Characteristics of Dust Particles in Gaseous Medium Quiz

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Questions and Answers

What determines the harmfulness of dust?

Composition, concentration, size, exposure time, and individual susceptibility (correct)

Exposure to sunlight

Particle size and shape

Humidity levels in the atmosphere

Which type of dust is harmful to the lower respiratory system?

Fibrogenic Dusts (correct)

Carcinogenic Dust

Radioactive Dust

Toxic Dust

Which type of dust harms the upper respiratory system?

Radioactive Dust

Toxic Dust

Explosive Dust

Carcinogenic Dust (correct)

What is the speed of Coarse Particles determined by according to Newton's Law?

$\frac{8m^2gD}{3m}$ Signup and view all the answers

Which of the following sizes classifies particulates as Nonrespirable?

$> 7 \mu m$ Signup and view all the answers

What kind of dust is harmful due to alpha and beta radiation emissions?

Radioactive Dust Signup and view all the answers

What is the purpose of the hairs in the nasal passage according to the text?

To trap larger dust particles during inhalation Signup and view all the answers

Which part of the respiratory system is responsible for blood oxygenation?

Alveoli Signup and view all the answers

How does exposure time to dust relate to dust-related illnesses according to the text?

Exposure time of over 20 years could lead to dust-related illnesses Signup and view all the answers

How do individual peculiarities influence the harmfulness of dust according to the text?

They influence the degree of harmfulness of dust Signup and view all the answers

What is the function of bronchioles in the respiratory system?

Conducting air into the lungs Signup and view all the answers

What is the role of mucous membrane in the nose and throat regarding dust particles?

Trapping more dust particles (large and small) Signup and view all the answers

What is the Dustability Index defined as?

D = f(B) f(H) Signup and view all the answers

Which of the following factors does Dust Formation depend on?

Season and time of the day Signup and view all the answers

What does the Dust Forming Index equation DFI = f(B) f(I) f(H) represent?

The factors influencing dust production Signup and view all the answers

Which parameter for characterizing dust depends on the chemical composition of the dust?

The surface area of dust per unit volume Signup and view all the answers

How does dust remain suspended in a gaseous medium for a long time?

Because of its small particle size Signup and view all the answers

What does the hardness of a substance (Vicker's hardness 'H') contribute to in terms of dust formation?

The movement of rock dust particulates Signup and view all the answers

Study Notes

Terminal Velocity of Particles

The terminal velocity of coarse particles (> 200 μm) is determined by Newton's Law: VN = √(8mg)/(3m2) where VN is the terminal velocity, m is the mass of the particle, g is the acceleration due to gravity, and m1 and m2 are the masses of the particle and air, respectively.

Classification of Particulates

Particulates can be classified as Respirable (< 7 μm) and Nonrespirable (> 7 μm) from a health hazard point of view.
Harmfulness of dust can be classified into:
- Fibrogenic Dusts: Pulmonary dust that is harmful to the lower respiratory system, e.g., silica, quartz.
- Carcinogenic Dust: Pulmonary dust that harms the upper respiratory system, e.g., radon daughters, asbestos, arsenic.
- Toxic Dust: Poisonous to body organs, tissues, etc., e.g., Beryllium, Arsenic, Lead.
- Radioactive Dust: Injurious due to alpha and beta radiation emissions, e.g., uranium, radium, thorium.
- Explosive Dust: Combustible when airborne in sufficient quantities, e.g., metal dust, coal dust, sulphide ore dust.

Factors that Determine the Harmfulness of Dust

Composition of dust, including chemical and mineralogical composition.
Concentration of dust in the atmosphere.
Particle size.
Exposure time: usually, exposure to dust for over 20 years could lead to dust-related illnesses, though it is possible after shorter durations.
Individual susceptibility: health status and other individual peculiarities influence the degree of harmfulness of dust.

Pathological Effects of Dust

The human respiratory system has built-in safeguards to protect the sensitive tissue in the lungs from the harmful effects of dust particles.
In the upper respiratory system, filters involve:
- Hairs in the nasal passage filter out larger particles (over 10 μm in size).
- The mucous membrane lining the nose and throat traps more dust particles.

Characteristics of Dust

Dust particles have sizes, shapes, and structural features.
Parameters to characterize dust include:
- The number of particles per unit volume.
- The size distribution of the particles.
- The mass of dust per unit volume.
- The surface area of dust per unit volume.
- The chemical composition of the dust.
- The mineralogical nature of the particles.

Formation and Movement of Rock Dust Particulates

Formation and movement of rock dust particulates depend on:
- Brittleness of the substance (B).
- The hardness of the substance (Vicker's hardness H).
- The force applied to the substance.
A Dustability Index is defined as D = f(B) / f(H).
A Dust Forming Index is also defined as: DFI = f(B) × f(I) / f(H) = D × f(I) where I is the induced factor causing dust production.

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Description

Test your knowledge on the characteristics of dust particles in a gaseous medium. Learn about their dispersion, suspension, surface area-to-volume ratio, and how they can be characterized using parameters like particle number, size distribution, mass, surface area, and chemical composition.