• Dust consists of solid particles carried by air currents. It is also defined as solids carried by air from a place without chemical or physical change.
  • Dust is formed from fracturing or crushing processes such as grinding, crushing, and impact.
  • Dust is generated by manufacturing, domestic, and industrial activities. Construction, agriculture, and mining are among the industries that contribute the most to increasing dust levels in the atmosphere.
  • These activities generate varying amounts of dust, depending on the physical characteristics of the material and how it is processed.
  • Dust is generally micrometers in size (known as microns).


Examples of the above dust are:
  • Sand (inorganic, non-metallic, silica-bearing, free silica, crystalline)
  • Cotton or cotton (organic, natural, vegetal)
  • Beryllium (inorganic, metal)
Alternatively, classified dust in terms of its health effects. Dust is identified as:
  • Innocuous - iron oxide, limestone (may also be considered nuisance dust).
  • Acute respiratory hazard - cadmium fume.
  • Chronic respiratory hazard - airborne asbestos fibers.
  • Sensitive people - lots of wood dust.

Fibrogenic dust, such as free crystalline silica (FCS) or asbestos, is biologically toxic. and, if deposited in the lungs, can form scar tissue and impair the ability of the lungs to function properly.

Nuisance dust can be defined as dust containing less than 1% quarts. Because it contains little silica, nuisance dust has a long history of adverse effects on the lungs. Reactions that occur due to nuisance dust have the potential to become acute illnesses. However, too much concentration of dust in the workplace can reduce ability and cause unpleasant effects on the eyes and nasal passages. And it can cause injury to the skin and mucous membranes from chemical or physical action.


Particle size is very important in determining which particulates will settle in the lungs. Larger particles will settle in the bronchi and bronchioles and will not tend to penetrate into the smaller airways commonly found in the alveolar region. These are called inspirable particles. The smaller particles that can penetrate the gas exchange in the lungs, the alveolus, are called respirable particles.

  • Inspirable Particulates: Only part of the total amount of dust present in the worker's breathing zone is inhaled. This portion is referred to as the `inspirable fraction' of dust. and is governed by exhalation in the nose and mouth area, as well as airflow around the head. 'Inspirable' dust, as measured by the method described in AS3640-89, is derived from the inspirable and `inspirable mass fraction' as defined by ISO or from the inspirable particulate mass fraction previously used by ACGIH. Some authorities, such as ACGIH, now use the term inspirable dust fraction. `inhalable' or `total inhalable'.
  • Inhalation particles: dust particles have a cut-off point of 50% of 4 microns (ACGIH). Or 5 microns (BMRC). These particles are harmful when deposited in the respiratory region of the lungs.

The size of a particle is expressed as its "equivalent" or "aerodynamic" diameter. Equal to the spherical particles of the existing particle density have the same falling speed in the air. Among the inhaled particles, those with particles larger than 20 microns will reach the upper part of the respiratory system.

Inhaled particles that have 50% of 100 microns and include large and small particles. Particles with a size of 7–20 microns will penetrate the bronchioles and inhoulus, while large Particles between 0.5 and 7 microns will be inhaled. Particles with smaller sizes will not be stored because before the particles are stored, they will first be blown back.

From a health point of view, dust is classified according to size into three That is:

1. Respirable dust

The average diameter of this dust is 4 microns (ACGIH) or 5 microns (BMRC).

2. Inhalable dust

The EPA explains that inhalable dust is respirable dust that enters the body, but is trapped in the nose, throat, and upper respiratory tract. The average size of this dust is 10 microns.

3. Total dust

Total dust in an air stream, regardless of size and composition.


Excessive dust emissions can cause health and industrial problems.

1. Health hazards

  • Danger of respiratory disease.
  • Eye, ear, nose and throat irritation.
  • Skin irritation.
2. Dust risks from explosions and fires.
3. Equipment malfunction.
4. Impaired visibility.
5. A bad smell.
6. Problems in public relations.

The biggest concern is the health hazard for workers who excessively breathe in hazardous air. To evaluate health and safety in the work environment, the American Conference of Governmental Industrial Hygienists (ACGIH) has issued standards called threshold values. These values are used as a guide in the evaluation of health hazards. The threshold value is the minimum amount that workers inhale dust in 8 hours of work without being affected.


Not all dust is harmful to health, influencing factors include:

1. Dust composition

  • Chemistry.
  • Mineralogy.
2. Dust concentration
  • By weight: milligrams of dust in a cubic meter of air.
  • Quantity: millions of particles per cubic foot of air.
3. Particle size and shape
  • Distribution of particle size over the range of respirable particles.
  • Fiber or spiral.
4. Time exposed

Long-term excessive exposure to or inhalation of dust is harmful and can result in a respiratory disease called pneumoconiosis. The disease is caused by the buildup of minerals. particles or metal dust in the lungs and the resulting reaction to inhaled dust. Pneumoconiosis is the common name for a number of dust-related lung diseases.

