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Dust

Viimati uuendatud: 11.10.2019


Dust

Dust are very small particles that enter and stay floating in the air, for a shorter or longer period of time. In essence, dust floating in the air is an aerosol – particles of solid and/or liquid substances in the air. Usually, aerosol particles are invisible to the bare eye; they are microscopic. The smallest solid particles in air are called particles. Their diameter is usually under 0.1 mm.

From the perspective of health it does not matter whether air contains solid or liquid particles – other properties of the substances are significant instead.

Even though dust and particles are usually seen as solid substances, the solid particles only appear in the air together with liquid drops – meaning, in the form of an aerosol.

One interesting example of dust is smoke. It consists of both solid and liquid particles that are bound to gaseous substances that form in burning.

Daily, particles visible to the eye are treated as dust. Particles become visible when they stick together and achieve such measures that the eye can see. Therefore, if the dust mass is big enough, it is also visible.

Dust is mostly caused by the decay of materials (most commonly, textile and paper). Working environment has several sources for particles: timber industry, metal sanding, powder painting; but also offices (paper dust) and bakeries (flour dust).

Health Effects

Dust particles floating in the air mostly affect the airways, but dust also irritates the eyes (primarily, the conjunctiva of the eyes) and skin.

Eyes

Dust can clog the tear duct and cause inflammation. Inflammation could also be caused by the chemical or allergenic characteristics of the dust.

Skin

Dust particles stick to skin secretion (sweat and fat), enabling to stick on the skin. This may block skin glands and hairs, resulting in their inflammation. The effect of dust particles depends on their length of contact with skin.

Respiratory Tract

The most basic irritating effect is visible on the mucous membrane of the upper respiratory tract, which can result in chronic dust bronchitis. One of the most characteristic symptoms is the constant need to cough and moderate sputum.

If dust penetrates deeper into the respiratory tract, an irreversible process called pneumoconiosis may begin. The illness develops slowly and presupposes extended work in dusty conditions. The greatest problem of the illness is that if the organism cannot excrete the dust particles, connective tissue is grown around them. Growing connective tissue in lung takes place on the account of lung tissue and the lungs’ gas exchange ability decreases. The process is irreversible as the connective tissue will never function as the lung tissue.

Allergenic dust may trigger bronchial asthma, which generally rules out continuing the same work.

Also other illnesses related to the hypersensitivity reaction are described which occur due to the effect of dust; for example, lung damage byssinosis caused by cotton dust, also known as bronchospastic bronchiolitis. In the case of the so-called farmer’s lung or bird-breeder’s lung, the disease is caused by mould spreading on decaying hay. The so-called cheese-maker’s lung is an extra sensitivity reaction originated against the mould used in making cheese. All the aforementioned are cases of allergic pneumonitis.

Prevention

Several methods can be applied to decrease dust. The most effective is, of course, to remove the source of dust. It is possible to isolate the employee from the dusty environment by building a dustproof booth for managing the device or work process. One option of insulation is to use efficient respiratory protective equipment. The choice of the latter must be based on the knowledge what is the character of these substances and how big are the particles that form the aerosol floating in the air.

Do not forget to protect the eyes and skin. Dusty works require tight-fitting glasses. Clothes from a dense material can be used to protect the skin, but a more comfortable, and usually also sufficient, option is to properly clean the skin (shower after the workday).

In some cases, it is possible to limit the dusty activities by replacing a dry process with a wet one. But the aerosol particles arising in this case could also endanger the employees through air – so, this solution should be used in parallel with the dust avoidance (decreasing) option in the working environment.

Sufficiently frequent and practical cleaning also helps in the case of dusty works, but a vacuum cleaner should be chosen over brushing dust together. As the dust concentration in the air increases during the cleaning, a respiratory protection must certainly be worn during the cleaning.

The entire dust marginal rate in the workplace air is 10 mg/m3, the same norm also applies to the dust of some food products. But it must still be kept in mind that the upper allowed limit of fine dust (i.e. all the share of the dust that reaches the air, or particles smaller than 2.5 µm (PM 2.5)) is indeed only 5 mg/m3.

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