Census data above from 1910, in "The Challenge of Pittsburgh" (1917)
Immigrants were the first Pirate fans down at the old Exposition Park.
"These city inspectors study heavy clouds billowing from a steel mill's chimneys. Smoke is viewed with special glasses and through a hole in a Ringelmann Chart. Density is graded by matching it with shades ranging from light gray to black on the card."
"At Pittsburgh's Mellon Institute a researcher prepares to feed contaminated air to an assistant, Nancy Butler, in an iron lung. Plastic bags collect the air mixtures. Results are registered on an ingenious guage. Careful control of the flow protects Miss Butler from danger."