Basic Properties of Air & Airborne Contaminants (Module 3)

Question 1

What are the types of airborne contaminants?

Answer 1

• Gases and vapors
• Aerosols

Question 2

What state are gases in at room temp?

Answer 2

Gases are in a gaseous state at room temperature

Question 3

What state are vapors in at room temp?

Answer 3

Vapors can be either solids or liquids at room temperature

Question 4

What is airborne behavior for gases and vapors influenced by?

Answer 4

density differences (vs air) and temperature, leading (possibly) to possible buoyancy effects

Question 5

What are aerosols?

Answer 5

Liquid or solid particles suspended in air

Question 6

What is airborne behavior for aerosols influenced by?

Answer 6

Airborne behavior influenced by inertia, gravity, diffusion, and (sometimes) electrostatic effects

Question 7

What are examples of respiratory hazards?

Answer 7

• Oxygen deficient atmospheres
• Hazard of airborne contaminants (aerosols, gasses, and vapors)
• Some toxic aerosols or gases do not affect the lung tissue locally, but have adverse effects on other body organs or on the oxygen-carrying capacity of the blood cells

Question 8

What is the upper respiratory tract composed of?

Answer 8

• nose
• pharynx
• larynx

Question 9

What do the middle and lower respiratory tracts consist of?

Answer 9

• trachea
• all segments of the bronchial tree
• the alveoli

Question 10

What does the aerodynamic sizes determine?

Answer 10

Where the particles are deposited in the respiratory tract

Question 11

How do gases absorb and deposit in the respiratory tract?

Answer 11

• Very water-soluble gaseous chemicals may only reach the upper respiratory tract.
• Less water-soluble gaseous chemicals may reach the lower respiratory tract.

Question 12

How do aerosols absorb and deposit in the respiratory tract?

Answer 12

• Large particles can only deposit in the upper respiratory tract.
• Small particles can reach the lower respiratory tract.

Question 13

What are the emission sources for aerosols/particulates?

Answer 13

• mechanical actions
• chemical actions

Question 14

What is the basic form of gases?

Answer 14

molecules mix with air and diffuse to (eventually) fill the space containing them

Question 15

What is the basic form of vapors?

Answer 15

gaseous emissions from liquid surfaces – molecules escape

EX: boiling liquids, cold liquids in open-top containers, airborne droplets

Question 16

What is vapor pressure?

Answer 16

• Influences the tendency of liquid molecules to escape from the liquid surface and become vapor in the air

-high vapor pressure → more volatile

Question 17

What is volatility (vapor pressure)?

Answer 17

-tendency to evaporate

Question 18

What are the critical exposure factors for gases and vapors?

Answer 18

• Concentration
• Exposure time
• Mode of use and potential for exposure
• Temperature and volatility
• Reactivity

Question 19

What are examples of aerosols?

Answer 19

• Dust
• spray
• mist
• fume
• smoke
• bioaerosol

Question 20

What is dust? (aerosol)

Answer 20

• solid particles made airborne by mechanical disintegration of solid material
• sub-μm to over 100 μm

Question 21

What is spray? (aerosol)

Answer 21

• large liquid droplets produced by mechanical disruption of bulk liquid
• sub-μm to up to about 40 μm

Question 22

What is mist? (aerosol)

Answer 22

• finer liquid droplets produced during condensation or atomization
• sub-μm to a few μm

Question 23

What is a fume? (aerosols)

Answer 23

• small solid particles produced by condensation of vapors or gaseous combustion products (primary particles), usually followed by coagulation (aggregates)
• up to about 1μm

Question 24

What is smoke? (aerosol)

Answer 24

• small particles produced by incomplete combustion, usually in the form of aggregates following condensation and coagulation
• up to about 1μm

Question 25

What is a bioaerosol? (aerosol)

Answer 25

- solid or liquid particles consisting of, or containing biologically- viable organisms (viruses, bacteria, allergens, fungi, etc.) - sub-μm up to 100 μm

Question 26

What are some examples of aerosols in the workplace?

Answer 26

- Cutting or extraction of bulk solid mineral material (e.g., coal, ore, etc.) - Cutting (or otherwise working/machining), handling, conveying solid material (e.g., bulk chemicals production, agriculture, etc.) - Milling, smelting or refining (e.g., metals primary production) - Textiles production (e.g., batching, carding, spinning or weaving) - Welding, soldering, brazing, etc.

Question 27

Does a bigger or smaller particle settle faster?

Answer 27

Bigger, smaller stays suspended for longer

Question 28

What is problem characterization?

Answer 28

Study of emission sources, worker behavior, and air movement

Question 29

What are controls for problem characterization based on?

Answer 29

emission sources, air movement, and worker behavior

Question 30

Problem Characterization in Predesign Phase: Emission Source

Answer 30

- Location of emission sources - Which emission sources and in what ratios actually contribute to exposure - Characterization of each source: chemical composition, temperature, rate of emission, direction of emission, initial emission velocity, continuous of intermittent, time intervals of emission

Question 31

Problem Characterization in Predesign Phase (Air)

Answer 31

- Air temperature - Air movement - Mixing potential - Supply and return flow conditions - Air changes per hour - Effects of wind speed and direction - Effects of weather and season

Question 32

Problem Characterization in Predesign Phase (Worker)

Answer 32

- Worker interaction with the emission source - Worker location - Work practice - Worker education, training, cooperation