Air quality management efforts in the United States are guided by the NAAQS, which are set based on health and welfare effects of the major air pollutants: particulate matter (PM), ozone (O3), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), and lead. Standards for PM have been established for two size categories: PM of less than 10 microns in aerodynamic diameter (PM10) and PM of less than 2.5 microns in diameter. Likewise, air quality management efforts in China are guided by National Air Quality Standards, which have been established for SO2, NO2, and PM10. The current health-based NAAQS are listed in Table 3-1, along with air quality standards adopted by China (Table 3-2) and guidelines established by the World Health Organization (WHO) (Table 3-3). In addition to efforts focused on these major air pollutants, both countries are also concerned with toxic air pollutants that are less ubiquitous. These toxic air pollutants (or hazardous air pollutants, as they are called in the Clean Air Act) include benzene and other aromatic compounds from motor vehicles, fuels, and other combustion sources, and mercury from solid waste and coal combustion.

China has developed an Air Pollution Index (API) based on its air quality standards, and cities use this tool to report their air quality (see Chapter 4, Table 4-1). Like their national standards, the API contains classes (I-V) which allow cities to comply at various levels. Cities are encouraged to achieve Class II standards

TABLE 3-1 U.S. National Ambient Air Quality Standards (NAAQS)

Pollutant

Primary Stds.

Averaging Times

Secondary Stds.

Carbon monoxide

9 ppm (10 mg/m3)

8-hour

None

 

35 ppm (40 mg/m3)

1-hour

None

Lead

1.5 µg/m3

Quarterly average

Same as primary

Nitrogen dioxide

0.053 ppm

Annual (arithmetic mean)

Same as primary

 

(100 µg/m3)

 

 

Particulate matter (PM10)

Revoked

Annual (arith. mean)

 

 

150 µg/m3

24-hour

 

Particulate matter (PM2.5)

15.0 µg/m3

Annual (arith. mean)

Same as primary

 

35 µg/m3

24-hour

 

Ozone

0.08 ppm (171 µg/m3)

8-hour

Same as primary

 

0.12 ppm (257 µg/m3)

1-hour (Applies only in limited areas)

Same as primary

Sulfur oxides

0.03 ppm (78 µg/m3)

Annual (arith. mean)

 

0.14 ppm (364 µg/m3)

24-hour

 

3-hour

0.5 ppm (1300 µg/m3)



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