Measurement

In workplace atmospheres

To measure dust exposure levels at the workplace, the following European standards provide the necessary technical guidance to implement a dust monitoring strategy:

EN 689: Workplace atmospheres-Guidance for the assessment of exposure by inhalation to chemical agents for comparison with limit values and measurement strategy, 1995, CEN.

EN 1232: Workplace atmospheres-Pumps for personal sampling of chemical agents-Requirements and test methods, 1997.

To determine the quartz/cristobalite content in the collected dust, two different analytical techniques can be used: Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD).
Here are the reference standards for both techniques:
AFNOR- XP X 43-243 : Dosage par spectrométrie infra rouge à transformée de Fourier de la silice cristalline - Echantillonnage par dispositif à coupelle tournante ou sur membrane filtrante.
AFNOR XP X 43-295 : Détermination par rayons X de la concentration de dépôt alvéolaire de silice cristalline- Echantillonnage par dispositif à coupelle rotative.
MDHS 101:  Crystalline silica in respirable airborne dusts- Direct-on-filter analyses by infrared spectroscopy and X Ray diffraction.
NIOSH 7602: Silica, crystalline by IR.
NIOSH 7500: Silica, crystalline by XRD.

Industry dust monitoring protocols:

A dust monitoring protocol is provided in Annex 2 of the Social Dialogue Agreement on Workers’ Health Protection through the Good Handling and Use of Crystalline Silica and Products Containing it, see www.nepsi.eu. It summarises the general requirements from the European Standards EN 689 and EN 1232 mentioned above.

IMA-Europe has developed its own Dust Monitoring Protocol with a view to collect representative and comparable dust exposure data at the level of the industrial minerals sector across Europe. The statistical reliability of the data collected means that it will also be valuable for future epidemiological studies.
The dust monitoring programme was launched in 2000, more than 20 industrial mineral companies have been collecting exposure data following the common protocol since then.

Since 2006, the project is managed by the Institute for Risk Assessment Studies (IRAS), University Utrecht, & Netherlands Expertise Centre for Occupational Respiratory Disorders (NECORD).
Considering data collected up to winter 2008/2009, 17 sampling campaigns took place in 24 companies at 93 different worksites and consisted of 12,647 measurements of respirable dust and 10,075 measurements of respirable quartz.

Results:

Two different measures that describe the probability of exceeding these OELs were reviewed: probability of exceedance and probability of overexposure. Both measures indicated that the probability of exceeding especially the lower OELs for both dust and quartz was relatively high for workers in this sector in several occasions. However, overall downward trends in exposure levels for respirable dust and respirable quartz ranging (from -2 to -26%) per sampling campaign for the majority of job titles were observed in the IMA database over the years 2000-2009.

Prof. H. Kromhout and R. Houba who analyse it consider that the potential of this unique industry-wide exposure database is very high. Considerable improvements in data quality have been achieved during the project, but improvements are still possible, especially with regard to repeated measurements for individual workers within campaigns. The IMA Dust Monitoring Programme Database contains personal measurements of more than 2,000 monitored workers who are assumed to be representative of in total 5,000 workers from industrial minerals production. This unique prospective exposure database will prove to be very valuable in evaluating time trends in exposure to respirable dust and its crystalline silica content and when monitoring the health effects due to exposure to respirable mineral dust among these workers.

Participation from more industrial minerals producers in this IMA-Europe project is always welcome, please contact us for more information.

 

in bulk materials

To quantify the content of fine particles within a bulk product, a working group composed of industry experts within IMA-Europe (the IMA Metrology Working Group) has developed a scientific method called the Size Weighted Relevant Fine Fraction (SWeRF). See article on the SWeRF published in Annals of Occupational Hygiene, 2013.
A procedure has been launched to standardise the method through CEN (the European Committee for Standardisation), see draft standard available here.

This draft standard specifies a method for evaluating the size weighted relevant fine fraction in terms of weight percent, which is a means of expressing the content of fine fraction particles in bulk materials. The method can also be extended to give a means of expressing the content of crystalline silica (fine fraction) particles. The method can be used for comparing the potential health hazard of different bulk products.

SWeRF measurements should not be confused with Dustiness measurements (EN 15051). SWeRF and dustiness methods are complementary. The SWeRF method alone is not a suitable method for risk assessment. SWeRF is not a substitute for workplace exposure measurements.

Dustiness methods measure the propensity of materials to produce airborne dust during certain types of handling and give an indication on how dust concentrations might develop at the workplace. SWeRFCS is an estimation of the content of fine fraction particles of Crystalline Silica in a product and is an unambiguous characterization of the bulk material, taking into account the particle size distribution and the probability of particles, once made airborne, reaching the deep lung (EN 481 curve).

Link to SWeRF calculation xls sheet (2007)

Link to SWeRF calculation xls sheet (2013)

Link to explanatory notes to use the xls sheet

List of labs able to do the SWeRF measurements.


If you wish to implement the SWeRF method and to receive all useful documents and instructions, please contact f.lumen@ima-europe.eu .