approximately 2.1 km per decade from 1981 to 2005 in which the reduction
accelerated after 1990 (Che et al. 2009). In 2010 over 80% of population lived in
regions where air quality was poor (Apte et al. 2015). In January 2013, a persistent
and severe haze event occurred in China, which covered approximately 1.4 million
km
2 and affected 800 million people (Huang et al. 2014; Tian et al. 2014). The daily
average concentrations of particulate matter with an aerodynamic diameter of 2.5 μm
or smaller (PM 2.5 ) exceeded the National Ambient Air Quality Standards (NAAQS)
of 75 μg∙m
À3 for 69% of days in the month, with a max daily concentration of
772 μg∙m
À3 (Guo et al. 2018). This extreme haze event was the turning point of
public concern for haze in China (Lu et al. 2018).
Haze pollution can reduce visibility (Zhao et al. 2011b), change the regional
climate by altering solar radiation (Yao et al. 2018b), and influence natural and
agricultural ecosystems (Chameides et al. 1999). In addition to the above effects, the
associated health risk is probably the most important public concern regarding haze
pollution. Short-term exposure to atmospheric fine particles has effects on the
respiratory system, lung function, and the cardiovascular system (Habre et al.
2018). PM 2.5 was identified as a leading risk factor for the global disease burden
with an estimated 2.9 million attributable deaths in the year 2013 (Forouzanfar et al.
2015). Long-term exposure also has stronger effects and may lead to other
unidentified consequences to public health (Yitshak-Sade et al. 2018). Xue and
Zhu (2018) found a linear relationship between the increment of ambient exposure
to fine particles and the reduced human fertility rate in China from 2000 to 2010. In
addition, ambient PM 2.5 exposure during pregnancy played an important role in the
pregnancy process and increased the risk of preterm birth in China (Guo et al. 2018).
On the global scale and in 2013, 87% of the population lived in areas where the
annual average PM 2.5 exceeds the World Health Organization Air Quality Guideline
of 10 μg∙m
À3 . The global population-weighted PM 2.5 increased by 20.4% between
1990 and 2013, which had been driven by increasing trends in South Asia, Southeast
Asia, and China (Brauer et al. 2016).
Ammonia (NH 3 ), amines, and nitrogen oxides (NO x ) are main components of
reactive nitrogen (Nr), which participate actively in physiochemical reactions in the
atmosphere. The atmospheric levels of Nr have increased significantly after the
industrial revolution due to anthropogenic activities (Zhang et al. 2017b). These
pollutants are well-known for their contribution to various environmental issues,
especially their participation in haze formation. The goal of this chapter is to
introduce the role of atmospheric Nr in haze formation, including the mechanisms
involved and the contribution of Nr. The mitigation effects on haze pollution are also
evaluated based on observations and atmospheric modeling.
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Y. Pan et al.
accelerated after 1990 (Che et al. 2009). In 2010 over 80% of population lived in
regions where air quality was poor (Apte et al. 2015). In January 2013, a persistent
and severe haze event occurred in China, which covered approximately 1.4 million
km
2 and affected 800 million people (Huang et al. 2014; Tian et al. 2014). The daily
average concentrations of particulate matter with an aerodynamic diameter of 2.5 μm
or smaller (PM 2.5 ) exceeded the National Ambient Air Quality Standards (NAAQS)
of 75 μg∙m
À3 for 69% of days in the month, with a max daily concentration of
772 μg∙m
À3 (Guo et al. 2018). This extreme haze event was the turning point of
public concern for haze in China (Lu et al. 2018).
Haze pollution can reduce visibility (Zhao et al. 2011b), change the regional
climate by altering solar radiation (Yao et al. 2018b), and influence natural and
agricultural ecosystems (Chameides et al. 1999). In addition to the above effects, the
associated health risk is probably the most important public concern regarding haze
pollution. Short-term exposure to atmospheric fine particles has effects on the
respiratory system, lung function, and the cardiovascular system (Habre et al.
2018). PM 2.5 was identified as a leading risk factor for the global disease burden
with an estimated 2.9 million attributable deaths in the year 2013 (Forouzanfar et al.
2015). Long-term exposure also has stronger effects and may lead to other
unidentified consequences to public health (Yitshak-Sade et al. 2018). Xue and
Zhu (2018) found a linear relationship between the increment of ambient exposure
to fine particles and the reduced human fertility rate in China from 2000 to 2010. In
addition, ambient PM 2.5 exposure during pregnancy played an important role in the
pregnancy process and increased the risk of preterm birth in China (Guo et al. 2018).
On the global scale and in 2013, 87% of the population lived in areas where the
annual average PM 2.5 exceeds the World Health Organization Air Quality Guideline
of 10 μg∙m
À3 . The global population-weighted PM 2.5 increased by 20.4% between
1990 and 2013, which had been driven by increasing trends in South Asia, Southeast
Asia, and China (Brauer et al. 2016).
Ammonia (NH 3 ), amines, and nitrogen oxides (NO x ) are main components of
reactive nitrogen (Nr), which participate actively in physiochemical reactions in the
atmosphere. The atmospheric levels of Nr have increased significantly after the
industrial revolution due to anthropogenic activities (Zhang et al. 2017b). These
pollutants are well-known for their contribution to various environmental issues,
especially their participation in haze formation. The goal of this chapter is to
introduce the role of atmospheric Nr in haze formation, including the mechanisms
involved and the contribution of Nr. The mitigation effects on haze pollution are also
evaluated based on observations and atmospheric modeling.
114
Y. Pan et al.