Pollution, a cause for concern 55 years ago, too.
D000393:Air Pollutants / Q000506:poisoning*; D000395:Air Pollutants, Occupational / Q000506:poisoning*; D000769:Anesthesia, Inhalation; D000776:Anesthesiology / Q000266:history*; D002641:Chicago; D004781:Environmental Exposure; D049673:History, 20th Century; D006801:Humans; D009873:Operating Rooms / Q000592:standards
D000393:Air Pollutants; D000395:Air Pollutants, Occupational