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  • Laser-based System Detects Asbestos in Real Time

Photonics.com
May 2013
HATFIELD, England, May 6, 2013 — Asbestos, once considered a miracle material because of its fire resistance, annually kills 100,000 people worldwide who inhale its fibers. Although banned in many industrialized countries since the 1980s, the threat lingers on in ceilings, walls and floors of old buildings. Now, a new laser-based system that is the first portable detector of asbestos aims to provide an affordable way for tradespeople to identify airborne particles.

This image shows light scattering from a thin-fiber particle illuminated by a laser beam.
This image shows light scattering from a thin-fiber particle illuminated by a laser beam. In this case the fiber is not asbestos. Light patterns such as these can be used to identify the shape and orientation of airborne particles. Courtesy of Paul Kaye, University of Hertfordshire, England.

Currently, the most common way to identify airborne asbestos at worksites is to use an air filter, count the number of trapped fibers, and use x-ray technology to determine if it is asbestos. This approach requires expensive lab work and hours of wait time. An alternative is to use a real-time fiber detector, but those commercially available are unable to distinguish between asbestos and less dangerous fibers such as mineral wool, gypsum and glass.

The University of Hertfordshire method employs a laser-based technique that exploits a unique magnetic property of asbestos: When exposed to a magnetic field, asbestos fibers orient themselves to align with the field, something virtually unique among fibrous materials. While the cause is still unclear, it is thought to be related to the amount of iron in the mineral.

A prototype asbestos detector unit with the lid removed.
A prototype asbestos detector unit with the lid removed. The prototypes are now undergoing field trials at various locations where asbestos removal operations are underway. Courtesy of Paul Kaye, University of Hertfordshire, England.

When light from a laser beam is shined at a stream of airborne particles, it bounces off, forming a complex scattering pattern. “We can use this technique of light scattering to detect single airborne fibers that are far too small to be seen with the naked eye,” said Paul Kaye, a member of the team that developed the new detection method at the University of Hertfordshire’s School of Physics, Astronomy and Mathematics.

After identifying the fibers, the detector carries them in an airflow through a magnetic field and uses light scattering again on the other side to tell if the fibers have aligned with the field.

The proposed design for the commercialized portable asbestos detector.
The proposed design for the commercialized portable asbestos detector. The 8- × 5- × 2-in. unit was designed by researchers at the Instituto de Biomecánica de Valencia (IBV), Spain. Courtesy of Clara Solves, IBV, Spain.

“If they have, they are highly likely to be asbestos,” he said.

The system has been lab tested, and the Hertfordshire team worked with colleagues in the UK and Spain to develop prototypes that are now in field trials. The team hopes that, over time, the new detector will help to reduce the annual death toll of 100,000 that the World Health Organization attributes to occupational exposure.

“Our colleagues estimate that it will take 12 to 18 months to get the first production units for sale, with a target price of perhaps $700 to $800,” Kaye said. That cost could come down as production increases after the initial launch, he added.

The detection method, developed under the European Commission FP7 project ALERT (FP7-SME-2008-2), was published in Optics Express.

For more information, visit: www.herts.ac.uk


GLOSSARY
detector
1. A device designed to convert the energy of incident radiation into another form for the determination of the presence of the radiation. The device may function by electrical, photographic or visual means. 2. A device that provides an electric output that is a useful measure of the radiation that is incident on the device.
spectrometer
A kind of spectrograph in which some form of detector, other than a photographic film, is used to measure the distribution of radiation in a particular wavelength region.  
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