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A train derailment involving toxic chemicals in East Palestine, Ohio, has drawn national attention nearly a month later, putting pressure on the transport company and US President Joe Biden's administration to address the environmental effects.
The National takes a look at what has happened and what we know so far:
What happened?
Thirty-eight Norfolk Southern cars derailed on February 3 in a fiery, mangled mess on the Ohio-Pennsylvania border. No one was injured.
Officials moved thousands of people in the area to safety over fears of a potential explosion due to hazardous chemicals in five of the rail cars.
They later opted to release and burn toxic vinyl chloride from the tanker cars, sending flames and black smoke billowing into the sky again. Vinyl chloride is considered a carcinogen.
What caused the derailment?
The National Transport Safety Board did not reach conclusions about the cause of the accident but confirmed the discovery first reported last week of "what appeared to be a wheel bearing in the final stage of overheat failure".
Is it safe in the area?
Federal and state officials have repeatedly said it is safe for residents to return to the area, and that air testing in the town and inside hundreds of homes has not detected any concerning levels of contaminants.
The state says the local municipal drinking water system is safe, and bottled water is available for those with private wells.
How are the locals feeling?
Many of the 4,800 who live in East Palestine have expressed a sense of mistrust or have lingering questions about what they have been exposed to and how it will affect the future of their communities.
Some have complained of continuing chemical odours and nausea, rashes and other symptoms they believe are linked to the incident. Others have told of headaches and irritated eyes.
Large numbers of local workers are calling in sick as a result, and a local urgent care clinic is seeing more patients who have symptoms consistent with chemical exposure.
Some people are finding their cars and lawns covered in soot.
The hazardous chemicals that spilled from the train killed thousands of fish, and residents have talked about finding dying or sick pets and wildlife.
What is Norfolk Southern Corporation? And how are they responding?
Norfolk Southern is a one of the largest US rail transport companies, mainly operating in freight.
The company's chief executive, Alan Shaw, visited East Palestine and put out an open letter assuring that the company would “help make things right".
It started a fund for the community and has provided free bottled water to whoever wants it, but residents are angry. Mr Shaw publicly apologised again at a CNN town hall event.
The US has said the company must pay for the damage and clean-up work, and the EPA ordered company officials to attend town hall events after executives initially boycotted.
What is the Biden administration's response?
Many accused the White House of not responding as quickly, and US Transport Secretary Pete Buttigieg voiced regret.
"I felt strongly about this and could have expressed that sooner," Mr Buttigieg said on a trip to the crash site.
Mr Biden has defended his administration’s response, saying federal officials were there within hours of the derailment.
"We’re doing all we can,” he said. “The idea that we’re not engaged is just simply not there.”
Agencies including the Department of Transport, the Environmental Protection Agency, the Federal Emergency Management Agency and the Centres for Disease Control and Prevention have been active in Ohio.
What about the president?
Mr Biden has so far opted against visiting the crash site.
That decision has come under criticism from leading Republicans, with former president Donald Trump — who has announced his 2024 presidential campaign — visiting the town to distribute fast food and water.
“I’m keeping very close tabs on it," Mr Biden said.
How often do rail derailments happen in the US?
Railroads are the workhorse mode of transport for hazardous materials moving around the US, and in 2021 they carried about 900 million tonnes of such products, the American Chemistry Council says.
Under US law, rail carriers must transport chemicals even if the risk of doing so outweighs the reward.
Large railroads have fired more than 40,000 workers since 2016, leaving remaining employees overworked.
Although the number of US train derailments has dropped, there were still 1,093 last year.
While train derailments happen fairly regularly, those involving hazardous materials are less common.
In 2005, Norfolk Southern had a 16-car derailment in South Carolina, which included a tanker car with chlorine. That accident killed 10 people and took years to clean up.
Agencies contributed to this report