How our detector works

How Asbestos is Currently Detected

Currently, the most common way to identify hazardous airborne asbestos at worksites is to filter the air, count the number of fibres that are caught, and later analyse the fibres with X-ray technology to determine if they are asbestos.

This approach requires expensive lab work and hours of wait time.

An alternative method to evaluate work site safety is to use a real-time fibre detector, but the current, commercially available detectors are unable to distinguish between asbestos and other less dangerous fibers such as mineral wool, gypsum and glass.

Lab Testing Asbestos

Alert's Method 

How it Works

ALERT's patented design analyses the airborne environment in real-time utilising both laser-light scattering technology, the paramagnetic properties of asbestos* and a unique algorithm to make a statistical analysis of the air it samples in real-time to 99.98% confidence.

Air is drawn in a controlled manner through the ALERT inlet at ~60ml/min, at up to 600 particles per second through a pair of laser beams and a magnetic field.

Spatial Light Scattering

When a particle is illuminated with a beam of light in ALERT's optical chamber, it will scatter the light in a pattern dependent on its size, shape, and structure. These patterns are like a thumbprint and are recorded and used to ascertain whether the particle is fibrous or not.

Asbestos fibres produce distinctive scattering patterns as can be seen in the examples below. However, the light scattering technique alone is not enough to differentiate between highly dangerous asbestos fibres and far less hazardous but generally more common fibres of, for example, glass or gypsum also commonly found in built environments.

Magnetic alignment

All fibrous particles are preferentially aligned vertically by ALERT's airflow and the system will measure the angle of alignment as it enters and then transits between the two laser beams.

The paramagnetic properties of all asbestos fibres mean that when exposed to a magnetic field asbestos fibres will try to align themselves. This change in alignment is measured by ALERT's algorithm enabling a distinction of asbestos fibres from other non-asbestos fibres passing through the optical chamber.

The schematic below illustrates ALERT's dual-beam asbestos warning system and the forward scattered light which is focused and recorded twice - once before and once after exposure to a magnetic field.

*Certain types of man-made fibre such as steel or magnetically engineered fibres may have similar magnetic properties to those of asbestos and could therefore be wrongly assessed as asbestos. However, unlike asbestos such fibres are not normally found in the ambient airborne environment where building, renovation or demolition work is being undertaken.

(Source: Light scattering pattern and schematic images below are courtesy of the University of Hertfordshire)



Laser scan

Schematic of ALERT dual-beam asbestos early warning system




Example of forward scattering patterns.

Top row: Background particles

Middle row: Crocidolite fibres

Bottom row: Chrysotile fibres


The company’s first model, the ALERT PRO 1000, is now market ready following a complete redesign to upgrade and enhance the system’s electronics, firmware and software ready for production.

The next model, the ALERT PRO 2000 with remote communications, GPS and mains power will follow within 6 months and a lower cost handheld model which gives a simple yes/no indication of whether asbestos fibres are present in the vicinity has been identified as the third model in the range to be developed.

A real-time detector of asbestos in solid materials (AsbestoProbe) has also been identified as another product to add to the family under a distribution agreement.

The price of the future smaller 'Tradesman's Model' has not yet been released but it is Alert Technology's aim to make the device affordable in line with other electronic instruments used regularly by the trade, with the hope that as production increases after the initial product launch, that costs may be reduced further making the detectors even more affordable for an individual plumber, electrician or building renovator.  

“These tradespeople are the most frequently affected by asbestos-related diseases and most who get the diseases will die from them,” the team says. 

The company have also identified a number of industry specific models for future development along with a Fixed Perimeter Model that works to clearance levels.



ALERT Technology hope, over time, the new Asbestos ALERT Device will help to reduce the 100,000 annual death toll that the World Health Organization attributes to occupational exposure to airborne asbestos.


British Lung Foundation


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