The unleashing of the fossil energy sector that Mr. Trump has championed could have repercussions more immediate than the global climate. In Houston, predominantly African-American neighborhoods like Sunnyside and Pleasantville have been dealing with pollution from the energy sector for years.

Ana Parras, her husband, Juan, and her stepson, Bryan, have been educating Houston residents about the dangers of living in communities surrounded by refineries and chemical plants. And they speak from experience. Ms. Parras recently began having breathing problems herself.

“Sometimes I can actually taste chemicals on my lips and I think to myself, ‘Maybe this is the price you pay for working and doing some of this stuff,’” Ms. Parras, 51, said as tears filled her eyes. “At the same time, I have even more empathy for these communities because a lot of these children have asthma and are sick.”

The Parras family has spent much of its time in Manchester, a community in Houston that is one of the most polluted places in the country. Because of Houston’s liberal land-use laws, the community is ringed by an oil refinery, a chemical plant, a car-crushing yard, a wastewater treatment plant and an interstate. In 2010, the Environmental Protection Agency found toxic levels of seven carcinogenic air pollutants in the neighborhood.

“You can’t have freedom and justice in this country if you can’t breathe your air, if you can’t open your window because of the toxic smells,” Senator Cory Booker, Democrat of New Jersey, said. “It may not be a billy club that is hitting you or a dog that is tearing your skin — those images from the Civil Rights movement — but it is violence to the body.”