Natalie Contreras and her three-year-old daughter Rosalina Chronister stand by a tribute to Contreras' deceased daughter Ciera Rose, who died aged four of cancer, at the Hartman Park Community Center in the Manchester neighborhood of Houston, Texas, U.S., December 15, 2018. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

The annual town Christmas parade, organized by the local Catholic church and sponsored by Valero, takes place in the Manchester neighborhood in industrial east Houston, Texas, U.S., December 15, 2018. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Natalie Contreras (2nd L) leaves a community event with her daughter Rosalina Chronister, grandmother Esperanza Contreras (R) and boyfriend Richard at the Hartman Park Community Center in the Manchester neighborhood of Houston, Texas, U.S., December 15, 2018. Contreras?s elder daughter Ciera Rose died, aged four, of cancer. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Cesareo takes a break while helping his cousin Fernando Alejandro move out of his home in the Manchester neighbourhood of Houston, Texas, U.S., October 3, 2018. Alejandro was bought out by Valero as the refinery plans to expand operations. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Dennys Nieto points to daughter Reyna Nieto, 14, while addressing representatives from the Valero refinery during a public hearing regarding a permit to legally release hydrogen cyanide at the Hartman Park Community Center in the Manchester neighborhood of Houston, Texas, U.S., September 20, 2018. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

The Fernando family moves out of their home in the Manchester neighbourhood of Houston, Texas, U.S., October 3, 2018. They were bought out by Valero as the refinery plans to expand operations. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES. TPX IMAGES OF THE DAY

Irma Garcia holds her eight-month-old grandson Efrain Rodriguez on the front porch of her home in the Manchester neighborhood of Houston, Texas, U.S., June 2, 2019. Garcia is a lifelong Manchester resident, she complains of persistent respiratory problems which she believes results from the neighborhood's air pollution. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Chemical plants and refineries near the Houston Ship Channel are seen next to the Manchester neighborhood in the industrial east end of Houston, Texas, U.S., August 9, 2018. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

A mariachi band plays for plant workers who just finished their shift at the LyondellBasell chemicals and refining plant in Pasadena, Texas, U.S., August 9, 2018. The plant workers have made it a tradition to bring in the mariachi band to this parking lot near their work, where they unwind with beers on payday. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

The Alejandro family moves out of their family home in the Manchester neighborhood of Houston, Texas, U.S., October 3, 2018. The house was bought by Valero as the refinery plans to expand operations. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Eugene Barragan washes his van in his yard in the Manchester neighborhood of Houston, Texas, U.S., June 2, 2019. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.

Environmental advocates from the Texas Environmental Justice Advocacy Series organization put up an anti-Valero sign before a public hearing regarding a Valero permit to legally release hydrogen cyanide at the Hartman Park Community Center in the Manchester neighborhood of Houston, Texas, U.S., September 20, 2018. REUTERS/Loren Elliott SEARCH "POLLUTION HOUSTON" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.