Chapter 6: Air Pollution

Question 1

How much air do we breath in a day? When exercising?

Answer 1

14,000L, approximately 26,000 times a day. When exercising, 4x more.

Question 2

Examples of microscale pollution

Answer 2

Construction materials (wood, coal, gas), pathogens, radioactive materials, poor ventilation

Question 3

Examples of mesoscale pollution

Answer 3

Industrial plants, cars

Question 4

Examples of macroscale pollution

Answer 4

Acid rain, ozone depletion, global warming

Question 5

Size of gaseous pollutants

Answer 5

< 5 nm

Question 6

Size of particulates

Answer 6

> 50 nm

Question 7

Air pollution

Answer 7

Chemicals added to the atmosphere by natural events or human activities in high enough concentrations to be harmful

Question 8

Primary air pollutant

Answer 8

Harmful substance that is emitted directly into the atmosphere

Question 9

Secondary air pollutant

Answer 9

Harmful substance formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants

Question 10

Air Point sources

Answer 10

Any single identifiable source of pollution from which pollutants are discharged, (EX: Power plants, factories)

Question 11

Air Nonpoint sources

Answer 11

Diffuse pollution of air that does not originate from a single discrete source. Cumulative. (EX: Exhaust fumes)

Question 12

Carbon monoxide (CO)

Answer 12

Colorless, odorless gas that is lethal to humans at 5000 ppm for a few minutes.

Question 13

HAPS

Answer 13

Many chemicals that cause a variety of diseases/cancers from industrial and atmospheric sources (EX: asbestos, arsenic)

Question 14

Lead

Answer 14

Accumulative pollutant which causes anima and brain damage. Sourced from gasoline, paint, volcanic activity, airborne soil, smelters and refining processes

Question 15

Nitrogen oxides (NOX)

Answer 15

:Smog from bacterial activities in soil, combustion reaction in cars, power plants. Causes cough and irritation

Question 16

Photochemical Oxidants

Answer 16

Result in eye irritation, sourced from atmospheric reactions (secondary pollutants).

Question 17

Sulfure oxides (SOX)

Answer 17

Cause respiratory symptoms from biological decay, volcanoes, power plants, industry.

Question 18

Photochemical smog

Answer 18

Smog produced when ultraviolet light from the sun reacts with nitrogen oxides in the atmosphere

Question 19

Peroxyacyl Nitrates (PANs)

Answer 19

Respiratory and eye irritants present in photochemical smog

Question 20

Bioaerosols and pathogens

Answer 20

Bacteria and viruses in aerosols (water in air) or fomites (surfaces)

Question 21

Air mixing methods (3)

Answer 21

1. Natural convection from heat
2. Forced convection from fans
3. Air mixing chambers

Question 22

Absorption

Answer 22

Mass transfer from gas to liquid (EX: Scrubbers)

Question 23

Adsorption

Answer 23

Mass transfer from gas to solid (EX: Silica gel, activated carbon and alumina)

Question 24

Selective catalytic reduction (SCR)

Answer 24

NOX control by anhydrous ammonia (reducing agent) being injected into exhaust.
1. 4NO + 4NH3 + O2 → 4N2 + 6H2O
2. 2NO2 + 4NH3 + O2 → 3N2 + 6H2O

Question 25

Filters

Answer 25

For particles < 5 μm
Deep bed filters are for clean gases and low volumes (EX: air conditioner). Bag house filters are for dirty industrial gas with high volumes.

Question 26

Electrostatic Precipitator (ESP) efficiency

Answer 26

> 95% efficiency for d > 1 μm and >99.5% efficiency for d > 5 μm

Question 27

Ozone depletion

Answer 27

Lower ozone shrunk by 2.5% from 1976 to 1986. Causes problem with human health, crop yields, forestry, climate change, wildlife, air pollution, etc. Caused by Chlorofluorocarbons (CFCs).

Question 28

Ozone recovery

Answer 28

Montreal Protocol (1987) began phasing out all ozone destroying chemicals. Full recovery will not occur until 2050.

Question 29

Acid rain

Answer 29

SO2, NOx and VOC emissions react with water vapor in the atmosphere and form acids that return to the surface as either dry or wet deposition