Atmospheric Carbon Particles and the Los Angeles Visibility Problem

Abstract

The control of atmospheric primary carbonaceous particles is central to protecting visibility. In the Los Angeles area, fine particulate carbon accounts for 40% of fine particulate mass concentration on an annual average basis and 33% of the fine aerosol mass during summer midday periods. Visibility modeling shows that aerosol carbon contributes up to 39% of the total scattering coefficient and up to 44% of the extinction coefficient in the Los Angeles area during summer midday periods. Using the results of the primary aerosol carbon emission control strategy study by Gray (1986), which determined the least costly set of controls necessary to achieve reduced levels of primary carbonaceous aerosol in the Los Angeles area, it is estimated that an 8%–14% decrease in the average 1984 summer midday extinction coefficient could be achieved at Pasadena if primary aerosol carbon emission controls costing $80.4 × 10⁶ year⁻¹ (1982 dollars) had been in place at that time. An 11%–19% decrease in the extinction coefficient is estimated to result from controls costing $423.5 × 10⁶ year⁻¹ (1982 dollars).