A continuous high-pitched din — a bit whirring, a bit crunching — echoed over the Bottom, the residential sliver of Braddock, Pa., nearest to the industrial plants and the Monongahela River. It rose, indistinguishably, from the steel mill — the Edgar Thomson Steel Works, opened by Andrew Carnegie in 1875 and still operating — and the adjacent air separation plant, where gasses are piped into the mill or liquefied for shipment.

Also borne on the breeze was an unmissable acrid smell. It hung in the atmosphere on a Monday morning in April, over Washington Street. Not much was going on: Braddock, near Pittsburgh, had more than 20,000 inhabitants a century ago but now has fewer than 2,000. Still, some young people — Black, like four-fifths of the residents today — clustered around the Living Water Church, where a hearse parked outside indicated that a funeral was underway.

As I walked with the photographer LaToya Ruby Frazier — who grew up on Washington Street and made there the documentary work about her family, at once poetic and unflinching, that cemented her reputation — my nose and throat started to tingle.

“Oh yeah,” Frazier said. “The longer you’re here, the heavier it’s going to get.”

Braddock has a history of high levels of air pollution and respiratory disorders, as well as infant mortality. Pollution from the steel mill remains a public health concern: In 2022, U.S. Steel, which owns the plant, agreed to a $1.5 million fine and promised improvements in a settlement with the Environmental Protection Agency and county health authorities.

Frazier has the autoimmune disease lupus. “I shouldn’t be down here too long, because my health has been so adversely affected,” she said.

The smell thickened as we neared the factories. The gas plant occupies the site of Talbot Towers, the public housing complex where Frazier’s family lived when she was born, in 1982, and that was torn down in 1990. Across the street sits the brick husk of another church, where she attended Bible study. An inscription on its facade — “You must be born again! Of water and spirit” — has appeared in her photographs.