Lecture 1: Introduction to aerosols

Question 1

Define AEROSOL

Answer 1

• Suspension of solid/liquid particles in a gas

- Including BOTH the particles and the gas

Question 2

Define Bioaerosol

Answer 2

• An aerosol of biological origin
• • includes viruses, viable organisms, such as bacteria and fungi, and products of organisms, such as pollen and spores

Question 3

Define CLOUD

Answer 3

• A visible aerosol with defined boundaries

Question 4

Define DUST

Answer 4

• A visible aerosol with defined boundaries

Question 5

Define FUME

Answer 5

• A solid particle aerosol
• • formed by the condensation of vapors of gaseous combustion products
• • often found in clusters or chains of primary particles of usually less than 0.05 microns

Question 6

Define HAZE

Answer 6

• An atmospheric aerosol that affects visibility

Question 7

Define MIST & FOG

Answer 7

• Liquid-particle aerosols formed by condensation or atomization
• • particles are spherical with sizes ranging from submicron to about 200 microns.

Question 8

Define SMOG

Answer 8

1. General term for visible atmospheric pollution in certain areas
2. Photochemical smog refers to an aerosol formed in the atmosphere by the action of sunlight on hydrocarbons and oxides of nitrogen.
   - - particles are generally LESS than 1 or 2 microns

Question 9

Define SMOKE

Answer 9

• A visible aerosol resulting from incomplete combustion
• • may be solid or liquid, and typically less than 1 micron
• • may be agglomerated like fume particles

Question 10

Define SPRAY

Answer 10

• A droplet aerosol formed by the mechanical breakup of a liquid
• • particles are larger than a few microns

Question 11

Define PARTICULATE MATTER (PM)

Answer 11

• Criteria pollutant; as defined by NAAQS
• • the generic term for a broad class of chemically and physically diverse substances that exist as discrete particle in liquid droplets of solid forms in the air

Question 12

Classify PRIMARY AEROSOLS

Answer 12

particles that are introduced directly into the atmosphere

Question 13

Classify SECONDARY AEROSOLS

Answer 13

particles that are formed in the atmosphere by chemical reaction of gaseous components

Question 14

Classify HOMOGENOUS AEROSOL

Answer 14

aerosol, in which all the particles are chemically indentical

Question 15

Classify MONODISPERSE AEROSOL

Answer 15

aerosol, in which all the particles have the same size

Question 16

Classify POLYDISPERSE AEROSOL

Answer 16

aerosol, in which particles are in a wide range of sizes

Question 17

Describe PARTICLE SIZE

Answer 17

• Most important parameter for characterizing the behavior of aerosols
• • equivalent spherical diameter (ESD)
• • aerodynamic equivalent diameter (AED)

Question 18

Describe PARTICLE SHAPE

Answer 18

• Most liquid aerosol particles are spherical

- Most solid aerosol particles are irregular

Question 19

Describe PARTICLE DENSITY

Answer 19

• Mass per unit volume of the particle itself (kg/m^3; g/cm^3)
• • particle density does not equal concentration
• • aerosol density DOES equal concentration