Page 39 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

12 1 Air Emissions

Fig. 1.1 US energy historical use and projection by fuel type (1949–2040)

1.4.4 Global Air Emissions

Before the 1980s, air pollution was mainly a local concern; and, strict national
industrial controls in developed countries led to a significant reduction in air
emissions and improved the air quality in urban areas. For example, the US Clean
Air Act of 1970 was passed to address the increasing concerns of air pollution.
Similar changes took place throughout the industrialized world at that time, and the
ambient air quality has improved locally in developed countries. In a modern world,
air emissions should be considered from a global perspective. While some people
enjoy the comfort and speed of modern conveniences and luxuries provided by
energy consumption, others are suffering from the resulting air emissions, with or
without intention. There is no doubt that fossil fuel is and will remain the dominant
source of global energy in the coming decades. The demand of fossil fuels is still
growing, as is the output of air emissions.
Global air pollution continues to worsen due to the population growth and scant
environmental restrictions in many nations. The situation is worse in the developing
countries, especially for the emerging economies. Figure 1.2 shows the map of
global air pollution using PM 2.5 as an indicator [28]. As seen in Fig. 1.2, recent
rapid unsustainable economic development has also resulted in considerable air
pollution in China. Many Chinese cities often seem wrapped in toxic gray shrouds,
and visibility is extremely low most of the time. Ninety-nine percent of the city
dwellers in China breathe air that is considered to be polluted by the European
Union [16].