Pollution plumes recur seasonally downwind of the Indian subcontinent and Asian continent due to industrial and vehicular emissions, biomass burning, and wind-blown dust. These plumes have been well documented by field campaigns and satellite observations and the environmental implications of the Asian Brown Cloud have been widely publicized in a recently released UNEP report <UNEP and C4, 2002>. Recent field experiments, however, demonstrate that the U.S. pollution plume can be as intense (in terms of aerosol mass concentration, aerosol optical depth, and ozone mixing ratio) as those downwind of India and Asia affecting regional climate along the U.S. East Coast. The use of identical sampling protocols in these experiments has been key in eliminating sampling biases and making the data directly comparable.