Page 28 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

Chapter 1
Air Emissions

1.1 Air

Air surrounds planet Earth and is held in place by gravity. Typical standard air is
defined as dry air at sea level, where the temperature and pressure are 15 °C and
101,325 Pa, respectively. The composition of standard air is given in Table 1.1 [4].
By mole or volume, standard air contains 78.08 % nitrogen, 20.95 % oxygen,
0.93 % argon, 0.0314 % carbon dioxide, and trace amounts of other gases. These
ratios change very little with location or time. Most of the time, however, atmo-
spheric air is not dry, and there is a moisture content of about 1 %. The moisture
content of the air presents in form of water vapor or liquid droplets or ice crystals.

1.2 Air Pollution and Greenhouse Gases

Air emissions include air pollution emissions and greenhouse gas (GHG) emissions.
Air pollution emissions, which are commonly referred to as air pollutants, are
species in the air that cause acute or chronic human health problems and negative
environmental impacts. GHGs are not toxic unless at extremely high concentrations,
but their higher-than-normal concentrations in the atmosphere may have resulted in
global warming and climate change with possible catastrophic consequences on
planet Earth.
Air pollution occurs when unwanted materials are added to the air, especially in
abundance, resulting in effects on the environment and health. In principle, these
unwanted materials may be anything in any phase, such as carbon dioxide (CO 2 ),
liquid droplets, and solid dust particles. A material is labeled as an air pollutant only
when it is against the interest of human beings. For example, sulfur dioxide (SO 2 )is
considered as an air pollutant due to its negative impact on the environment and
human health, which will be elaborated on shortly.

© Springer Science+Business Media Singapore 2014 1
Z. Tan, Air Pollution and Greenhouse Gases, Green Energy and Technology,
DOI 10.1007/978-981-287-212-8_1