Environmental Science 102
Air Pollution

Air Pollution

What is air pollution?

Brief History of Air Pollution

First human produced air pollution begins when humans first use fire.
Early accounts of air pollution characterize it a "smoke problems"
In 1273, King Edward I Longshanks of England banned the use of sea coal because of the smoke it produced
- the first "Clean Air Act"
By 1850 the Industrial Revolution had started in Europe and North America
London became known for its "pea-soup" fog - not a true fog, but a mixture of fog and smoke
In 1873 one such fog killed 700 people
In 1911 another killed 1150 people
- at this time a London physician, Harold Des Voeux, coined the term "smog" - smoke and fog
In 1952 nearly 4000 people died in one of the killer smogs.

Clean Air Acts

Great Britian passes its first Clean Air Act in _____.
United States passes its first Clean Air Act in _____.

EPA and the Clean Air Act

Mission: Protect human health and the environment
Key Elements of the Clean Air Act
Reduce outdoor concentrations of air pollutants
Reduce emissions of toxic air pollutants
Phasing out production and use of chemicals that destroy stratospheric ozone.

EPA: Air Quality Index

An index for reporting daily air quality.
Calculated based on five major air pollutants:

6 Levels of Air Quality

AQI Value Level Meaning
0 - 50 Good Air quality is considered satisfactory, and air pollution poses little or no risk.
51 - 100 Moderate Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
101 - 150 Unhealthy for Sensitive Groups Members of sensitive groups may experience health effects. The general public is not likely to be affected.
151 - 200 Unhealthy Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
201 - 300 Very Unhealthy Health warnings of emergency conditions. The entire population is more likely to be affected.
301 - 500 Hazardous Health alert: everyone may experience more serious health effects.

Today’s AQI

Calculating AQI

Guidelines for the Reporting of Daily Air Quality – the Air Quality Index (AQI) - EPA PDF file

Indoor Air Quality

Indoor levels of air pollutants may be 2-5 to more than 100 times higher than outdoor levels.
Most people spend as much as _______ of their time indoors.
Common sources can include:

Types and Sources of Air Pollutants

Carbon Monoxide - CO
A colorless, odorless, poisonous gas
Dangerous because red blood cells will more readily carry CO than oxygen, O2

Sulfur Dixide - SO2
Colorless gas, produced by combustion of sulfur bearing fossil fuels (coal, oil)
Primary sources:
Natural sources:

Nitrogen Oxides - NOx
Forms during high temperature combustion of fuel
Nitrogen dioxide - NO2
Nitric oxide - NO
Nitrogen dioxide reacts with water to form Nitric Acid - HNO3
Nitric acid is a main component of acid rain
Primary sources:
Natural source:

Compounds composed dominantly hydrogen, H and carbon, C
Methane, CH4 is a hydrocarbon
Benzene, formaldehyde, benzo-a-pyrene and CFCs
Many hydrocarbons are carcinogenic

Any solid or liquid particle

Temperature Inversions

Temperature inversions can trap smog and pollutants
Inversions occur when the temperature of an air mass increases with increasing altitude instead of decreasing as it normally does.
Convection occurs in an air mass because warm air rises.
In an inversion, the warm pollutants are unable to rise becuase itquickly reaches the temperature of the surrounding air.

Pollution Domes and Plumes

Pollution domes develop around sources of pollution (city or industrial complexes) when there is a stable air mass (no wind) - the pollutants remain over the source forming a dome of pollution.
Pollution plumes develop when wind carries the pollutants away from the source area.

Global Dimming

Measurements from light meters and pan evaporation rates.
Since 1950, solar radiation has decreased by 9 to 30% on various parts of the globe.
Caused by:
Can adversely affect rainfall and global warming.