The consciousness of inhabitants in Isogo Ward, Yokohama City about air pollution was surveyed in 1969 and 1973. A group of industrial factories was partly in operation in 1969 but was in full operation by 1973. Fortunately there was very slight difference in sex ratio, age, occupation, health condition, and smoking habits of the objects between 1969 and 1973. The survey was performed by questionnaires consisting of 43 items. The percentage of positive answers to human impairments in 1969 and 1973 were: 38.7 and 34.2 experience of health damage; 8.1 and 5.4 of eye-irritation; 16.1 and 14.5 of throat-irritation; 5.8 and 13.6 of sneeze; 4.2 and 2.3 of snivel; 9.2 and 10.2 of cough; 3.6 and 17.1 of dyspnea; 5.4 and 7.4 of asthma; and 22.2 and 5.7 of odor. Generally, the largest source of air pollution in this area was auto exhaust followed by factory-exhaust, and the change of inhabitants consciousness about air pollution pointed out the situation. Most inhabitants were pessimistic about the future status of air pollution in the surveys in 1969 and also in 1973.