As a logical extension of our vision for environmental monitoring made simple, Texcel is adding dust monitoring to its suite of full-spectrum monitoring services. This addition is a direct response to inquiries from our customer base in the mining, quarrying, construction and infrastructure industries.
As we all know, demonstrating on-going compliance with DA or consent conditions is no small task, requiring, as it does, a constant balance between technical and human factors.
By incorporating dust monitoring into our suite of full-spectrum monitoring services, Texcel is able to take responsibility for all phases of the process from equipment selection, installation and maintenance to data management, security and graphical display.
Starting with a few basic issues:
We must start by admitting that all respirated dust should be considered harmful in some degree. Even if the dust levels are only a slight danger to the lungs, they are much more likely to have some adverse effect on the respiratory system – especially for asthmatics and allergy suffers.
Research has shown that the most harmful dust is less than 5 microns in size – i.e. 0.005mm!! This dust is not even visible to the human eye, but that doesn’t mean there is no danger. Just to put that number in perspective, a human hair is about 75 microns in diameter.
Particles of this size can contain things like nitrates, sulfates, metals, soil and many other things.
When dust-laden air is inhaled, most of the dust particles greater than 5 microns are captured in the mucus which coats the nose, sinuses, trachea, and bronchi – from here they are moved up with the mucus into the throat and swallowed or expectorated. But the particles less than 5 microns are actually passed into the lungs. From the lungs, some of the dust particles are exhaled, but others are absorbed into the lung tissue and this will eventually result in fibrosis of the lungs.
Hence there is a legal requirement to monitor the health of your workers whenever their work environment has the potential to exceed dust exposure limits.
The most harmful dust types:
While it is true that any type of dust is a potential risk, the most harmful types are silica, asbestos, sugar cane fibre, diatomite, talc and cotton dust.
So in the industries in which we normally work (mining, quarrying, construction and infrastructure), we are mainly concerned with silica and, sometimes, asbestos.
Dust monitoring parameters:
The parameter most frequently used is PM (particulate matter) followed by a number – e.g. PM2.5, PM10, etc. Sometimes TSP is also measured – total suspended particles
Understanding these numbers is somewhat counter-intuitive. The PM10 value, for example, is a measure of all particles less than 10 microns, PM2.5 is a measure of all particles less than 2.5 microns, etc. TSP measures all suspended particles less than 100 microns.
In all cases the unit of measure is µg/m3 – micrograms per cubic metre.
For example, the National Air Quality Standards set a PM10 limit of 50 µg/m3 per day and an annual average of 25 µg/m3 per day.
Monitoring instrumentation:
The instrumentation used to measure PM levels varies greatly.
By far the most accurate measurement is obtained from high-volume samplers. These units draw in air at a known flow rate through a filter for a determined amount of time and give a proper calculation of PM concentration. The catch is these instruments are large, expensive to purchase and run and require mains power to operate. Consequently, these types of monitors tend to be used for specialist applications – e.g. air quality monitoring networks, special studies, supersites, etc.
The more common instrument is a smaller, pole mounted, solar powered unit. These units are much less expensive to purchase and run and can be powered by solar panels. The catch is that their accuracy is generally ± 15%. This means that results are classified as indicative monitoring. These monitor types are much more generally deployed on construction, mining and quarry sites. They tend to focus on PM2.5 and PM10 dust fractions and use laser-based optical particle counters. They come in weather-resistant enclosures and are idea for 24 hour continuous monitoring. They integrate with Nexus by Texcel – a web-based portal for remote data access.
The Texcel full-service packages (Guardian and 360 by Texcel) provide a managed service that is completely turn-key. This absolves the operator/contractor of the responsibility of selecting, installing, maintaining, and reporting. Importantly, Texcel’s managed services provide an independent, expert, third party facility – i.e. environmental monitoring made easy.