The duration of exposure may be general, i.e., minutes or hours, but usually not more. than a day or two, whereas the duration of exposure may be measured in months or years. over the course of working at the site.

Some airborne particulates may cause acute toxic effects after inhalation exposure. e.g., beryllium, or metal fumes, fever may occur after exposure to metal fumes. Other Particulates may cause toxic effects after a longer period of time, perhaps several days. to weeks, for example, manganese. Such exposures can be called subchronic. Chronic lung Conditions, such as pneumoconiosis or mesothelioma, may result from exposure to silica dust.

Some types of pneumoconiosis are:

  • Silicosis: Silicosis is a form of pneumoconiosis caused by quartz dust and silica dust. The condition of the lungs is characterized by nodular fibrosis (scarring of the lung tissue), resulting in shortness of breath.
  • Black lung is a form of pneumoconiosis that results from coal dust particles. accumulating in the lungs and darkening the tissue. The disease is progressive. Although the disease is commonly known as black lung, its official name is coal. worker's.
  • Pneumoconiosis (CWP). Asbestosis: Asbestosis is a form of pneumoconiosis caused by asbestos fibers.
Airborne Dust Concentration

The concentration of dust that hits a person has an impact on that person's health. It is measured within the worker's breathing zone, which is an imaginary line of about 30 cm, the line is in front of the face and measured from the midpoint of the imaginary line connecting the ears.

Measurement of dust concentration

  • Airborne dust concentration is usually assessed by collecting dust on a filter. A known volume of air is drawn through the filter, which is then reweighed. The weight difference is the mass of the dust, usually in milligrams (mg) or micrograms (mg), and the volume is expressed as cubic meters of air (m3). For example, the overall concentration of dust in the air is measured in mg/m3 or m g/m3.
  • When measuring, airborne dust concentrations can be assessed against set standards. In Australia, these are determined by the National Occupation Safety and Health Commission (Worksafe Australia) and are published as Occupational Exposure Standards for Airborne Contaminants and accompanied by their interpretation Guidance Notes. In the United States, the American Conference of Governmental Health in Industry (ACGIH) publishes threshold values (TLVs) annually, while in the UK, the Health and Safety Executive (HSE) publishes open working limits (OELs) and occupational exposure standards (OESs).
How to control dust?

Dust control is the study of how to reduce harmful dust emissions by applying sound engineering principles. Well-designed, maintained, and operated dust control systems can reduce dust emissions and, thereby, reduce workers' exposure to hazardous dust. Dust control Systems can also reduce equipment wear, maintenance, and downtime; increase visibility; and improve employee morale and productivity.

Reduced exposure to dust can be achieved with three main steps:

  1. Prevention.
  2. Control System.
  3. Dilution or isolation.

1. Prevention

The saying "prevention is better than cure" can also be applied to dust control. While total dust prevention in bulk material handling operations is an impossible task, if designed properly, bulk material handling components can play an important role in reducing dust generation, emissions, and dispersion.

2. Control System

After taking all necessary precautions, one or more of the following methods can control any remaining dust in the workplace:

  • Dust collection system.
  • Wet dust capture system, and
  • captures dust in the air through water spray.
Dust collection system

Dust collection system with industrial ventilation principles to capture airborne dust from the source. This captured dust is then transported to the dust collector, which then cleans the dusty air.

Wet dust suppression system

Wet dust suppression systems use a liquid (usually water) to wet the material so that it has a lower tendency to produce dust. Keeping the material wet makes it difficult to generate dust.

Dust Captured in the Airflow

This technique captures airborne dust by spraying fine droplets of water into the dust. cloud. The water droplets and dust particles collide and form clumps. Once these clumps become too heavy to remain in the air, the dust falls out.


This technique reduces dust concentrations by diluting contaminated air with fresh, uncontaminated air. In general, ventilation dilution is not very effective for health hazard control. However, it can be applied in situations where operations or processes prohibit other dust control measures.


Isolation is another way to protect workers from exposure to hazardous dust. In this technique, workers are placed in a shroud and provided with clean, filtered air.


The purpose of a respirator is to prevent harmful inhalation of airborne substances and/or lack of oxygen. Functionally, respirators are designed as a container that covers the nose and mouth or the entire face or head.


