PM2.5 Monitoring and Mitigation in the Cities of China

I n the past decade, the air quality of China has been drawing great concern in the face of the country's rapid economic development.Nowadays, suspended particulate matter (PM) is considered to be the most serious pollutant in the metropolitan areas around the world due to its adverse health effects, including cardiovascular diseases, respiratory irritation, and pulmonary dysfunction. 1-3In respect of PM, the fine PM (PM 2.5 : aerodynamic diameter of particle ≤2.5 μm) poses the greater health risks, compared with the coarse PM (PM 10 : aerodynamic diameter of particle ≤10 μm) because the increased surface areas have high potential to adsorb or condense toxic air pollutants (oxidant gases, organic compounds, and transition metals). 4China codified a PM 10 standard for ambient air quality in 1996, however, China does not have a PM 2.5 standard or emission rule at present.In December 2011, a severe debate focusing on PM 2.5 occurred among the experts, media and public in Beijing, China.This debate is dust storms, smog, fog, and haze events occurred in the north of China with a high frequency, recently, which was significantly attributed to PM 2.5 (Figure 1, a photo in Beijing, China).Actually, previous studies reported the PM 2.5 in the biggest cities of China was in the range of 20-80 μg/m 3 in the past decade, which highly exceeds U.S. PM 2.5 standards (primary standard: 15 μg/m 3 ; secondary standard: 35 μg/m 3 ).Based on the public requirement, in order to provide adequate health and environmental protection, the Ministry of Environmental Protection of the People's Republic of China decided to implement a national PM 2.5 monitoring program.This promotes China government to pay more attention to the common water and air pollution, rather than the climate change. 5 According to the Shengxian Zhou, Minister of China Environmental Protection Ministry, the monitoring program will be accomplished by "Four Steps": First, designate the areas of Beijing, Shanghai, Guangzhou, and 31 capital cities of provinces where compliance monitoring of PM 2.5 and ozone must be performed by 2012.Second, designate another 113 cities of high environmental standard and attention to start monitoring by 2013.Third, all the county level cities must start monitoring the PM 2.5 by 2015.Fourth, a new emission rule and PM 2.5 standard based on the monitoring data will be executed