**Acknowledgements**

forms. In the process, CO2 could react with abundantly available metal oxides such as MgO or CaO to form stable carbonates. These reactions are mostly exothermic and occur naturally.

> *CaO CO CaCO MgO CO MgCO* + ® + ®

CO2 could also react with calcium and magnesium silicates including forsterite and serpen‐

325 4 2 3 22

*Mg Si O OH CO MgCO SiO H O*

These reactions are slightly more favorable at low temperatures. This process occurs naturally over geologic time frames and is responsible for much of the earth's surface limestone.

In the chapter, we described the current and emerging technologies and strategies that are being used or proposed to control air pollutants. Control technologies and strategies could be classified into upstream and downstream controls. Upstream technologies and strategies are usually being used to control air pollution emitted from mobile sources such as transportation, agriculture, and construction activities. Downstream technologies are usually applied to control particulate matter and gaseous pollutants emitted from stationary sources. The upstream control exhibited more advantages concerning to cost and efficiency than the

The air pollutants including SOx and Pb emitted from transportation activities could be significantly reduced by controlling the precursor pollutants in raw materials. The NOx, CO, and hydrocarbon emissions from transportation activity could be reduced by the application of catalytic converters and the control of lubricant consumption. The strategies to reduce motorized transportation demand and improve the road quality and traffic flow decrease the energy consumption demand, leading to decrease in air pollution emission. The strategies to control livestock feeding, animal housing systems, manure storage systems, application of manure for crops and application of fertilizers and pesticides significantly reduced the emission of methane (CH4), nitrous oxide (N2O), and ammonia (NH3). The strategies to control construction activities including control of site planning, construction traffic, demolition

works, and site activities significantly reduced the emission of particulate matter.

To control particulate matter pollutants, the technologies including cyclone, wet scrubber, electrostatic precipitators, and fabric filter have been efficiency applied. Among them, electrostatic precipitator is the most advantageous method and widely applied in the United

( )3 3 2 2

+® + +

24 2 2 2

+® +

2 2

*Mg SiO CO MgCO SiO*

tinite by the following the reactions:

**5. Conclusion**

246 Current Air Quality Issues

downstream control.

2 3 2 3

> This work was supported by a grant from the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT, and Future Planning (2013R1A2A2A03013138).