It is designed to form a seal with the wearer's face. Types: quarter mask, half mask, and full face cover. The quarter mask covers the nose and mouth, where the lower sealing surface is located between the chin and mouth. The half mask covers the nose and mouth and fits under the chin. The full face cover covers the entire face, from under the chin to the hairline.


Has a breathing inlet cover designed to form a partial seal with the face. These include loose facepieces, as well as hoods, helmets, blouses, or full garments, all of which cover the head completely. The best-known loose-fitting respirator is the air-supplied hood used by abrasive blasters. The hood covers the head, neck, and upper torso and usually includes a neck cuff. A compressor pushes water towards the tent through a hose. Because the hole is not tight fitting, it is important that sufficient air be provided to maintain a slight positive pressure inside the tent relative to the environment immediately outside the tent. In this way, outward airflow from the respirator will prevent contaminants from entering the tent.


It is the result of a lack of oxygen or the inhalation of air contaminated with toxins, vapours, gases, smoke, or mist. Proper selection and use of respirators depends on a preliminary determination of the concentration of the hazard or hazards present in the workplace.

Air hazards are generally in the following basic categories: Dust. Particles are formed or generated from solid organic or inorganic materials by reducing their size through mechanical processes such as crushing, grinding, drilling, abrading, or blasting.

  • Smoke. Particles form when vaporised solids, such as metals, condense in cold air. Frequently, a chemical reaction like oxidation occurs along with this physical change. Examples are lead oxide fumes from smelting and iron oxide fumes from arcwelding. A fume can also form when materials such as magnesium metal are burned or when gas welding or cutting is performed on galvanised metal.
  • Fog is formed when a finely divided liquid is suspended in the air. An airline of suspended liquid droplets may be generated by condensation, which is gaseous to a liquid state, or by breaking up a liquid into dispersed states, such as by splashing, foaming, or atomization. Examples are oil mist produced during cutting and grinding operations, acid mist from electroplating, acid or alkali mist from painting operations, paint spray mist from spraying operations, and condensation of water vapour to form mist or rain.
  • A gas is a formless liquid that occupies a space or enclosure and which can be converted to a liquid or solid state only by the combined effects of increased pressure and decreased temperature. Examples are welding gases such as acetylene, nitrogen, helium, and argon, and carbon monoxide produced from the operation of internal combustion engines. Another example is hydrogen sulphide, which is formed wherever there is decomposition of sulphur-containing materials under reducing conditions.
  • Vapours are the gaseous form of substances that are normally in the solid or liquid state at room temperature and pressure. Evaporation from a substance causes it to form. liquid or solid, and can be found where part cleaning and painting takes place and where solvents are used.
  • Smoke consists of carbon or soot particles resulting from the incomplete combustion of carbonaceous materials such as coal or oil. Smoke generally contains droplets as well as dry particles.


Respirators provide protection either by removing impurities from the air before they are inhaled or by providing an independent source of inhaled air. There are two main groups of respirators:

  • Air-purifying respirators (devices that remove contaminants from the air).
  • particulate matter removal.
  • vapor and gas removal, and combinations.
  • Atmosphere-supplying respirators (tools that provide clean breathing air from uncontaminated sources). Each class of respirator may have tight-fitting and loose-fitting facepieces.
  • Elements that remove particles are called filters, while vapour and gas-removing elements are called either chemical cartridges or canisters.
  • Filters and canisters/cartridges are functional parts of respirator air purifiers, and they can generally be removed and replaced once their effective life has ended.
  • The exemption would screen for facepiece respirators (commonly referred to as "disposable respirators," "dust masks," or "single-use respirators"), which cannot be cleaned, disinfected, or resupplied with unused filters after use.


An adequate fit is required for respirators to be effective. Not all workers can wear respirators.

  • Individuals with impaired lung function due to asthma or emphysema. For example, you may be physically unable to wear a respirator.
  • Individuals who cannot get a suitable facepiece, including those whose beards or sideburns interfere with the facepiece seal, will not be able to wear a tight-fitting respirator.
  • In addition to these issues, respirators can also be associated with communication problems, vision problems, fatigue, and reduced work efficiency. In principle, respirators are usually capable of providing adequate protection.

However, problems with fitting, choosing, and using them too often make them less useful in real life. These issues make it impossible to guarantee consistent and reliable protection, no matter how well the respirator works in theory.


The following information must be taken into account:

  • The nature of the hazard and the physical and chemical properties of the contaminant air.
  • Contaminant concentration.
  • Relevant permissible exposure limits or other limits.
  • The nature of the operation or work process.
  • The period of time the respirator is worn.
  • Work activities and physical/psychological stress.
  • Fit testing; and
  • Physical characteristics, functional abilities and limitations of respirators.

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