Reducing Greenhouse Gas Emissions and Improving Air Quality
28
28
gas is an irritant which impacts health. Additionally, nitrogen oxides are
involved in the formation of smog and ozone. Nitrogen dioxide combines
with water to form acid rain, which has environmental impacts that include
damage to vegetation. Nitrogen oxides can react with ammonia and other
air pollutants to form solids such as ammonium nitrate and thus become
particulate matter in the air (EEA, 2018; Wang et al., 2015). Nitrogen in particulate matter in Beijing, China was mostly attributed to coal combustion,
vehicle emissions, dust, and animal waste (Wang et al., 2017).
Ammonia gas is an important pollutant in urban air in some locations
because it contributes significantly to secondary particle formation when
it reacts with oxides of nitrogen or sulfur to form small solid particles.
The PM2.5 concentration in Shanghai includes sulfate- nitrate- ammonium
aerosols because ammonia reacts with oxides of sulfur to form ammonium sulfate and oxides of nitrogen to form ammonium nitrate (Wang
et al., 2015). Shanghai has a population of about 24 million, and haze
pollution is present in the cold of winter and in spring due to particulate
matter that is emitted by combustion processes and from the formation
of secondary particulates in the air. The ammonia emissions in Shanghai
are from industrial, agricultural, and other sources. Concentrations above
10 ppb are present in some parts of Shanghai. Reductions in ammonia
emissions have the potential to contribute to reduced PM2.5 in the urban
air in Shanghai (Wang et al., 2015).
3.2.3 Smog and Ozone
Smog and ozone formation in polluted air is a major problem in many
large cities. As mentioned previously, nitrogen oxides react with VOCs
such as vapors from fuels and solvents in sunlight to produce ozone and
other compounds. The level of ozone in air can be reduced by addressing
the sources of nitrogen oxides and VOCs so that the concentrations of these
reactants in the air are lowered. In Los Angeles, for instance, ozone levels
were as high as 600 ppb in the 1960s; however, as a result of continuing
efforts to reduce the concentration of sources, ozone levels were reduced to
below 200 ppb by about 1998. Ozone levels in Los Angeles are continuing
to decrease (Baklanov et al., 2016; Parrish et al., 2016), although the values
remain above the new national ambient eight- hour ozone standard of 70 ppb
during many days each year (Parrish et al., 2016).
Air pollution has been recognized as a very important issue in Los Angeles,
California since the 1950s. Parrish et al. (2016) report that there has been significant progress in reducing concentrations of ozone, VOCs, NO x , and PM2.5
in Los Angeles and the surrounding communities because of a concerted
effort to improve air quality. The progress in Southern California has been
accomplished because of long- term efforts to control all air pollution sources,
unified policies, and consistent and effective enforcement (Parrish et al.,
2016). Controlling emissions from transportation vehicles is particularly
28
28
gas is an irritant which impacts health. Additionally, nitrogen oxides are
involved in the formation of smog and ozone. Nitrogen dioxide combines
with water to form acid rain, which has environmental impacts that include
damage to vegetation. Nitrogen oxides can react with ammonia and other
air pollutants to form solids such as ammonium nitrate and thus become
particulate matter in the air (EEA, 2018; Wang et al., 2015). Nitrogen in particulate matter in Beijing, China was mostly attributed to coal combustion,
vehicle emissions, dust, and animal waste (Wang et al., 2017).
Ammonia gas is an important pollutant in urban air in some locations
because it contributes significantly to secondary particle formation when
it reacts with oxides of nitrogen or sulfur to form small solid particles.
The PM2.5 concentration in Shanghai includes sulfate- nitrate- ammonium
aerosols because ammonia reacts with oxides of sulfur to form ammonium sulfate and oxides of nitrogen to form ammonium nitrate (Wang
et al., 2015). Shanghai has a population of about 24 million, and haze
pollution is present in the cold of winter and in spring due to particulate
matter that is emitted by combustion processes and from the formation
of secondary particulates in the air. The ammonia emissions in Shanghai
are from industrial, agricultural, and other sources. Concentrations above
10 ppb are present in some parts of Shanghai. Reductions in ammonia
emissions have the potential to contribute to reduced PM2.5 in the urban
air in Shanghai (Wang et al., 2015).
3.2.3 Smog and Ozone
Smog and ozone formation in polluted air is a major problem in many
large cities. As mentioned previously, nitrogen oxides react with VOCs
such as vapors from fuels and solvents in sunlight to produce ozone and
other compounds. The level of ozone in air can be reduced by addressing
the sources of nitrogen oxides and VOCs so that the concentrations of these
reactants in the air are lowered. In Los Angeles, for instance, ozone levels
were as high as 600 ppb in the 1960s; however, as a result of continuing
efforts to reduce the concentration of sources, ozone levels were reduced to
below 200 ppb by about 1998. Ozone levels in Los Angeles are continuing
to decrease (Baklanov et al., 2016; Parrish et al., 2016), although the values
remain above the new national ambient eight- hour ozone standard of 70 ppb
during many days each year (Parrish et al., 2016).
Air pollution has been recognized as a very important issue in Los Angeles,
California since the 1950s. Parrish et al. (2016) report that there has been significant progress in reducing concentrations of ozone, VOCs, NO x , and PM2.5
in Los Angeles and the surrounding communities because of a concerted
effort to improve air quality. The progress in Southern California has been
accomplished because of long- term efforts to control all air pollution sources,
unified policies, and consistent and effective enforcement (Parrish et al.,
2016). Controlling emissions from transportation vehicles is particularly