Hazardous substances
What is considered as hazardous substances?
Hazardous substances are chemical or artificial, and naturally produced substances or mixtures. Some are harmful to humans only after reactions with other substances and have characteristics such as toxic, irritating or corrosive. Nonetheless, dusts of harmless substances can be dangerous as well. They consist of tiny particles that can be inhaled or absorbed through skin contact. For example, welding technology releases hazardous substances that appear in particulate or gaseous forms. The chemical composition and concentration of emissions such as welding fumes are free from the materials and the methods used. Particles released may be A-dust and thus respirable or E-dust which may pollute the upper airways. The limit values are 1.25 mg / m³ for a dust and 10 mg / m³ for E dust. Airborne swirling can cause explosive dust-air mixtures with a very low explosive limit of 15 mg / m³, even if the dust is deposited at a height of 1 mm.
Hazardous substances in welding work
Examples of hazardous substances are complex mineral oil, coal and natural gas derivatives (former EC Directive 67/548 / EEC, since June 2015 Globally harmonized system for classification and labeling of chemicals (short GHS)), so-called CMR substances according to the Institute for Occupational Safety and Health (IFA = German “Institut für Arbeitsschutz”)) and explosive or highly flammable substances. According to GefStoffV §10 par. 5 (German Ordinance on Hazardous Substances), extracted air with CMR substances of category 1A and 1B are not allowed to be released into the air. The IARC, a specialized department of the WHO, classifies substances with regard to the hazard potential to humans. In Group 1 are carcinogenic substances such as welding fume, tobacco, UV radiation and chromium IV components.
CMR particles =
Carcinogenic, mutagenic, toxic to reproduction
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Effect on people |
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Category 1A |
Is proven |
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Category 1B |
Is very likely because it is proven on animals |
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Category 2 |
Is to assume |
Safety is the top priority
The employer must respect the safety of his employees at work and point out any potential danger to them. Regular cleaning and ventilation is essential, especially when dealing with CMR substances. Most technical rules and standards assign the following technical protection measures in such processes:- Avoiding
- extract directly at point of emission
- measuring ventilation
- having personal protective equipment
Tested air filtration system
When separating non-explosive hazardous substances in circulation operation, the operator has to carry out the extraction system’s separation degree while commissioning by means of an officially tested procedure. If no separation degree has been adequately proven, the filtered air must be discharged to the outside. The emission rate has to be tested once a year, as well as before commissioning and when major changes are made to the system. In addition, the systems must be maintained once a year according to the manufacturer’s instructions. Alternatively to the separation rate determination at commissioning, the operator can use a type-tested filter and extraction system with a confirmed separation rate, e.g. according to DIN 60335-2-69 AA, or a confirmed separation rate according to W3. The W3 welding smoke approval is an officially tested degree of separation of the filter classes and is necessary when depositing hazardous substances. A certification of the entire system is not mandatory, but merely serves as a supplement to the legal guidelines. TBH filtration and extraction systems have a degree of filtration according to W3 confirmed by the IFA and they can be used to extract CMR substances as well. The systems are suitable for automation technology because they are equipped with an H13 filter, a signal on the display, a volume flow meter, a signal unit and an interface that evaluates errors.When dealing with hazardous substances, employees have to observe the following rules:
- Observe safety regulations (§ 7 par. 4 German Ordinance on Hazardous Substances)
- Do not eat if there are hazardous substances in the room.
- Wash hands and, if necessary, change clothes after leaving the work area.
- Do not fill hazardous substances in food containers.
- Do not try to identify a hazardous substance on your own.
- Train employees concerning potential risks.
- Pay attention to the correct labeling of containers with hazardous substances.
- Use substitutions for hazardous substances if possible.
- Comply with occupational exposure limits
- Detection of the emissions as complete as possible, directly at the point of origin with a suitable extraction and filter device
- Failure of the ventilation device must be recognizable to all (TRGS 500)
- Use emission-free or low-hazardous processes and additional materials (§ 7 par. 4 German Ordinance on Hazardous Substances)
- Clean transition zones and working areas with officially recognized vacuum cleaners of dust class H (DIN EN 60335-2-69 [15], TRGS 517)
- Connect lead-resistant workstations to stationary extraction systems and provide mobile suction systems (TRGS 505)
Since December 2010, a globally uniform classification and labeling of chemicals has become valid and has to be observed.
Label example
- Product name
- Hazard symbol
- Name of the dangerous contents
- Hazard warnings
- Security advices
- Producing company with postal address and telephone number
