Of all the problems of conservation, none is more urgent that the polluted air which endangers the American people. We have been fortunate so far. But we have seen that when winds fail to blow, the concentrations of poisonous clouds over our cities can become perilous.
Johnson, Lyndon B. (1970). “Public Papers of the Presidents of the United States: Lyndon B. Johnson, 1968-1969”, p.361, Best Books on
