Inhalation hazards at work

We rarely consciously perceive the air around us. Nitrogen, oxygen, carbon dioxide and noble gases are invisible and odorless. However, in addition to gases, air can contain any number of other components such as dust, aerosols, vapors, mist and smoke. Dust and particulate matter in particular have become the focus of occupational and environmental health professionals in recent years - and not just because of the car manufacturers' emissions scandals.

Dust: the tinier, the more dangerous

A certain amount of dust is always present in our private and professional lives - with the exception of cleanroom areas. Those who do not suffer from allergies or asthma are often hardly aware of this. However, some dust fractions are highly explosive and companies must protect their employees from the health consequences of inhaling them. Occupational health and safety and hazardous substances legislation refers to inhalation hazards, as opposed to dermal or oral hazards (absorption through the skin or mouth).

• Mineral dusts: Whether granite or basalt, sandstone or limestone, concrete or plaster - rock dust is unavoidably produced during processing. Fine quartz dust is considered particularly dangerous, and the silicosis it causes is recognized as an occupational disease.
• Wood dust: The dust from many hardwoods has been proven to be carcinogenic. These include not only exotic woods such as teak and mahogany, but also many native tree species such as beech, birch, maple and ash.
• Fiber dusts: In addition to asbestos, which was banned in 1990, there are other artificial mineral insulating materials that release tiny but harmful particles during processing, demolition or renovation. The fibrous dusts that are released when cured carbon fiber composites are processed are also suspected to be carcinogenic.
• Welding fumes: If dust particles are produced by a combustion process, this is referred to as smoke. The welding fume particles that occur during many welding processes can cause bronchitis and pulmonary fibrosis.
• Organic dusts: Organic dusts of biological origin often trigger allergies (pollen, mite droppings). Other dusts contain toxins (molds) or are infectious due to airborne pathogens. In addition to the healthcare sector, the sewage and waste industries, agriculture and horticulture as well as the construction industry are also affected, for example by pigeon and mouse droppings during demolition and renovation work.

Even flour or metal can damage the lungs

Dust exposure can also occur at other workplaces. The health risk is easily underestimated in the case of dusts of otherwise unsuspicious substances such as paper dusts, cereal flour dusts that trigger baker's asthma or metal dusts used in additive manufacturing via 3D printing. Regardless of the hazardous properties of a substance (e.g. toxic, irritant, sensitizing or infectious), almost every substance irritates the respiratory tract and eyes as soon as it is finely dispersed in tiny particles.

When the air quality is high, our natural self-cleaning mechanisms such as bronchial mucus or eye blinking cope well with it. However, depending on the type and quantity of dust, as well as the frequency and duration of exposure, dust can become a health hazard. It starts with coughing, sneezing and red eyes and progresses to asthma and bronchitis and even serious illnesses such as metal fume fever and lung cancer.

Proven for protective measures: The STOP principle

The following order of priority applies to measures to protect employees: substitution before technical protection before organizational protection before personal protection.

Substitution means looking for alternatives to dusty products, e.g. mortar in pellet form or ready-to-use tile adhesives that do not need to be mixed first. Or dusty working methods can be replaced by lower-emission working methods such as wet processing.

To the technical Measures include:

• Vacuuming as close as possible to where the dust is generated or released
• Enclosing and encapsulating machines, systems, conveyor technology, etc. into closed systems
• the use of dust extractors, for example on construction sites
• efficient room ventilation with an adequate supply of fresh air
• structural separation, e.g. by means of dust protection walls, foil doors, slatted curtains, etc.

Goal more organizational steps is to organize work in such a way that dust-generating activities are isolated in terms of time and/or space. Employees should not only have the opportunity to wash, shower and change, but also to store work and private clothing separately. Eating, drinking, smoking and inhaling should of course be prohibited.

To the person-related Measures include making employees aware of the consequences of dust exposure and the need for protective measures, as well as instructing them on how to work with low dust levels. If technology and organization do not succeed in minimizing inhalation exposure to an acceptable level, the employer must provide respiratory protection PPE. The MAK values published by Suva are relevant as limit values for the concentration at the workplace.

Protective equipment for the respiratory tract

Analogous to head protection, eye protection, hand protection, etc., respiratory protection should actually be called lung protection. This is because it is not the breath that is protected, but the airways or lungs. Simple respiratory protection begins with disposable fine dust masks, which became known as particle-filtering half masks with the FFP (filtering face piece) code due to the corona pandemic. FFP3 masks offer the highest level of protection. Half masks are also available in reusable form with replaceable particle filters. Respiratory masks are used for many typical dust hazards such as rock dust in construction, wood dust in carpentry or dust from grinding work. However, at the latest when hazardous gases or vapors occur in addition to dust - for example in some welding processes - the protection provided by such dust masks is not sufficient.

Respiratory protective devices, which are divided into filtering devices and insulating devices, are much more complex. Filtering devices are available with and without a blower, as particle or gas filters or in combination. Isolating devices work independently of the ambient atmosphere, as compressed air breathing apparatus or as - not freely portable - hose devices with fresh air or compressed air. This blower and compressed air respiratory protection uses different filter systems whose service life and filter change intervals must be taken into account. Their specific protective effects - for example against organic gases, mercury vapors or particles - are color-coded according to international standards.

Finding the optimum technical solution for the specific need for respiratory protection on site is not easy; thorough advice, e.g. from a specialist retailer, is advisable. It should not be overlooked that wearing heavy respiratory protection places a strain on the body and is therefore not a permanent measure.

When procuring PPE, it should be borne in mind that additional protective functions - over and above inhalation hazards - are often necessary when exposed to dust. This is because dust also irritates the eyes and skin, and protective goggles and gloves prevent this. Depending on the working environment, safety shoes, helmets, hearing protection, etc. may also be required. Care must always be taken to ensure that the individual PPE components do not interfere with each other's effectiveness. If, for example, respiratory masks are worn at the same time as safety goggles, this combination must be compatible.

Friedhelm Kring is a freelance author specializing in occupational safety.