severity of the air pollution problem becomes better understood, requirements – such as the US Environmental Protection Agency (EPA) IO-3.3 norm – are being stepped up by governments and other authorities. Nevertheless, occupational exposure limits for RCS vary between countries, although 0.05 mg/m3 per 8-hour shift has now become the maximum in both the USA and Australia.

The first step toward complying with these and other air pollution standards, and ensuring safe working conditions for employees, is to undertake regular and accurate monitoring of particulate levels. Enter X-ray diffraction (XRD) and X-ray fluorescence (XRF): two straightforward and non-destructive techniques for these important analyses.

Why size can be misleading: Aeris 600 W

When it comes to the quantification of RCS in particular, XRD is the preferred method. The strength of this technique lies in its superior sensitivity, meaning it can comply with ever-decreasing RCS exposure limits and effectively handle phase interference in complex mineralogical matrices. Traditionally, floor-standing XRD instruments have been preferred over compact alternatives – but as the performance of compact XRD tools improves, the tide is turning. Not only are compact instruments competitive on performance, but they also offer operators the advantages of being less demanding in terms of costs and infrastructure requirements.

Malvern Panalytical’s benchtop Aeris 600 W diffractometer is a prime example. In a comparison study between the Aeris and our floor-standing Empyrean 1.8 kW diffractometer, both were shown as having sufficient sensitivity for testing filters in line with RCS regulations – despite the Aeris 600 W’s more compact size, simplified optical path, and lower operating power.

Short-range XRD patterns measured around the primary quartz (RCS) peak.

The results show that, while our Empyrean may meet higher throughput requirements as well as serving other X-ray scattering applications, our compact Aeris instrument is the ideal cost-effective alternative for those seeking XRD with a smaller footprint. As RCS regulations ramp up, accessible solutions like the Aeris 600 W become ever more valuable, ensuring both the security of mineralogical operations and the safety of workers.

Calibrated for compliance: Epsilon 4

XRF, meanwhile, is another popular method for air pollution sample testing – and Malvern Panalytical’s Epsilon 4 benchtop instrument is another small-scale, big-impact solution. In its factory calibration (set up to analyze 46 elements, from Na to U), this XRF tool is fully compliant with EPA IO-3.3, meaning there’s no need for operators to invest in expensive, large-scale tools.

The Epsilon 4 is a unique solution for elemental analysis of air particulates, delivering results in 45 minutes for up to 10 samples at a time. Crucially, when it comes to the all-important lower limit of detection (LLD), the Epsilon 4 proves size doesn’t matter: test results show it has a lower LLD across the board in comparison to the values reported in the EPA method, demonstrating our solution’s superior sensitivity.

Expertise at your fingertips

In the mining industry, there can be no compromise on safety. With Malvern Panalytical’s high-quality compact monitoring instruments, you can rest assured of having full oversight into any air pollution risks in your operations, all while keeping investments to a minimum and valuable floor space clear. What’s more, no matter which of our powerful tools you choose, our experts are always on hand to offer support and guidance – so you can breathe easier.

Contact our Malvern Panalytical experts to discover how XRF and XRD can help you comply with tougher air particulate regulations.