Dust is very small particles that are released into the air and remain floating there for a short or long time. Dust suspended in the air is in itself an aerosol – solid and/or liquid particles that have been released into the air. Usually aerosol particles are not visible to the naked eye, as they are microscopic. The term ‘particle’ usually refers to the smallest solid components in the air. They are usually less than 0.1 mm in diameter.
From the point of view of human health, it is not important whether solid or liquid particles are present in the air, but other properties of the substance are important.
Although dust, as well as particles, refers primarily to solids, in reality, solid particles are still present in the air together with liquid droplets, i.e. in the form of an aerosol.
Another curious example of dust is smoke. It consists of both solid and liquid particles associated with gaseous substances from combustion.
In everyday life, dust is the particles that are visible to the naked eye. The particles become visible to the eye when they adhere to each other to a size that the eye can distinguish. Thus, if the dust mass is large enough, it is also visible.
Dust is mainly caused by the decomposition of materials (more often textiles and paper). There are many sources of particles in the working environment: the timber industry, metal grinding, powder coating, but also offices (such as paper dust) and the bakery industry (flour dust).
Dust particles in the air mainly affect the respiratory tract, but dust also irritates the eyes (especially the conjunctiva) and the skin.
Dust can clog the lacrimal gland or tear duct, which can cause inflammation. Inflammation can also be caused by the chemical or allergenic properties of dust.
Dust particles combine with skin secretions, sweat and sebum, allowing them to adhere strongly to the skin surface. This in turn can clog the skin glands and hair follicles, which can also lead to inflammation. The effect of dust particles also depends on how long they have been in contact with the skin.
The mildest irritant effect is on the mucous membrane of the upper respiratory tract, which may result in dust-induced chronic bronchitis. One of the most obvious outcomes is the need for frequent coughing and moderate sputum production.
If dust enters the lower respiratory tract, an irreversible process can develop – pneumoconiosis. The development of the disease is slow and requires long-term work in dusty conditions. The biggest problem with the disease is that when the body is unable to excrete dust particles, it surrounds them with connective tissue. In the lungs, connective tissue grows at the expense of lung tissue and the ability of the lungs to exchange gas decreases. The process is irreversible because connective tissue will never begin to perform the function of lung tissue.
Allergenic dust can cause bronchial asthma, which usually precludes further work in the same field.
There are several different techniques you can use to reduce dust. Removing the dust source is certainly the most effective. It is possible to isolate the worker from a dusty environment by building a dust-tight cab to control a device/work process. One way to isolate is to use effective respiratory protection. The choice of the latter must presuppose knowledge of the nature of the substances and how large are the particles that form an aerosol suspended in air.
Eye and skin protection must not be forgotten either. For dusty work, it is necessary to use tight-fitting goggles. It is possible to use dense-textured clothing to protect the skin, but it is more convenient and usually sufficient to take good care of the cleanliness of the skin (shower at the end of the working day).
In some cases, it is possible to limit dusty activities by replacing the dry process with a wet one. As aerosol particles in this case can also endanger people through the air, the technique should be combined with local exhaust ventilation, which is often one of the most effective ways to prevent (reduce) dust in the working environment.
Sufficiently frequent and efficient cleaning also helps with dusty work; when cleaning, a vacuum cleaner should be preferred to sweeping dust with a brush. As dust levels increase during cleaning, it is necessary to wear respiratory protection.
The limit value for total dust in the air of the working environment is 10 mg/m 3, the same limit has been established for dust of some individual substances. However, it must be borne in mind that the maximum permissible limit for fine dust (i.e. all the dust reaching the lungs, or particles with a size of less than 2.5 µm (PM 2.5)) is only 5 mg/m 3.