The Latest: Expert says gray smoke at plant a better sign

HOUSTON (AP) -- The Latest on Harvey and its aftermath (all times local):

6:20 p.m.

A chemical safety expert says light gray smoke coming from the controlled burn of highly unstable compounds at a Houston-area chemical plant likely shows harmful elements are burning off.

Sam Mannan from Texas A&M University says the thick black smoke in previous, unplanned fires at the Arkema plant in Crosby, Texas, showed organic peroxides being stored in trailers weren't fully combusting. Fire officials and the company warned people not to inhale the smoke because it could make them sick.

Mannan says a proper burn-off leaves behind only carbon dioxide and water, creating a light gray smoke.

Arkema had said Harvey floodwaters engulfed the plant's backup generators, knocking out the refrigeration necessary to keep the peroxides from degrading and catching fire. In recent days three trailers had ignited, sending thick black smoke and tall flames into the air.

RELATED: 2 explosions rock flooded Houston-area chemical plant

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6 p.m.

Officials with a Houston-area chemical plant where fire authorities are conducting a controlled burn say trailers holding highly unstable compounds must burn to be neutralized.

Arkema spokesman Jeff Carr tells the Houston Chronicle the company must be confident the chemicals on the trailers are no longer active before it sends in safety officials and air quality observers.

Carr says there's a lot of work to be done, but that won't happen until after the burn.

Six of the trailers remained after three others ignited in recent days, sending thick black smoke and tall flames into the air in Crosby, Texas. The Harris County Fire Marshal's Office said Sunday it was taking "proactive measures" to ignite the remaining trailers.

A 1.5-mile evacuation zone around the plant remains in place.

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5:20 p.m.

A man living near a Houston-area chemical plant where a controlled burn is taking place told the Houston Chronicle he heard two booms and saw thick black smoke Sunday after authorities started a controlled burn.

The Harris County Fire Marshal's Office said in a statement Sunday afternoon that the decision was made to take "proactive measures" to ignite the remaining trailers at the Arkema plant in Crosby through controlled means. The office said that the measures don't pose any additional risk to the community. The 1.5-mile evacuation zone around the Crosby plant is still in place.

The man living nearby, John Rull, told the Chronicle that the explosions were louder than one he heard on Friday when two containers burned and that there was much more smoke. Rull lives two miles from the plant.

Six of the trailers had remained after three others ignited in recent days, sending thick black smoke and tall flames into the air.

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4:50 p.m.

Federal and state environmental officials say they're continuing to monitor smoke and air quality at a controlled burn at a Houston-area chemical plant.

The U.S. Environmental Protection Agency and the Texas Commission on Environmental Quality said Sunday afternoon that first responders were outside the evacuation zone for the Arkema plant in Crosby, but could respond quickly if needed.

Three trailers containing the compounds had already caught fire at the plant after backup generators were engulfed by Harvey's floodwaters, which knocked out the refrigeration necessary to keep the organic peroxides from degrading and catching fire.

The agencies say that they've been monitoring the air after the initial fires and have not found toxic concentration levels in areas away from the evacuated facility.

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4:10 p.m.

Authorities say they've started a controlled burn of the remaining trailers of highly unstable compounds at a Houston-area chemical plant that flooded because of Harvey.

The Harris County Fire Marshal's Office said in a statement Sunday afternoon that the decision was made to take "proactive measures" to ignite the remaining trailers at the Arkema plant in Crosby through controlled means. The office said that the measures don't pose any additional risk to the community. The 1.5-mile evacuation zone around the Crosby plant is still in place.

Six of the trailers had remained after three others ignited in recent days, sending thick black smoke and tall flames into the air.

Arkema had said Harvey's floodwaters engulfed its backup generators at the plant, knocking out the refrigeration necessary to keep the organic peroxides, used in such products as plastics and paints, from degrading and catching fire.

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2:40 p.m.

Floodwaters have receded in many areas hit hard by Harvey, but dozens of people are still cut off near the town of Liberty because of the swollen Trinity River.

Maggie King, who lives in city of about 8,400 people 45 miles northeast of Houston, was on hand with her two children to greet a Texas National Guard helicopter that landed at the town's fire department on Sunday with pallets of drinking water.

She says recovery from the storm is so far from over because there is so much to be repaired.

Fire Chief Brian Hurst says residents in outlying areas are nowhere close to being able to begin the recovery process since they can't even get into their homes. He says that for some, it will take months or even years.

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12:25 p.m.

Worshippers and relief workers are pausing from their chores across South Texas to seek God's favor as the area rebuilds.

Hurricane Harvey hit the region with high winds on Aug. 25 and then dumped more than four feet of rain in the Houston area days later. While the Gulf Coast suffers in miserable conditions from Corpus Christi, Texas, northward into Louisiana, the theme in many sermons Sunday was that God is greater.

The St. Joseph Catholic Church in Port Aransas hasn't had power since the storm but set out holy water and bug spray for parishioners before services Sunday morning. Many anointed themselves with both.

A less-formal group met and prayed outside a relief station on the beach town's main road.

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