The Technical Rules for Hazardous Substances - TRGS 900 regulates the permissible exposure at the workplace for a large number of hazardous substances. Among other things, a general dust limit value is also specified. This applies to insoluble and poorly soluble substances that are covered elsewhere in TRGS 900. The general dust limit value is also implemented as an upper limit value in Dustlight.
The general limit value for dust
The specified occupational exposure limit values (OELs) refer to the shift average, i.e. the average concentration over an 8-hour working day. This value therefore indicates the concentration of a substance up to which acute or chronic harmful effects on health are generally not to be expected. This also applies to a daily exposure of eight hours on five days per week during the working life.
| Respirable fraction (respirable dust) | 1 250 μg/m3 |
| Inhalable fraction (E Dust) | 10 000 μg/m3 |
Limit values for Dustlight:
The warning LEDs on the Dustlight refer to the respirable dust.
- The upper limit value, i.e. when the light switches to red, is 1250 μm/m ³ at the level of the general dust limit value. These threshold values can be adapted to your requirements via our app.
- The lower limit value for when the light switches to yellow is 10% of the upper limit value, i.e. 125 μm/m³. This corresponds to an evaluation index of 0.1, see section "Interpretation of results".
- With such a stratified mean value, it can be assumed with a sufficiently high probability that the limit value will not be exceeded in the future, even under worse boundary conditions.
Exposure peaks and short-term values
Occupational exposure limit values are mean values, which means that they may be exceeded for short periods. Such exceedances are limited in their level, frequency and duration.
These exceedances are defined as short-term value phases over a period of 15 minutes, whereby the average value over this period is considered. There is no maximum permissible instantaneous value for the general dust limit value.
For E dust, a maximum permissible exceedance factor of 2 is specified, for respirable dust a factor of 8 applies. Exceedances longer than 15 minutes are permissible if the product of the exceedance factor and exceedance duration is complied with. For example, the exceedance factor 8 applies to the 15-minute reference period for respirable dust, so an exceedance by a factor of 4 in a 30-minute period is also permissible.
Over the course of the day, the mean shift value must be observed in all cases. In addition, at least one hour must elapse between two short-term value phases.
Concentration-related conversion for respirable dust
For respirable dust, a particle density of 2.5 g/cm ³ is assumed. If the substances present and their density are known, the limit value may also be converted according to the actual density.
Risk assessment - The findings according to TRGS 402
Simply complying with a limit value in a single measurement is not sufficient for the statement "protective measures sufficient" in the context of a risk assessment. If necessary, further justification must be provided. TRGS 402 describes the assessment principles for inhalation exposure. First, the measured dust exposure is converted into an evaluation index (BI) in order to obtain a standardized evaluation basis. Depending on the level of the BI, it can then be assessed whether further justification is required.
BI = shift average / limit value
BI > 1 - protective measures not sufficient -> exposure-reducing measures must be taken immediately.
BI <=1 Maßnahmen ausreichend, wenn zusätzlich begründet werden kann, dass auch zukünftig die Grenzwerte eingehalten werden. Hierfür gibt es 5 Möglichkeiten:
1 - worst case
2 - Stable boundary conditions in the long term
3 - Continuous monitoring
4 - Ongoing effectiveness monitoring
5 - Experience of comparable workplaces
BI <= 0,25 bei Messungen während drei verschiedenen Schichten – Maßnahmen ausreichend BI <= 0,1 während einer Schicht – Maßnahmen ausreichend gestellt werden, dass alle Parameter, die Einfluss auf das Ausmaß der inhalativen Exposition haben, bekannt sind.
Ideally, the measurement takes place in the worst case of these boundary conditions, so that higher exposures can be ruled out in the future.
Protective measures when handling hazardous substances
The STOP principle describes the order of priority of the protective measures:
Substitution: Can hazardous substances be replaced?
Technical protective measures: technical ventilation, extraction, spatial separation, etc.
Organizational measures: Reduce residual hazards, e.g. through safety instruction, adaptation of work procedures, etc.
Personal measures: e.g. protective clothing, safety goggles or filter masks.
Ongoing effectiveness review of the protective measures
Dustlight is ideal for checking the effectiveness of safety equipment with regard to correct extraction. According to GefStoffV Annex 2 Number 2.3 (7), technical protective measures such as dust separators, collection systems and systems for measuring precipitation must be checked annually. Although a complete repetition of existing risk assessments is not required by law, the regular inspection of these protective measures is essential. Dustlight provides a precise and efficient method of ensuring that these requirements are met.
FAQs
Who is allowed to carry out dust measurements?
The determination, monitoring and documentation as part of the risk assessment in accordance with the Hazardous Substances Ordinance (GefStoffV) is generally the responsibility of the employer. If the company is unable to carry out the measurement itself for technical or personnel reasons, external bodies can also be commissioned. Such bodies can be accredited by the Deutsche Akkreditierungsstelle GmbH (DAkkS) if they meet the quality requirements. There are also state measuring bodies and those of the accident insurance institutions.
What is TRGS 900?
The Technical Rules for Hazardous Substances, or the technical regulations for the Hazardous Substances Ordinance, are drawn up by the Committee for Hazardous Substances (AGS). TRGS 900 contains the occupational exposure limit values that are used as part of a risk assessment.
How is the occupational exposure limit value (OEL) determined?
The occupational exposure limit values (OELs) can be found in TRGS 900. The Committee for Hazardous Substances (AGS) sets these according to the "state of the art, occupational medicine and occupational hygiene as well as other established scientific knowledge".
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