Occupational health and safety (OHS) standards in Germany are based on the federal “Chemicals Act” (gesetzliche Grundlage “Chemikaliengesetz”) and on a federal government rule, which addresses various issues related to dangerous substances (“Gefahrstoffverordnung”).
Exposure limits in the workplace are usually proposed by a special scientific board of DFG (Deutsche Forschungsgemeinschaft). Next, the proposed limits are discussed with all stakeholders within the MAK-Kommission. The final limits are established by the German Ministry of Labor (Bundesministerium für Arbeit - BMA) through TRGS regulations (technische Regeln für Gefahrstoffe). The TRGS documents are published in the “Bundesarbeitsblatt”.
The occupational health and safety standards are enforced by occupational insurance organizations called Berufsgenossenschaften. There are 35 Berufsgenossenschaften for different areas in the industry (e.g. Tiefbauberufsgenossenschaft—TBG responsible for construction). These insurance organizations perform various functions, such as air quality measurements at the site, to ensure compliance with the regulations.
All Berufsgenossenschaften have a common institution BIA (Berufsgenossenschaftliches Institut für Arbeitssicherheit) which performs many functions, including regular publication of all OHS limits and rules.
The above organization extends to all occupational health environments with the exception of coal mining. Until the year 2002 the OHS matters in the coal mining are the responsibility of state (Land) mining authorities called Oberbergbehörde.
There are two types of exposure limits:
- MAK (Maximale Arbeitsplatzkonzentration) is the maximum concentration of a substance in the ambient air in the workplace which has no adverse effect on the workers' health.
- TRK (Technische Richtkonzentration) is the concentration of a substance in the ambient air in the workplace that can be achieved using technically available measures.
Once established, both types of limits are legally binding and have to be observed in the workplace.
The following table summarizes the exposure limits for the major diesel exhaust pollutants (Technische Regeln für Gefahrstoffe TRGS 900).
|Diesel Particulates (EC), tunneling & non-coal mining||-||0.3a||4|
|Diesel Particulates (EC), other applications||-||0.1a||-|
* - All values in the table have to be met as work-shift time weighted averages. The following short term exposure categories apply: 1 - ceiling value, not to be exceeded at any point in time; 4 - ceiling value = 4 x the limit value
a - TRK limit
The diesel particulate emissions (DME - Dieselmotorenemissionen) are defined as elemental carbon (EC) and are limited in size to about 5 µm (EN 481). This definition is different, and more precise, than the dilution tunnel particulate matter determination, which is used for the tailpipe engine emission measurement. Contrary to the CVS dilution tunnel sampling, the German occupational health definition excludes such artifacts as water, sulfuric acid, or hydrocarbons. These substances produce condensates under the artificial conditions in the dilution tunnel. German authorities concluded that the condensates should not be included in the measured particulate mass, due to the different health impact of condensates and insoluble carbon particles. The gaseous pollutants are regulated separately and measured in the gas phase.
Diesel particulates are classified as “probably carcinogenic for humans”. This classification requires that the “best available technology” (BAT) is used for emission reduction.
Diesel Engine Regulations
Specific rules pertaining to the use of diesel engines in occupational health environments were first introduced on 30 April 1993 (TRGS 554). These regulations introduced a general TRK exposure limit for diesel particulates of 0.2 mg/m3 and a limit of 0.6 mg/m3 for underground non-coal mines and tunneling. The particulates were defined as total carbon (EC + OC) and determined by a coulometric analysis.
The regulation was modified in 1996. The TRK limits for diesel particulates in the workplace and in mining/tunneling were lowered to 0.1 and 0.3 mg/m3, respectively (compare Table 1). The definition of diesel particulates was changed to elemental carbon (EC). The measurement involves a two stage thermal analysis with coulometric identification [Method 2 according to ZH 1/120.44 /Oct. 1990 (BIA) and VDI standard 2465].
Coal mines are exempted from the above limits due to the difficulties in differentiating between diesel particulates and coal dust.
The TRGS 554 sets several additional requirements that have to be observed whenever diesel engines are operated in buildings, underground, or other enclosed areas. These additional provisions have to be also observed in coal mines. The following are some of the requirements:
- Diesel engines that are entirely or partially operated in enclosed spaces or underground must be equipped with particulate traps, provided such traps are technically feasible.
- The particulate traps must achieve at least 70% total gravimetric filtration rate, as measured on the UBA (Umwelt Bundesamt) engine test cycle.
- Diesel engines must undergo periodic measurements of smoke number and CO level.
It should be emphasized that the diesel traps are required in addition to the TRK exposure limit. The filtration efficiency of most traps that are used is better than the required 70%. As a result, according to the measurements of TBG, the average particulate exposure in tunnel sites is now well below 0.1 mg/m3, a much lower value than the TRK of 0.3 mg/m3.
Future Directions: Fine Particles
The DFG/MAK-Kommission in its recent paper “Ultrafeine Teilchen, deren Agglomerate und Aggregate” (MAK, 27.Lieferung 1998) has addressed the importance of fine particles for human health. The following issues have been raised:
- Ultrafine, insoluble particles are characterized by high mobility and are likely to present much higher health risk than the bigger particles.
- The paper defines a particle class of 5-10 to 200 nm aerodynamic diameter, and calls for measurement of number concentrations (up to 100 000 000 particles/cm3).
- The number concentration, and not the mass concentration, is believed to affect human health. Surface concentration may be also important.
It is expected that future regulations will include limits for the number concentrations of diesel particulates, in addition, or in place, of the mass concentrations that are used today.