National Air Surveillance Network NASN

Sheppard 1980). The level of thorium measured in 1969 in East Chicago, IN, a heavily polluted industrial area, was 1.3 ng/m compared to a value of 0.27 ng/m at a rural location in Michigan (Niles, Ml) (Dams et al. 1970). The air particulate samples collected from 250 sites in the United States by the National Air Surveillance Network (NASN) of ERA during 1975 and 1976 were analyzed for thorium-232 by neutron activation analysis. The measured concentrations at 250 urban and nonurban sites in the United States ranged from 0.2-1.0 ng/m, with a mean concentration of 0.3 ng/m (Lambert and Wilshire 1979). The mean concentrations of thorium-228, thorium-230 and thorium-232 in New York City air (sample collected on the roof above the 14th floor) were 36 aCi/m (aCi = 10 Ci), 36 aCi/m, and 37 aCi/m, respectively (Wrenn et al. 1981). 

The carbon analyzer has been used to analyze filters from 42 urban sites and 22 non-urban sites in the United States. These filters were obtained from the National Air Surveillance Network (NASN) filter bank for 1975. Carbon concentrations and mass fractions for Detroit, Michigan, are shown in Figures 5 and 6. Both the organic and elemental carbon concentrations are highly variable, and no seasonal trends are apparent. For this site elemental carbon constituted 38% of total aerosol carbon. Typical values for other sites ranged between 35 and 55%. 

In 1953 the Public Health Service in cooperation with state and local departments in air-pollution control agencies set up air sampling stations in 17 communities. The Federal Air Pollution Research and Technical Assistance Act (Public Law 159, 84th Congress) became effective in June, 1955. The network expanded to become national in 1957, at which time about 110 urban and 51 non-urban stations in the 50 states, the District of Columbia, and the Commonwealth of Puerto Rico were operated on a continuing basis. Currently, the National Air Surveillance Network (NASN) includes some 270 stations (10% of which are non-urban) where particulate matter is collected on glass-fiber filters and TSP is deter-... 

Van De Velde K, Ferrari C, Barbante C, Mret I, Bellomi X Hong S, and Boutron C (1999) A 200 year record of atmospheric cobalt, chromium, molybdenum, and antimony in high altitude alpine firn and ice. Environ SdTechnol 33 3495-3501. Var F, Narita Y and Tanaka S (2000) The concentration, trend and seasonal variation of metals in the atmosphere in 16 Japanese cities shown by the results of National Air Surveillance Network (NASN )from 1974 to 1996. Atmos Environ 34 2755-2770. VoELKER B, Morel F and Sulzberger B (1997) Iron redox cycling in surface waters ffects of humic substances and light. Environ Sd Tedmol 31 1004-1011. 

Ambient air Pb levels in the United States or elsewhere were not recorded or reported in any systematic way until the late 1950s. The establishment of the National Air Surveillance Network (NASN) in the United States was typical... 

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