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A provision in the Clean Air Act of 1970 requires the States to implement plans for maintaining the air quality on a regional basis and for enforcement of National Ambient Air Quality Standards (NAAQS). Airports must be included in the emission inventory, pollution levels must be monitored, and their impact on air quality assessed. Also, the location of new airports or alteration of existing ones requires the preparation of environmental impact statements. Up to the present time this information was based on mathematical pollution dispersion models and point values obtained from conventional point sampling devices, both of which have inherent difficulties in terms of data acquisition and subsequent interpretation. Remote laser systems offer the potential of overcoming previous difficulties. A comprehensive study was undertaken to determine which laser systems could be most useful in the airport environment. The performance of the different methods was investigated, as they relate to airport monitoring, to determine their capability to measure air pollutants within the requirements of the NAAQS. It was found that of the different laser methods under development, for measuring gaseous pollutants, only the differential absorption by scattering (DAS) and the long-path transmission (LPT) methods appear to be useful, while the Raman scattering and fluorescence methods do not have sufficient sensitivity and, hence, are range limited. The advantages and disadvantages of the DAS and LPT are discussed in detail. A critical performance analysis shows that the DAS method has just enough sensitivity under the constraints of the HEW eye safety regulations to measure the primary pollutants within the levels of the NAAQS up to distances of several hundred meters. In contrast, the LPT method has a greatly improved sensitivity above DAS, but is limited in its three-dimensional application and lacks the ability of range resolution. It was further found that for measuring particles, lidar systems are applicable, provided that a satisfactory relationship between optical parameters and mass density can be established.
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